How to Choose Solar Panels in India (Without Buying on Brand Alone)

The Approved List of Models and Manufacturers is a government-maintained list of solar modules eligible for use in subsidised and government-linked projects. If you are claiming PM Surya Ghar, the modules must be ALMM-listed. This is not a quality preference — it is a condition of the claim.

Balance-of-system components should be BIS-certified. An installer who is vague about either is either not doing subsidised work regularly or is planning to substitute after contract.

Module efficiency is measured at 25 °C. A Jaipur rooftop in May is nowhere near 25 °C — module temperatures well above 60 °C are routine, and every module loses output as it heats.

The temperature coefficient tells you how much. A module losing 0.30% per degree above test conditions will outperform one losing 0.38% per degree in real Rajasthan summer conditions, even if the second has a marginally higher nameplate efficiency. This is the specification most worth reading and the one least often quoted in a sales conversation.

Mono PERC has been the mainstream for years and remains perfectly sound. TOPCon and other n-type technologies are now widely available and generally offer a better temperature coefficient, lower first-year and long-term degradation, and better performance in diffuse light — which matters more in the monsoon than people assume.

Bifacial modules generate from the rear face as well, which is genuinely useful on elevated structures, ground mounts and reflective surfaces, and close to useless flat against a dark roof. Whether it is worth paying for depends entirely on the mounting, which is why the question cannot be answered before the survey.

Modules carry two different warranties and buyers routinely conflate them. The product warranty — typically 10 to 15 years — covers manufacturing defects. The performance warranty — typically 25 to 30 years — guarantees a minimum percentage of rated output at the end of the term.

The performance figure is the meaningful one. A module guaranteed to deliver 87% of rated output at year 25 is a materially better asset than one guaranteed 80%, and the difference compounds across the whole life of the plant.

Modules rarely fail. Inverters do — they are the working electronics in the system, and a fifteen-year-old inverter is an old inverter. Yet buyers who spend a fortnight comparing module datasheets will accept whatever inverter appears on the quote.

Ask about the inverter's efficiency, its MPPT configuration, whether its capacity suits the array's loading ratio, its warranty term and extension options, and — most practically — who services it in Rajasthan and how quickly. An unsupported inverter brand is a five-year problem, not a twenty-five year one.