How to do module selection for a PV plant
The module is the major cost (approx 60% of total project cost) and has variety from less than a USD/Wp to 2 USD/Wp. It is an important element of project as the return on investment totally depends upon this choice. There are choices available between technologies and the decision should be made considering all aspects as full cost and not only the initial capital cost.
For same installed capacity of plant, no of modules increase will further increase the other direct cost like mounting structure, cabling, land development, fencing, security… and impacts indirect cost i.e. system losses, increased O&M / cleaning, more week points for chances of failures etc.
It is evident that the total system cost (excluding O&M, land cost) varies, Module cost increase is partially subset by other direct cost savings. But if Land cost is significant and taken into account, the it will be inverted!.
It is important to understand that low initial cost may not be the best investment choice unless Return on Investment (ROI /IRR /NPV etc.) is calculated on Total system cost (Module, Balance of System, Land lease, system losses etc.), O&M, spare, repair and replacement provisions etc. are taken into calculation.
The next important consideration is the Energy Generation over the life of the project, which will make the decision on financial returns out of investment.
Contrarily to popular understanding, module technologies & efficiencies also impacts the energy generation in practice. Higher efficiency modules operate at lower temperatures captures broad spectrum of light and thus convert more of the sun’s energy to electricity – lower efficiency modules convert it to heat instead.
This is proven by independent researches on various modules and their generation over the years in same conditions and comparison of extra generation with best is given next :
So there is an optimum balance point where the choice should be made on Capex vs other Direct/Indirect costs.
There are comparison scenarios presented to understand the trends. For every project this could be a way be have detailed comparison to form a balanced decision based total cost and yield.