CORRIGENDUM No. 2 - Yap State Government

Supply of off-grid PV solar packages including modules, batteries, electronics, 

wirings, etc., including transport to Yap main island. 

 

Publication Reference#: 132631 

Project Title: YSPSC EFII01 SOGPVSP 

CORRIGENDUM No. 2 

1 Instructions to Tenderers (c4b_itt_en_instruction to tenderers_Yap132631EFII) 

1. In the document Instructions to Tenderers (c4b_itt_en_instruction to 

tenderers_Yap132631EFII), changes are made as follows: 

(a). Instead of: 

“Point 21.7 The performance guarantee referred to in the General Conditions is set at five percent 

(5%) of the amount of the contract and must be presented in the form specified in the annex to the 

tender dossier. It will be released within 45 days of the issue of the final acceptance certificate by the 

Contracting Authority, except for the proportion assigned to after-sales service.” 

Read: 

“Point 21.7 The performance guarantee referred to in the General Conditions is set at ten percent 

(10%) of the amount of the contract and must be presented in the form specified in the annex to the 

tender dossier. It will be released within 45 days of the issue of the final acceptance certificate by the 

Contracting Authority, except for the proportion assigned to after-sales service.” 

The updated tender dossier is available from the following Internet address: 

https://webgate.ec.europa.eu/europeaid/online-services/index.cfmdo=publi.welcome 

The tender dossier is also available from the Contracting Authority at the following internet addresses: 

https://sites.google.com/site/ef2yspsc/tender-dossier or http://www.yapstategov.org/bids.htm 

--- End of Document –

Supply of off-grid PV solar packages including modules, batteries, electronics, 

wirings, etc., including transport to Yap main island. 

 

Publication Reference#: 132631 

Project Title: YSPSC EFII01 SOGPVSP 

CLARIFICATIONS TO TENDERERS 

1 Tender Clarification Requests and Responses: 

I. Clarification Requests/Reponses 

II. (Attachment) PPA/SEAIPI Off Grid PV Power Systems Design Guidelines 

III. (Attachment) Letter of derogation # DEVCO/H3/BD/D (2011) 

1. Tender Clarification Requests and Responses: 

I. Clarification Requests/Reponses 

(a). Clarification Request #1: 

Annex III (Solar Batteries) 

As discussed with our production department on the Technical Sheet of 6V per battery requirement - 

"Each battery shall be a 6 volts DC (Vdc) in one robust container only, giving 6 V as nominal operating 

voltage; inter-cell connection shall not be exposed" - our battery is 2V per cells and provide inner-cell 

connector for battery bank but not produce as 6V in one robust container. Will such battery bank be 

acceptable 

Response: 

Yes, 6 volt or 2 volt cells will be accepted as long as the overall specifications are met. 

(b). Clarification Request #2: 

Annex III (Solar Batteries) 

We note that you required Flooded batteries, however will other types also be acceptable such as; GEL, 

ASTM, VRLA or other 

Response: 

No, only flooded batteries will be accepted. 

(c). Clarification Request #3: 

What is the exact delivery time– In the tender documents120 days as well as150 days are mentioned. 

Response: 

120 days, refer to Article 19 of the Special Conditions. 

(d). Clarification Request #4: 

Concerning the CD that shall accompany the offer – does it have to contain only the financial offer as a pdf 

or all documents of the offer

Response: 

The CD has to contain all submitted documents from the tenderer. 

(e). Clarification Request #5: 

It is nothing mentioned about the size of the containers to deliver the goods. Are there any requirements 

It is also not clear about the containers whether they are only used for delivering and going back to the 

tenderer or if you are going to keep them 

Response: 

Only 20’ containers can be accepted in Yap harbor. The containers can go back to the tenderer. 

(f). Clarification Request #6: 

PV Module Mounting Structure 

Can you please clarify if we also have to supply the post/poles for the array mounting structure 

Response: 

No, the modules will be ground-mounted on a concrete structure prepared by YSPSC. It is however 

important to include the technical drawings of the proposed mounting structure. 

(g). Clarification Request #7: 

Charge Controllers 

For a SCS the charge controller is specified to be 70A at 48V. Our question is can we offer a lesser amps 

controller than 70A if our array voltage will be configured at higher voltage to charge the 48V battery bank 

via MPPT technology. 

Response: 

You can offer an alternative design that we can look into however the official proposal needs to comply 

with the requested specs. Note that the specifications ask for a 48 V system and 3,360 Wp. It is however, 

possible to parallel 2 or 3 charge controllers, if this is recommended by the manufacturer. Please refer to 

point e.8 of Annex II. 

(h). Clarification Request #8: 

Wires, connectors and fuses 

Could please specify the cable run between the PV Module to Charge controller and the cable run 

between charge controller and battery for the SCS 

Response: 

The tender documents ask the tenderer under point g.2 to specify the wire sizes for the SCS with the note 

that “All wiring must be sized to keep line voltage losses to less than two percent (2%) in each sub-circuit 

and to allow the circuit to operate at a maximum of 60deg Celsius within the ampacity rating of the cable.” 

Voltage drop calculations need to be included in the proposal. 

(i). Clarification Request #9: 

Will 12V batteries be considered as well (e.g. 12V 190Ah for SHS) 

Response: 

No, the specs need to comply with the technical tender document. We have left a window open to send 

besides the offer that follows the set specification to propose and alternative design. For now only 6V and 

2V batteries will be accepted. 

(j). Clarification Request #10: 

Typically larger charge controllers (45A and above), function only as a charge controller or a load

controller, meaning that each unit does not have the capacity to control battery charge as well as load 

output. As the SCS system has an inverter, there is no need for the charge controller to also control the 

load. Thus requesting a charge controller “for a load of 70A (in 48V – 3360W)” isn’t really relevant. 

According to our design, a 60A charge controller is more than sufficient to manage the current from the 

PV array which is the primary concern when choosing such components. Please specify whether this will 

be acceptable. 

Response: 


besides the offer that follows the set specification to propose and alternative design. 

(k). Clarification Request #11: 

Will 24V nominal panels with 72 cells be considered Typically panels that are larger than 130W are 24V 

with 72 cells, and the requirements have allowed panels up to 185W. 

Response: 



(l). Clarification Request #12: 

For the SHS will 12V designs be considered If there are 12V DC loads to be used with the system, such as 

lights, then a system voltage of 12V would be beneficial and eliminate the need of a DC to DC converter 

within the system. It also opens up the range of inverters, as 24V 300W inverters are more difficult to find 

that 12V 300W inverters. 

Response: 



It is however possible that YSPSC might go for the 12V option therefore the charge controllers need to be 

able to work with 12V and with 24V. 

(m). Clarification Request #13: 

Regarding the panel warranty and the following excerpt from Annex II; 

The PV modules shall be warranted for at least 20 years and must not experience more than 15% of rated 

capacity reduction in output over their lifetime. They also shall be warranted for physical defect for a 

period of 10 years. 

