M&V Solar Water Heating Guideline - Eskom
M&V Solar Water Heating Guideline - Eskom
M&V Solar Water Heating Guideline - Eskom
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Measurement and Verification Standard <strong>Guideline</strong> for Low Pressure <strong>Solar</strong> <strong>Water</strong> <strong>Heating</strong> Systems v1r1<br />
The tested evacuated tubes collectors have high operating temperatures, namely<br />
between 90 – 130 o C, heat loss coefficient is above 2 W/m 2 .K, and optical efficiency<br />
of 0.65. These collectors are ideal for space cooling and heating and for process<br />
heat.<br />
Figure 1:. Collector Output Efficiency Curves measured for several types of solar collectors<br />
available in South Africa as a function of (Tm – Ta ) where: Tm - average collector<br />
temperature and Ta - ambient temperature. Source [3]<br />
Low Pressure <strong>Solar</strong> <strong>Water</strong> Heater Roll-out as supported by ESKOM and the South African<br />
Government, initially will be based on mainly imported SWH systems [2]. According to the<br />
Energy Minister Ms. Dipuo Peters on the opening of the one of the first roll-outs at<br />
Winterveldt (Tshwane) , “the units installed there were imported, as would be the case with<br />
the first 200 000 units installed through the programme, as the country gears up its<br />
manufacturing capacity towards SWH” [2]. The SWH units installed at Winterfeldt were<br />
based on evacuated tubes collectors and should perform as shown in Figure 1. One could<br />
expect that the rest of systems installed initially will be similar.[5]<br />
3.2.2 Collector Orientation<br />
To achieve maximum performance of the SWH system the collector should be facing ideally<br />
in the equator i.e. in the North direction in South Africa. Roofs and houses position toward<br />
North does not always allow this rule to be observed. Deviations from North up to 45 0 will<br />
reduce the solar harvesting insignificantly (less than 10%). This is illustrated on the chart<br />
shown in Figure 2., where positioning of a house is shown. The size of the suns pointed at<br />
9