The success of a microgrid largely depends on the quality of components used right from the generation, transmission and storage.
For example, in the microgird installed at Dharnai, we have used a grade A solar panel with the highest efficiency, which is guaranteed to last 20 years, providing optimum efficiency for 15 years.
If for instance, we had used grade B panels, the amount of upfront cost savings would be a little better, but it will be necessary to replace the entire panels by the end of 10-12 years which would not be so cost effective. So, choosing the right quality of the panels will not only extend the life of the microgrid, but also optimise cost and effectiveness.
Next, is the placement of the panels. Since one of the major benefits of a decentralized microgrid is the high efficiency of generation and nil transmission and distribution losses, one has to make sure the panels are placed in the right manner.
Solar panels need to be placed on a roof which has ample direct sunlight and no shadowing from neighbouring trees or buildings. The panels are usually connected in series or parallel to achieve the optimum voltage and current. So when there is a shadow covering part of the panels on the rooftop, there is a drop in the efficiency of the system close to 10%. Hence, it’s very important to understand how this affects the overall performance.
The solar panels are generally south-facing and inclined at 35-40 degrees so that it receives optimum sun rays all throughout the year. All rooftop sites in Dharnai have been carefully chosen after days of observation and analysis to ensure maximum performance.
Then there is the transmission part, which needs to be efficient, robust and flexible as well. In Dharnai, we have adopted an overhead transmission approach to ensure maximum reachability around the village. Overhead transmission also ensures easy maintenance and quicker installation.
Storage is equally important. In India, the best solution available for long-term efficient storage are the tubular solar batteries, specifically designed for solar technology. Coupled with these batteries are the high-performing pure sine wave inverters, which ensure smooth transfer from the direct current (DC) generated by the panels to the alternating current (AC) which is used in the households of Dharnai.
To ensure that the microgrid is efficient and cost effective in the long run, the final measure is to equip all the households in Dharnai with highly efficient light emitting diodes (LEDs) which consume close to 10-15 watts less than the traditional incandescent and CFL lights.
16 July 2014
All rooftop sites in Dharnai have been carefully chosen after days of observation and analysis to ensure maximum performance. - Photo credit: Ravi Sahani
(Anand Prabu Pathanjali is a Climate & Energy campaigner with Greenpeace India)