Typically modules are supplied with 5 year physical defect warranty and 20 or 25 year warranty for a 

reduction in power output no greater than 20%. Please specify whether this standard warranty will be 

accepted If not please recommend a supplier offering a warranty for rated capacity reduction in output 

of only 15%. 

Response: 

The specifications are the basis of warranty guidelines that are to be met. However alternative warrantees 

shall be noted and will be considered but perhaps lead to a lower rating in the evaluation process if higher 

warrantees are offered by other tenderers. 

As per contract guidelines recommendations of specific suppliers meeting this warranty are not allowed. 

(n). Clarification Request #14: 

For the SHS both 10mm2 and 6mm2 cables have been specified, please state whether these are required 

to be double or single core cables 

Response: 

The SHS 10mm2 and 6mm2 cables are to be provided as per the specifications of “Annex II g.) wires, 

connectors and fuses” and “Annex III 1.8 Wires, connectors and fuses – Ref to g.)” and shall be standard 

and flexible insulated single core copper cables.

(o). Clarification Request #15: 

REFERENCE IS MADE TO TECHNICAL SPECIFICATIONS ITEM 1.2 AND ITEM 2.2 (MOUNTING RAILS): Please 

clarify how the mounting rails should be done. Have they to be deemed for ground mounting or roof 

mounting In case of ground mounting please clarify if a steel or aluminium pole must be supplied. 

Response: 

The tender dossier states that the panels will be ground mounted – see Annex II-specifications b.2 and b.3. 

No poles need to be provided as the footing (poles) will be made of concrete and completed by YSPSC. The 

tenderer will have to send, however, their technical drawing of the mounting structure they propose. – see 

Annex II-specifications b.3. 

(p). Clarification Request #16: 

REFERENCE IS MADE TO TECHNICAL SPECIFICATIONS: Please clarify if the inverters and charge controller 

must be mounted on an electrical control board. If so should the supplier deliver them pre-mounted on 

the electrical board or the end users will take care of mounting Moreover, in case of electrical board are 

to be supplied which kind of electrical board do you need Which would be the IP protection number 

Response: 

The design of the PV system is up to the tenderer and the most appropriate design will be selected. Please 

note that we follow the technical guidelines for the pacific islands for the design, find attached a copy of 

these guidelines. 

(q). Clarification Request #17: 

REFERENCE IS MADE TO TECHNICAL SPECIFICATIONS 

Should the bidder supply earth grounding with earth rod 

Response: 

Yes, see technical guide and the NEC electrical code for off-grid PV installations. 

(r). Clarification Request #18: 

REFERENCE IS MADE TO THE TENDER SCOPE: Does the contract include installation or only delivery CIF In 

case the contract includes installation please send us the list of installation sites. 

Response: 

No installation is required under this tender. 

(s). Clarification Request #19: 

REFERENCE IS MADE TO INVERTERS QUANTITY: Please confirm that inverter quantities is 400 and -in any 

case - a 10% extra inverter must be included as spare parts 

Response: 

The requested quantity is 400 Sinewave inverters 24Vdc 120 Vac 60Hz 300W plus 10% spares and 20 Sine 

wave inverter 48Vdc 120Vac 60Hz 3000W plus 10% spares 

(t). Clarification Request #20: 

Rules of Origin: Clause 3 of Instructions to Tenderers. 

Please provide list of countries applicable for this project. Could you provide us with the copy of the 

Reference note of derogation # DEVCO/H3/BD/D (2011) 

Response: 

See the attached copy of the “Letter of Derogation”:

(u). Clarification Request #21: 

Photovoltaic Modules – a.4); 

PV modules must be framed with marine graded aluminum. I believe this refers to Anodized Aluminum 

frame 

Response: 

Anodized Aluminum will also be accepted 

(v). Clarification Request #22: 


NEC requires PV Power Source to have Disconnect Switches, is this required for this project 

Response: 

Yes – All NEC guidelines must be followed 

(w). Clarification Request #23: 


Confirm that PV Structure will be grounded using grounding bolts, lugs & screws 

Response: 

Correct 

(x). Clarification Request #24: 


Please confirm if these structures will be mounted on a concrete pad embedded in ground 

Response: 

The systems will be installed on concrete poles. The poles will be prepared by YSPSC but the tenderer must 

provide the technical drawings of the mounting requirements for the system that they are proposing 

(y). Clarification Request #25: 

Solar Batteries; 

Will batteries with higher number of cycles be given preference over the price 

Response: 

Yes – All components must meet and/or exceed tender dossier specification 

(z). Clarification Request #26: 


Will batteries that have never been used in Pacific Island be considered if they meet the specifications are 

better priced over the battery that has proven track record in Pacific Island but may be higher in price 

Response: 

Yes – All components must meet and/or exceed tender dossier specification 

(aa). Clarification Request #27: 


Will batteries be given preference with 5 years Guarantee instead of warranty 

Response: 

Refer to the tender specifications for batteries that shall be follow and require a “warranty”

(bb). Clarification Request #28: 


NEC requires each equipment to have disconnect switch, is this required for this project 

Response: 

All NEC guidelines must be followed. All main components shall be able to be disconnected by a breaker 

and/or disconnect switch 

(cc). Clarification Request #29: 


Any preference on Battery Casing – transparent, clear etc 

Response: 

No preference is given to the color of the battery casing, but note that the acid level must be visible from 

outside. 

(dd). Clarification Request #30: 

Battery Enclosures; 

Will the Batteries be installed indoors or outdoors 

Response: 

Outdoors 

(ee). Clarification Request #31: 


Any specific requirement for Battery Enclosure Material 

Response: 

The battery enclosure must have a long lifetime and must be suitable for outdoor marine environment 

usage. 

(ff). Clarification Request #32: 


Do you intend to attach the Enclosure to the wall or floor or it will be just sitting on the ground etc 

Response: 

On the ground 

(gg). Clarification Request #33: 

Charge Controllers (SHS & SCS); 

Will MPPT Charge Controllers be considered for this project, MPPT Charge controllers are more efficient 

but there is cost difference as well 

Response: 

Yes 

(hh). Clarification Request #34: 

Charge Controllers (SHS & SCS); 

Is Battery Temperature Sensor required for temperature compensation charging, this will be of great help 

due to temperature variance 

Response: 

Refer to the requirements in the technical specifications for charge controllers. For the SCS a battery sensor 

would be required

(ii). Clarification Request #35: 

Since the panels will be installed outside and the controller inside, do we have to provide disconnect 

switches at the Array and also before the Charge Controller Entry. This means 2 disconnection points 

between the PV Array and Charge Controller. Please confirm. 

Response: 

Refer to the tender specifications for your systems designs for installation. These systems are to be 

packaged component stand-alone outside compact systems which are to be installed as complete units 

externally from the location being served by each system. All NEC guidelines must be followed as needed 

for design. Follow the instructions and you can include changes and/or additions in your design for 

evaluation. 

