This is one of the most confusing question which most of the end customers face when it comes to choosing solar company to install a Solar PV Plant on rooftop. Answer gets more confusing if you will start evaluating quotations and taking references from govt. nodal agencies to understand how much will it actually cost.
For example if you go to PSPCL (Punjab Nodal Agency) website, the benchmark price is INR 37,000 per kW, if you go to CREST (Chandigarh) website you will find the benchmark price as low as INR 47,000 per kW, IPGCL (Delhi) says INR 42,000 and if you will start searching solar companies on google, then people, they start getting quotations from INR 55,000 per kW to INR 70,000 with end to end solution with various combination of components, after installation services, structures etc. typically for a system size from 3 to 10kW. Now what sounds like cheating end customer is, that very limited companies are actually offering listed price with govt. nodal agencies and if they cannot afford to sell at that price, why they get listed at first place? The answer is, that's how the tendering process of listing vendors works for subsidy based systems. The tendering process promotes L1(cheapest rate) instead of quality based merit list and process is such, even if Tesla reaches India and quotes its price then Mr Musk might also get rejected before even clearing the first stage of eligibility criteria because in tendering process the target is to get lowest price not the best system integrators.
The best way to finalise your installer would be obviously installation quality which purely means workmanship.
What you are expecting from your system and installer since we are talking about an investment for next 25 years! Getting it at dirt cheap price feels good for first few months but after some time results are:-
I am just drafting few very common points which you can keep in mind while evaluating best deal for yourself without compromising basics:
1. If possible, try to visit nearest system installed by the company and try to enquire about service record of the company?
2. How often do installer visits sites for basic maintenance of the system?
3. Delivery timelines.
4. Do installer maintains any service log book- digital or physical?
5. While paying a visit make sure you give close attention to wiring work because that's the most ugly impression if not done properly.
6. Ask for waterproofing measures taken while grouting module mounting structure on roof.
7. Ask for combination of components available, for example it's not at all necessary to go for cheapest option available. Look for the latest technology trends, there are inverters available in market which provide special power optimisers that can enhance your generation for 25 years.
8. Instead of saving bucks, try to come to an agreement with extended warranties or maintenance contracts.
9. Stop believing in subsidy based Solar PV System, waiting for subsidy for indefinite timeframe will not lead your investment anywhere. Instead, go with more efficient monocrystaline modules, more reliable inverters and take your decision with a target of saving your bills for this summer because you are paying your electricity bills everyday without fail.
Take a look at the following link for more pictures.