(jj). Clarification Request #36: 

As per the NEC guidelines, we can isolate one conductor and ground the other conductor or isolate both 

current carrying conductors by using appropriate circuit breakers. Please confirm if we can to supply these 

isolators / disconnection devices with this tender 

Response: 

All NEC and SEIAPI technical guidelines must be followed for design of stand-alone system. The guidelines 

are available online and have been attached with this email. The tenderer must design the system 

following these guidelines. 

(kk). Clarification Request #37: 

We have a question regarding the mounting structures for the modules. 

Will they be rammed into the ground or will there be a concrete foundation 

Response: 

The systems will be installed on concrete poles. The poles will be prepared by YSPSC but the tenderer 

proposal must provide the technical drawings for the poles along with the mounting requirements for the 

system/s that they are proposing. 

(ll). Clarification Request #38: 

Since SCS will be installed outside (compact installation) 

please confirm if both the controllers, inverters and all other accessories to be installed outside 

Response: 

SCS to be outside and please refer to the complete tender dossier and especially the documents of 

“Instruction for Tenderers” long with “Annex II” for definition of “PV solar packages” and “complete” 

system for both the SCS/SHS. All system components to be included with such. 

(mm). Clarification Request #39: 

Is SHS also a compact system with controllers and inverters mounted outdoors 

Response: 

Correct and again please refer to tender document Annex II item “h).” which provides guide to the region 

and conditions of the where these systems will be installed. Reference to “Yap, Federated States of 

Micronesia” is made and which also encompasses the outer islands of the state of Yap, FSM. Research and 

becoming familiar with this region and the conditions that can be encountered is strongly encouraged. 

(nn). Clarification Request #40: 

Confirmation on Tender Guarantee 

If TG is submitted in another form, say Bank Guarantee or Bank Draft, will the company be disqualified 

from the tendering process

Response: 

The tender dossier requires that EU “Tender Guarantee Form” format must be used and submitted with the 

tender proposal 

(oo). Clarification Request #41: 

“Continuous Power at 25°C minimum 300W – maximum 400W” 

We can offer an Inverter with this value expressed in [VA] instead of [W]. Due to the missing data on 

number and type of devices that will be loaded by the grid-off plants, we cannot give the value for 

Continuous power expressed in [W]. Would you please be so kind to tell us if the range of Continuous 

power of 650-800 [VA] will be good as well. 

Exactly the same thing we would like to know regarding the technical specification for SCS plants as 

follows: 

“Continuous Power at 25°C minimum 3000W – max.3500W” 

Our proposal for the Continuous power is 5000 [VA] .Could it be suitable for SCS needs 

Response: 

It is acceptable to express the inverter values in “VA” as well as “W”. The ratings shall be within the 

guideline ranges as noted in the specifications of Annex II f.1) and f.2). Each tenderer must conclude to the 

best of their knowledge the best practiced design and component/materials provision meeting the 

specified guidelines. The overall design and technical specifications will be given preference and systems 

with established histories of performance shall be preferred. 

(pp). Clarification Request #42: 

Equipment delivery must be carried out in kits, in a grouped format, or it can be delivered each of their 

components separately: panels, regulators, inverters, batteries and accessories.” 

Response: 

Reference to “Equipment Delivery in kits” is not found & therefore refer to Annex II document (Annex II - 

Specificationsv2_final) related to this components delivery question as to be “supplies are to be made in 

one lot and to be delivered….” 

(qq). Clarification Request #43: 

At point a.3) of technical specifications standard IEEE 1262 is required 

IEEE 1262 served its purpose as the first consensus qualification test standard for thin film modules but, in 

this tender, are silicon types. Therefore, the standard IEEE 1262 is not applicable. 

Response: 

This is a United States informational standard basis for PV panels that tenderers shall refer to for 

establishing their proposal submissions and is for reference purposes. Any subsequent standard/s for PV 

module qualification guidelines that have replaced and/or succeeded prior recommended practices shall be 

the responsibility of the tenderer and shall be followed.

II. 

(Attachment) PPA/SEAIPI Off Grid PV Power Systems Design Guidelines 

PPA/SEAIPI Off Grid PV 

Power Systems Design 

Guidelines

OFF GRID PV POWER SYSTEMS 

SYSTEM DESIGN GUIDELINES 

These guidelines have been developed by the Sustainable Energy Industry Association of the Pacific Islands in 

Collaboration with the Pacific Power Association 

They represent latest industry BEST PRACTICE for the design and installation of PV Grid Connect Systems. 

© Copyright 2012 

While all care has been taken to ensure this guideline is free from omission and error, no responsibility can be taken 

for the use of this information in the design of any PV grid connect system. 

Issue 1 September 2012

GENERAL 

The design of any off-grid system should consider, other than the electrical load, a number of criteria such as: 

o Budget 

o Acceptable genset runtime 

o Power quality 

o Noise levels 

o Environmental impact 

o Site accessibility 

o Aesthetics 

o Level of automation 

Note: This guidelines are based on d.c. bus systems and do not include the new a.c. bus hybrid systems currently available. Guidelines dedicated to 

hybrid Systems will be developed. 

ENERGY SOURCE MATCHING 

Heating and lighting should be supplied from the most appropriate source. For example - 

o cooking - gas or wood burning stove 

o water heating - solar water heating with gas or wood backup 

o Lighting - electrical lighting most often used but natural light ( daylighting ) should be considered. 

ENERGY EFFICIENCY 

All appliances should be chosen for the lowest possible energy consumption for each desired outcome, such 

as 

o High efficiency lighting 

o Energy efficient refrigeration 

STANDARDS for DESIGN 

System designs should follow any standards that are typically applied in the country or region where the solar 

installation will occur. The following lists the relevant standards in Australia, New Zealand and USA They are 

listed because some Pacific island countries and territories do follow those standards. These standards are 

often updated and amended so the latest version should always be applied. 

In Australia and New Zealand the main standards required include: 

o AS/NZS3000 Wiring Rules 

o AS/NZS4509 Stand-alone power systems 

o AS 4086.2 Secondary batteries for stand-alone power supplies 

o AS/NZS5033 PV Array 

o AS 3010.1 Electrical Installations - Supply Generating set 

o AS 1768 Lightning Protection 

o AS 3595 Energy management programs 

o AS 1359.51 Noise level limits 

In USA PV systems must be in accordance with the following codes and standards: 

o Electrical Codes-National Electrical Code Article 690:Solar Photovoltaic Systems and NFPA 70 

Uniform Solar Energy Code 

o Building Codes- ICC, ASCE 7 

o 

o 

UL Standard 1701: Flat Plat Photovoltaic Modules and Panels 

UL Standard 1741: Standard for Inverter, converters, Controllers and Interconnection System 

Equipment for use with Distributed Energy Resources 

Issue 1 September 2012 Page 1

INTRODUCTION 

Four major issues arise when designing a system: 

1. the load (power) required to be supplied by the system is not constant over the period of one day; 

2. the daily energy usage varies over the year; 

3. the energy available from the PV array may vary from time to time during the day; 

4. the energy available from the PV array will vary from day to day during the year. 

Since the system is based on photovoltaic modules, then a comparison should be undertaken between the 

available energy from the sun and the actual energy demands The worst month is when the ratio between 

solar energy available and energy demand is smallest. 

The design of an off-grid power requires a number of steps. A basic design method follows: 

1. Determination of the energy usage that the system must supply. 

2. Determination of the battery storage required. 

3. Determination of the energy input required from the PV array or other sources (eg battery 

charger/generator) 

4. Selection of the remainder of system components. 

LOAD (ENERGY) ASSESSMENT 

Electrical power is supplied from the batteries (DC) or via an inverter to produce either 230 volts AC (South 

Pacific) or 110 / 120 volts AC (North Pacific). Electrical energy usage is normally expressed in watt hours (Wh) 

or kilowatt hours ( kWh ). 

To determine the daily energy usage for an appliance, multiply the power of the appliance by the number of 

hours per day it will operate. The result is the energy (Wh) consumed by that appliance per day. 

Appliances can either be DC or AC. An energy assessment should be undertaken for each type, examples of 

these are shown in tables 1 and 2. 

You need to calculate the electrical energy usage with the customer. Many systems have failed over the years 

not because the equipment has failed or the system was installed incorrectly, BUT BECAUSE THE 

CUSTOMER BELIEVED THEY COULD GET MORE ENERGY FROM THEIR SYSTEM THAN THE SYSTEM 

COULD DELIVER. It failed because the customer was unaware of the power/energy limitations of the 

system. 

The problem is that the customer may not want to spend the time determining their realistic power and energy 

needs which is required to successfully complete a load assessment form. They just want to know: How much 

for a system to power my lights and TV 

A system designer can only design a system to meet the power and energy needs of the customer. The 

system designer must therefore use this process to understand the needs of the customer and at the same 

time educate the customer. Completing a load assessment form correctly (Refer to table 1 and 2 below) does 

take time; you may need to spend 1 to 2 hours or more with the potential customer completing the tables. It is 

during this process that you will discuss all the potential sources of energy that can meet their energy needs 

and you can educate the customer on energy efficiency. 


Worked Example 

Table 1 DC Load (energy) Assessment 

(1) (2) (3) (4a) (5a) (4b) (5b) (6) Comments 

dry season wet season Contribution 

Power 

to maximum 

Appliance Number 

Usage Energy Usage Energy demand 

Time 

Time 

W h Wh h Wh W 

Light 4 7 4 112 4 112 28 

Daily Load energy-d.c loads (Wh) ( DC 7a) 112 (DC 7b) 112 

Maximum d.c. demand (W) (DC 8) 28 

Table 2 AC Load (energy) Assessment 

(1) (2) (3) (4a) (5a) (4b) (5b) (6) (7) (8) (9a) (9b) 

dry season wet season 

Contribution 

Contribution to 

Power 

to max 

surge demand 

Appliance No. 

Power demand Surge Potential Design 

Usage 

Time 

Energy Usage 

Time 

Energy Factor 

Factor 

Comments 

W h Wh h Wh VA VA VA 

TV 100 3 300 3 300 0.8 125 4 500 125 

Refrigerator 100 12 1200 12 1200 0.8 125 4 500 500 Duty cycle of 

0.5 included 

Daily Load Energy A.C 

1500 

1500 

Loads (Wh) (AC10a) 

(AC10b) 

maximum demand (VA) (AC11) 250 1000 

Surge demand (VA) (AC12) 625 


In the worked example on the previous page, the TV and refrigerator are using AC electricity so we have to 

take into account the efficiency of the inverter. Typically the peak efficiency of the inverter may be over 90% 

but in many systems the inverter will sometimes be running when there is very little load on the inverter, so the 

average efficiency is about 85% to 90%. Then we must divide the total AC energy used by this figure to obtain 

the energy required to be supplied to the inverter from the battery bank. 

For the worked example assume the efficiency of the chosen inverter is 90%. 

Daily battery load (energy) from AC loads = 1500Wh ÷ 0.9 = 1667 Wh 

Daily battery load (energy) from DC loads = 112 Wh 

To get the total load(energy) as seen by the battery, you add the two figures together: 

1667 + 112= 1779Wh 

If there are no AC loads, then you only have to work out the load from the DC appliances, and not include the 

inverter (or the inverter efficiency). 

BATTERY SELECTION 

DETERMINATION OF SYSTEM VOLTAGE 

System voltages are generally 12, 24 or 48 Volts. The actual voltage is determined by the requirements of the 

system. For example, if the batteries and the inverter are a long way from the energy source then a higher 

voltage may be required to minimise power loss in the cables. In larger systems 120V or 240V DC could be 

used, but these are not typical household systems. 

As a general rule, the recommended system voltage increases as the total load increases. For small daily 

loads, a 12V system voltage can be used. For intermediate daily loads, 24V is used and for larger loads 48V is 

used. 

1 kWh 3-4 kWh 

Use 12 Volt 

system voltage 

Use 24 Volt 


Use 48 Volt 


The changes over points are roughly at daily loads of 1 kWh and 3-4 kWh but this will also be dependent on 

the actual power profile. 

One of the general limitations is that maximum continuous current being drawn from the battery should not be 

greater than 150A. 

BATTERY SIZING 

To convert Watt-hours (Wh) to Amp-hours (Ah) you need to divide by the battery system voltage. 

For the worked example the daily energy usage was 1779Wh , so we select a battery system voltage of 24 

Volts. 

This means that the daily Ah demand on the batteries will be: 


Ah = Wh ÷ system voltage 1779Wh ÷ 24 = 74 Ah 

So at the moment the minimum size battery to meet the daily energy requirements in the example is: 74Ah 

Battery capacity is determined by whichever is the greater of the following two requirements: 

1. The ability of the battery to meet the energy demand of the system, often for a few days, sometimes 

specified as ‘days of autonomy’ of the system; 

OR 

2. The ability of the battery to supply peak power demand. 

The critical design parameters include: 

Parameters relating to the energy requirements of the battery: 

a) Daily energy demand 

b) Daily and maximum depth of discharge 

c) Number of days of autonomy 

Parameters relating to the discharge power (current) of the battery: 

a) Maximum power demand 

b) Surge demand 

Parameters relating to the charging of the battery: 

a) Maximum Charging Current 

Based on the these parameters there are a number of factors that will increase the battery capacity in order to 

provide satisfactory performance. These correction factors must be considered. 

1. Days of Autonomy 

Extra capacity is necessary where the loads require power during periods of reduced input. The battery 

bank is often sized to provide for a number of days autonomy. A common period selected is 5 days. 

Where a generator is operating on a regular basis the autonomous period can be reduced. 

In other cases, where there is no auxiliary charging source, the period of autonomy is often increased to 7 

days or more. 

For the worked example assume 5 days autonomy . 

ADJUSTED 

Battery Capacity = 74 x 5 = 370 Ah 

2. Maximum Depth of Discharge 

Battery manufacturers recommend a maximum depth of discharge (DOD). If this is regularly exceeded the 

life of the battery is severely reduced. This could be 50% or for some solar batteries as high as 80%. 

For the worked example Assume a maximum DOD of 70%. 

ADJUSTED 

Battery Capacity = 370 ÷ 0.7 = 529 Ah 

3. Battery Discharge Rate 

The actual discharge rate selected is highly dependent on the power usage rates of connected loads. Many 

appliances operate for short periods only, drawing power for minutes rather than hours. This affects the battery 


selected, as battery capacity varies with discharge rate. Information such as a power usage profile over the 

course of an average day is required for an estimate of the appropriate discharge rate. 

For small systems this is often impractical. 

Where the average rates of power usage are low, the battery capacity for 5 days autonomy is often selected at 

the 100hr rate of discharge for the battery. 

For the worked example 

ADJUSTED 

Battery Capacity = 529 Ah (@ C 100 ) 

Where average power usage rates are high, it may be necessary to select the battery capacity for 5 days 

autonomy at a higher discharge rate. eg. the 10 (C 10 ) or 20hr (C 20 ) rate 

4. Battery Temperature derating 

Battery capacity is affected by temperature. As the temperature goes down, the battery capacity reduces. The 

following graph gives a battery correction factor for low temperature operation. Note that the temperature 

correction factor is 1 at 25°C as this is the tempe rature at which battery capacity is specified. 

In the tropics it is often still 20°C+ in the even ings so unless the system is located in a mountainous region 

that does get cold then ignore the temperature derating. If you want to be conservative add 5% to the capacity 

to allow for this factor. 

BATTERY SELECTION 

Deep discharge type batteries / cells should be selected for the required system voltage and capacity in a 

single series string of battery cells. 

Parallel strings of batteries are not recommended. 

Where this is necessary each string must be separately fused. 

For the worked example a battery of at least 529 Ah (@C 100 ) should be used. 

PV ARRAY SIZING- Standard Switched Controllers 

The calculation for determining the size of the PV array is dependent on the type of controller used. Historically 

standard switched controllers were the most common controllers used. In recent years a number of maximum 


power point trackers (MPPT) have become available. This section determines how to size the PV array based 

on switched controllers based on the PV array meeting the daily load requirements all year. Later in the guide 

is a section on how to size a PV array using a MPPT. 

The size of the PV array should be selected to take account of: 

seasonal variation of solar irradiation 

seasonal variation of the daily energy usage 

battery efficiency 

manufacturing tolerance of modules 

dirt 

temperature of array (the effective cell temperature) 

Solar irradiation data is available from various sources. Some countries have data available from their 

respective meteorological department. One source for solar irradiation data is the NASA website: 

http:/eosweb.larc.nasa.gov/sse/. RETSCREEN, a program available from Canada, incorporates the NASA 

data and it is easier to use. Please note that the NASA data has, in some instances, had higher irradiation 

figures than that recorded by ground collection data in some countries. but if there is no other data available it 

is data that can be used. 

Solar irradiation is typically provided as kWh/m 2 however it can be stated as daily peak Sun Hours (PSH). This 

is the equivalent number of hours of solar irradiance of 1kW/m 2 . 

Attachment 1 provides data on the following sites: 

• Suva, Fiji (Latitude 18°08 ′S Longitude 178°25 ′E) 

• Apia, Samoa (Latitude 13 o 50' S' Longitude 171 o 44' W) 

• Port Vila, Vanuatu (Latitude 17° 44' S Longitude 168° 19' E) 

• Tarawa, Kiribati (Latitude 1°28'N, Longitude 173°2 'E) 

• Raratonga, Cook islands( Latitude 21°30'S, Longitude 160°0'W) 

• Nuku’alofa, Tonga (Latitude 21º14'S Longitude 175º22'W) 

• Honiara, Solomon Islands (Latitude 09°27'S, Lon gitude 159°57'E) 

• Koror ,Palau ( Latitude 7°20’N Longitude 134°28'E) 

• Ponapei, Pohnpei FSM (Latitude: 6°54'N, Longitude : 158°13'E) 

• Majuro, Marshall Islands (Latitude: 7º 12N, Longitude 171º 06E) 

• Alofi, Niue (Latitude 19°04' S. Longitude 169° 55' W) 

• Nauru (Latitude 0º55’S, Longitude 166º 91’E) 

• Tuvalu (Latitude 8°31 ′S, Longitude 179°13 ′E) 

• Hagåtña, Guam (Latitude 13°28 ′N Longitude: 144°45 ′E) 

• Noumea, New Caledonia (Latitude 22°16 ′S Longitude: 166°27 ′E) 

• Pago Pago, American Samoa (Latitude 14°16 ′ S Longitude: 170°42 ′W) 

The variation of both the solar irradiation and the load energy requirement should be considered. If there is no 

variation in daily load between the various times of the year then the system should be designed on the month 

with the lowest irradiation that is peak sun hours (PSH). 

DAILY ENERGY REQUIREMENT FROM THE PV ARRAY 

In order to determine the energy required from the PV array, it is necessary to increase the energy from the 

battery bank to account for battery efficiency. 

. 

The average columbic efficiency (in terms of Ah) of a new battery is 90% (variations in battery voltage are not 

considered). 

For the worked example the daily energy requirement expressed in Ah from the battery is 74 Ah. Allowing for 

the battery efficiency, the solar array then needs to produce… 

74 Ah ÷ 0.9 = 82.2 Ah 

Assume the worst months PSH is 5. 


Therefore the required PV array output current is: 

82.2 Ah ÷ 5 PSH = 16.5 A 

OVERSIZE FACTOR 

If the system does not include a fuel generator which can provide extra charging to the battery bank then the 

solar array should be oversized to provide the equalisation charging of the battery bank. In Australia and New 

Zealand this is between 30% and 100%. It is recommended in the Pacific that this is 10%. 

For the worked example the adjusted array output current is: 

16.5A x 1.1 = 18.1 A 

DERATING MODULE PERFORMANCE 

The PV array will be de-rated due to: 

• Manufacturer’s Tolerance: Most manufacturers rate their modules ± a percentage (eg ±3%) or wattage 

(eg ±2W). Unless every module is tested and its actual rating is known then the modules should be derated 

by the manufacturer’s tolerance. 

• Dirt: Over a period of time dirt or salt (if located near the coast) can build up on the array and reduce 

the output. The output of the module should therefore be derated to reflect this soiling. The actual value 

will be dependent on the site but this can vary from 0.9 to 1 (i.e. up to 10% loss due to dirt). 

• Temperature: Modules’ output power decreases with temperature above 25°C and increases with 

temperatures below 25°C. The average cell temperatu re will be higher than the ambient because of the 

glass on the front of the module and the fact that the module absorbs some heat from the sun. The 

output power and/or current of the module must be based on the effective temperature of the cell. This 

is determined by the following formula: 

T cell-eff = T a.day + 25°C 

Where 

T cell-eff = the average daily effective cell temperature in degrees Celsius (°C) 

T a.day = the daytime average ambient temperature for the month that the sizing is being undertaken. 

Since the modules are used for battery charging, the current at 14 Volts (a good battery charging voltage) at 

the effective cell temperature should be used in calculations. If curves are unavailable to determine the current 

at effective cell temperature then use the Normal Operating Cell temperature (NOCT) provided by the 

manufacturers. 

Therefore the derated module output current is calculated as follows: 

The Current of the module at 14V and effective cell temperature (or NOCT current) 

multiplied by derating due to manufacturers tolerance 

multiplied by derating due to dirt 

I (NOCT) x f man x f dirt 

If a module has a 3% (0.03) manufacturers tolerance, then the module current is derated by multiplying by 

0.97 (1-0.03). 

If a module has a 5% (0.05) loss due to dirt then the module current is derated by multiplying by 0.95 (1-0.05). 

For the worked example the selected module has a peak rating of 80W P . 

An 80 watt solar module (still used in many small off-grid systems) typically has the following data: 


Table 3: 80 W module data 

Rated Power 

80W 

Power Tolerance ± 5% 

Nominal Voltage 

12V 

Maximum Power Voltage, V mp 17.6V 

Maximum Power Current, I mp 4.55A 

Open Circuit Voltage, V oc 22.1V 

Short Circuit Current, I sc 4.8A 

NOCT 

47±2°C 

Current at 14V and NOCT 4.75A 

Assuming a 5% dirt derating then the adjusted output current of the above module is: 

ADJUSTED 

Module current = I (NOCT) x 0.95 ( ← minus 5% for manufactures tol) x 0.95 ( ← minus 5% for dirt) 

= 4.75A x 0.95 x 0.95 = 4.29A 

NUMBER OF MODULES REQUIRED IN ARRAY 

First determine number of modules in series, To do this divide the system voltage by the nominal operating 

voltage of each module. In our example: 

For the worked example Number of modules in series = 24V ÷ 12V = 2 

Therefore the array must comprise of series connected strings of 2 modules. 

To determine the number of strings in parallel, the PV array output current required (in A) is divided by the 

output of each module (in A). 

For the worked example Number of strings in parallel =18.1A ÷ 4.29A = 4.22 

Do we round up or down If you want to be conservative you would round up. However in this example we 

suggest you round down since this calculation was based on the worst month and we allowed an oversize of 

10%.This does need to be determined for each system. 

For the worked example The number of modules in the array = 4 x 2 = 8 

The peak rating of the array is : 8 x 80W P = 640W P 

INVERTER SELECTION 

The type of inverter selected for the installation depends on factors such as cost, surge requirements, power 

quality and for inverter/chargers, a reduction of the number of system components necessary. Inverters are 

available in 3 basic output types - Square wave, modified square wave and sine wave. 

There are few square wave inverters used today. 

Modified square wave inverters generally have good surge and continuous capability and are usually cheaper 

than sine wave types. However, some appliances, such as audio equipment, television and fans can suffer 

because of the output wave shape. 

Sine wave inverters often provide a better quality power than the 230V (or 110V or 120V) grid supply. 


INVERTER SIZING 

The selected inverter should be capable of supplying continuous power to all AC loads 

AND 

providing sufficient surge capability to start any loads that may surge when turned on and particularly if they 

turn on at the same time. 

Where an inverter cannot meet the above requirements attention needs to be given to load control and 

prioritisation strategies. 


From the load (energy) assessment on page 3, a selected inverter must be capable of supplying 250VA 

continuous with a surge capability of 625VA. 

CONTROLLERS- Standard Switched Controller 

PV controllers on the market range from simple switched units that only prevent the overcharge (and 

discharge) of connected batteries to microprocessor based units that incorporate many additional features 

such as … 

o 

o 

o 

o 

o 

PWM and equalisation charge modes 

DC Load control 

Voltage and current metering 

Amp-hour logging 

Generator start/stop control 

Unless the controller is a model that is currently limited these should be sized so that they are capable of 

carrying 125% of the array short circuit current and withstanding the open circuit voltage of the array. If there is 

a possibility that the array could be increased in the future then the controller should be oversized to cater for 

the future growth. 

(Note: sometimes the controller is called a regulator) 


The controller chosen must have a current rating 

> 1.25 x 4 x 4.8 A = 24A at a system voltage of 24V. 

GENERATORS & BATTERY CHARGING 

To reduce system costs, it is common for some form of auxiliary charging to be used to provide energy when 

daily energy requirements are greater than the daily PV input into the system. This is usually a 

diesel/petrol/gas powered generator. Where the electrical output is 230V AC (or 110V or 120V) a battery 

charger is required. 

An inverter/charger can be used; otherwise a separate charger unit is needed. 

Factors that must be considered when using internal combustion generators are 

o Fuel storage and spillage precautions 

o Noise emission control 

o Ventilation 

o Generator loading 

With regards to generator loading, a generator should supply greater than 50% of its maximum rating while 

running. Loading of less than 50% increases running and maintenance costs and reduces generator life. 


( refer to genset manufacturers' information ) 

BATTERY CHARGER SIZING 

A charger must be capable of supplying voltage greater than the nominal system voltage. 

The maximum charging current must not be greater than that recommended by the battery manufacturer but a 

usable estimate is a maximum charge current of around 10% of the C 10 rate. 

PV ARRAY SIZING- MPPT 

DAILY ENERGY REQUIREMENT FROM THE PV ARRAY 

The size of the PV array should be selected to take account of: 

seasonal variation of solar irradiation 

seasonal variation of the daily energy usage 

battery efficiency (wh) 

Cable losses 

MPPT efficiency 

manufacturing tolerance of modules 

dirt 

temperature of array (the effective cell temperature) 

With the standard controller the only sub-system losses was the battery efficiency and the calculations are 

undertaken using Ah. When using a MPPT the calculations are in Wh and the sub-system losses in the system 

include: 

• Battery efficiency (watthr) 

• Cable losses 

• MPPT efficiency 

In order to determine the energy required from the PV array, it is necessary to increase the energy from the 

battery bank to account for all the sub-system losses. 

For the worked example assume cable losses is 3% (transmission efficiency of 97%), MPPT efficiency of 95% 

and battery efficiency of 80% 

Subsystem efficiency = 0.97 x 0.95 x 0.8 = 0.737 

Energy required from the PV array = 1779Wh ÷ 0.737 = 2413Wh 

Assume the worst months PSH is 5. 

Therefore the required peak PV array output power is: 

2413Wh ÷ 5 PSH = 482W P 

OVERSIZE FACTOR 

If the system does not include a fuel generator which can provide extra charging to the battery bank then the 

solar array should be oversized to provide the equalisation charging of the battery bank. In Australia and New 

Zealand this is between 30% and 100%. It is recommended in the Pacific that this is 10%. 

For the worked example Therefore the adjusted array output current is: 

482W P x 1.1 = 530W P 

DERATING MODULE PERFORMANCE 

The PV array will be de-rated due to: 


• Manufacturer’s Tolerance: Most manufacturers rate their modules ± a percentage (eg ±5%) or wattage 

(eg ±2W). Unless every module is tested and its actual rating is known then the modules should be derated 

by the manufacturer’s tolerance. 

• Dirt: Over a period of time dirt or salt (if located near the coast) can build up on the array and reduce 

the output. The output of the module should therefore be derated to reflect this soiling. The actual value 

will be dependent on the site but this can vary from 0.9 to 1 (i.e. up to 10% loss due to dirt). 

• Temperature: Modules’ output power decreases with temperature above 25°C and increases with 

temperatures below 25°C. The average cell temperatu re will be higher than the ambient temperature 

because of the glass on the front of the module and the fact that the module absorbs some heat from 

the sun. The output power and/or current of the module must be based on the effective temperature of 

the cell. This is determined by the following formula: 

T cell-eff = T a.day + 25°C 

Where 

T cell-eff = the average daily effective cell temperature in degrees Celsius (°C) 

T a.day = the daytime average ambient temperature for the month that the sizing is being undertaken. 

With switched controllers the temperature effect was used to determine the operating current of the 

module/array. With MPPT’s the derating power factor must be calculated. 

The three main types solar modules available on the market each have different temperature coefficients. 

These are: 

• Monocrystalline: Modules typically have a temperature coefficient of –0.45%/ o C. That is for every 

degree above 25 o C the output power is derated by 0.45%. 

• Polycrystalline: Modules typically have a temperature coefficient of –0.5%/ o C. 

• Thin Film: Modules have a different temperature characteristic resulting in a lower co-efficient typically 

around 0%/°C to -0.25%/°C, but remember to check with the manufacturer 

The typical ambient daytime temperature in many parts of the Pacific is between 30 and 35 o C during some 

times of the year. So it would not be uncommon to have module cell temperatures of 55 o C or higher. 

For the worked example Assume the ambient temperature is 30 o C.. 

Therefore the effective cell temperature is 

30 o C +25 o C = 55 o C 

Therefore this is 30 o C above the STC temperature of 25 o C. 

The 80 W P module used in this example is a polycrystalline module with a derating of -0.5%/ o C 

Therefore the losses due to temperature would be: 

Temperature loss = 30 o C x 0.5%/ o C = 15% loss 

This is a temperature derating factor of 0.85 

Assuming a 5% dirt derating then the adjusted output power of the 80W module is: 

Adjusted module power = 80 x 0.95 x 0.95 x 0.85 = 61.4W 

NUMBER OF MODULES REQUIRED IN ARRAY 

To calculate the required number of modules in the array, divide the required array power by the adjusted 

module power. 



Number of modules in array =530 ÷ 61.4 = 8.63 

(Note for the switch regulator we had 4.29 parallel strings of 2 modules in series) 

The actual number of modules will be dependent on the MPPT selected. If it was 9 then the rating of the array 

is : 9 x 80W P = 720W P 

SELECTING MPPT 

The following table gives some examples of MPPT’s currently available on the market: 

Model d.c. battery 

Voltage (V) 

STECA 

Solarix 

MMP2010 

Phocos 

MMPT 

100/20-1 

Morningstar 

SS-MPPT-15L 

Outback Flex 

Max 80 

Outback Flex 

Max60 

Table 4: MPPT Data 

Input voltage Max d.c. Max(W) Solar 

range (V) Battery Array 

Current (A) 

12/24 17 to 100 20 250/500 10 

Max Load 

Current (A) 

12/24 Max 95 20 300/600 10 

12/24 Max 75 15 200/400 15 

12/24/36/48/60 Max 150 80 1250(12) 

2550(24) 

5000(48) 

7500 (60) 

12/24/36/48/60 Max 150 60 900(12) 

1800(24) 

3600(48) 

4500 (60) 


Allowing for 125% oversizing then the required rating of the MPPT is: 

1.25 x 720Wp = 900 W 

From the table we would select the Outback Flexmax60 which has an array rating of 1800W @ 24V 

We could possibly use two of the others e.g. Phocos or Steca. 

MATCHING THE PV ARRAY TO THE MAXIMUM VOLTAGE SPECIFICATIONS OF THE MPPT 

The MPPT typically have a recommended minimum nominal array voltage and a maximum voltage. In the 

case where a maximum input voltage is specified and the array voltage is above the maximum specified, the 

MPPT could be damaged. 

Some MPPT controllers might allow that the minimum array nominal voltage is that of the battery bank. 

However the MPPT will work better when the minimum nominal array voltage is higher than the nominal 

voltage of the battery. The Outback range of MPPT’s requires that the minimum nominal array voltage is 

greater as shown in Table 5. Please check with the MPPT manufacturer because these could vary. 


Table 5 Minimum Nominal Array Voltages (Outback MPPT’s) 

Nominal Battery Voltage Recommended Minimum Nominal Array 

voltage 

12V 

24V 

24V 

36V 

48V 

60V 

It is important that the output voltage of the string is matched to the operating voltages of the MPPT and that 

the maximum voltage of the MPPT is never reached. 

The output voltage of a module is affected by cell temperature changes in a similar way to the output power. 

The manufacturers will provide a voltage temperature coefficient. It is generally specified in V/°C (or mV/°C) 

but it can also be expressed as a % . 

To ensure that the V oc of the array does not reach the maximum allowable voltage of the MPPT the minimum 

day time temperatures for that specific site are required. 

In early morning at first light the cell temperature will be very similar to the ambient temperature because the 

sun has not had time to heat up the module. In the Pacific Islands the average minimum temperature is 20 0 C 

(this could be lower in some mountain areas) and it is recommended that this temperature is used to 

determine the maximum V oc. (Note: If installing in the mountains then use the appropriate minimum 

temperature. Many people also use 0°C, if appropriate for the ar ea). The maximum open circuit voltage is 

determined similar to the temperature derating factor for the power. 

For the worked example Assume the voltage co-efficient is 0.07V/ o C. 

If the minimum temperature is 20 o C this is 5 o C below the STC temperature of 25 o C. Therefore the effective 

variation in voltage is: 

5 x 0.07 = 0.35V 

So the maximum open circuit voltage of the module = 22.1V + 0.35V =22.45V 

Maximum number of modules that you can have in series = 150V ÷ 22.45V = 6.68 this is rounded down to 6. 

So the MPPT will allow between 3 and 6 modules in a string. 

The actual number of modules required was 8.68. If we round down to 8 (since an oversize factor of 10% and 

also worst month for PSH was used) then the array would be 2 parallel strings of 4 modules in series. If we 

round up to 9 then the solution could be 3 parallel strings with 3 modules in series. 


ATTACHMENT 1: : Table showing Peak Sunhrs for various sites and tilt angles. 

Location Peak Sunlight Hours (kWh/m²/day) 

Suva, Fiji Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 

Latitude: 18°08 ′ South 0° Tilt ¹ 6.29 6.2 5.54 4.67 4.05 3.72 3.89 4.44 5.08 6.04 6.32 6.38 5.21 

Longitude: 178°25 ′ East 18° Tilt ² 6.27 5.88 5.55 4.99 4.61 4.38 4.51 4.88 5.22 5.83 6.1 6.41 5.38 

33° Tilt ² 5.95 5.4 5.33 5.03 4.85 4.7 4.8 5 5.1 5.43 5.71 6.12 5.29 

Apia, Samoa Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 


Longitude: 171°46 ′ West 13° Tilt ² 5.31 5.24 5.12 5.32 5.07 5 5.24 5.61 5.85 5.72 5.67 5.45 5.38 

28° Tilt ² 5.13 4.86 4.93 5.38 5.36 5.42 5.64 5.81 5.75 5.36 5.45 5.3 5.37 

Port Vila, Vanuatu Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 



32° Tilt ² 6.38 5.43 5.56 5.39 5.02 4.75 4.98 5.39 5.72 5.83 6.07 6.73 5.61 

Tarawa, Kiribati Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 

Latitude: 01°28 ′ North 0° Tilt ¹ 5.58 5.98 5.99 5.87 5.82 5.7 5.87 6.15 6.52 6.4 6.1 5.5 5.95 


Rarotonga, Cook Islands Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 


Longitude: 159°47 ′ West 21° Tilt ² 5.9 5.82 5.86 5.04 4.56 4.2 4.35 5.07 5.39 5.74 6.11 6.51 5.38 

36° Tilt ² 5.19 5.34 5.62 5.08 4.8 4.49 4.6 5.22 5.27 5.35 5.41 6.11 5.21 


Nuku'alofa, Tongatapu, Tonga Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 



36° Tilt ² 5.35 5.47 5.46 5.14 5.08 4.55 4.68 5.18 5.34 5.65 5.45 6.25 5.3 

Honiara, Solomon Islands Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 



24° Tilt ² 5.91 5.29 5.35 5.59 5.27 5.28 4.99 5.53 5.72 5.88 6.28 6.22 5.61 

Koror, Palau Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 



22° Tilt ² 5.75 5.86 6.06 6.01 5.66 5.03 5.1 5.03 5.3 5.51 5.74 5.54 5.55 

Ponape, Pohnpei FSM Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 


Longitude: 158°13 ′ East 6° Tilt ² 5.12 5.65 5.88 5.72 5.42 5.33 5.51 5.49 5.59 5.33 5.16 5 5.43 

21° Tilt ² 5.43 5.82 5.8 5.55 5.4 5.39 5.53 5.39 5.41 5.39 5.43 5.36 5.49 

Majuro, Marshall Islands Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 



22° Tilt ² 5.83 6.16 5.99 5.62 5.61 5.35 5.35 5.46 5.16 5.25 5.27 5.4 5.53 


Alofi, Niue Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 



34° Tilt ² 6.06 5.4 5.47 5.24 5.24 4.78 5.08 5.29 5.42 5.41 5.35 6.15 5.41 

Nauru Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 

Latitude: 0°32 ′ South 0°Tilt ¹ 5.77 6.24 6.27 6.04 5.99 5.75 5.85 6.25 6.7 6.5 6.12 5.5 6.07 


Vaiaku, Tuvalu Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 


Longitude: 179°13 ′ East 8° Tilt ² 5.14 5.2 5.26 5.37 5.14 4.92 5 5.45 5.71 5.71 5.54 5.22 5.31 

23° Tilt ² 5.09 5.05 5.08 5.43 5.42 5.3 5.33 5.62 5.61 5.49 5.47 5.21 5.34 

Hagåtña, Guam Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 

Latitude: 13°28 ′ North 0° Tilt ¹ 5.33 5.87 6.73 7.12 7.04 6.44 6 5.3 5.42 5.46 5.16 5.05 5.9 


28° Tilt ² 6.41 6.49 6.75 6.4 6.7 6.27 5.76 4.68 5.19 5.78 6.01 6.2 6.05 

Noumea, New Caledonia Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 



37° Tilt ² 5.75 5.8 5.6 5.63 5.03 4.48 5 5.7 6.33 6.38 5.94 7.03 5.72 

Pago Pago, American Samoa Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

Annual 

Average 




29° Tilt ² 5.57 5.22 5.3 5.49 5.4 5.39 5.52 5.77 5.77 5.46 5.75 5.68 5.53 

¹ Monthly Averaged Insolation Incident On A Horizontal Surface (kWh/m²/day) 

² Monthly Averaged Irradiation Incident On An Equator-Pointed Tilted Surface (kWh/m²/day) 

Source: NASA Surface meteorology and Solar Energy 

(http://eosweb.larc.nasa.gov) 


Appendix 1 – Table of Abbreviations and Acronyms 

d.c. 

Direct current 

a.c. 

Alternating current 

AS/NZS Australia Standard/New Zealand Standard 

UL 

Underwriters Laboratory 

ICC 

International Code Council 

NFPA National fire Protection Association 

ASCE American Society of Civil Engineers 

IEEE Institute of Electrical and Electronics Engineers 

Wh 

Watt hours 

kWh Kilowatt hours 

W 

Watts 

W P 

Watts peak 

H 

hours 

V 

Volts 

A 

Amps 

VA 

Volt amps 

Ah 

Amp hours 

DOD Depth of discharge 

C 100 Battery capacity when battery is discharged over 100 

hours 

PV 

Photovoltaic 

MPPT Maximum power point tracker 

PSH Peak sun hours( kWh/m 2 ) 

kWh/m 2 Kilowatt hours/metres squared 

°C Degrees Celsius 

NOCT Nominal operating cell temperature 

T cell-eff the average daily effective cell temperature (degrees 

Celsius) 

T a.day the daytime average ambient temperature for the month 

that the sizing is being undertaken (degrees Celsius) 

f man Derating due to manufacturers tolerance 

(dimensionless) 

f dirt 

Derating due to dirt (dimensionless) 

PWM Pulse Width Modulation 

V oc 

Open circuit voltage (volts) 

V mp 

Maximum power point voltage (volts) 

I sc 

Short circuit current (amps) 

I mp 

Maximum power point current (amps) 

STC Standard test conditions 


III. (Attachment) Letter of derogation # DEVCO/H3/BD/D (2011) 

Letter of derogation # 

DEVCO/H3/BD/D (2011)

The updated tender dossier is available from the following Internet address: 

https://webgate.ec.europa.eu/europeaid/online-services/index.cfmdo=publi.welcome 

The tender dossier is also available from the Contracting Authority at the following internet addresses: 

https://sites.google.com/site/ef2yspsc/tender-dossier or http://www.yapstategov.org/bids.htm 

--- End of Document –

CORRIGENDUM No. 2 - Yap State Government

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