Solar panel buying guide

1. Start with the subsidy rules

If you are claiming the PM Surya Ghar subsidy on a home, two rules come first:

• DCR (Domestic Content Requirement): the panels must be made with cells manufactured in India.
• ALMM: the panel model must be on the government’s Approved List of Models and Manufacturers.

A panel that is not both loses the subsidy, and it cannot be put right after installation. DCR panels cost more per watt than non-DCR, but on a home system the subsidy usually more than covers the difference. DCR and non-DCR panels works through the figures. Without the subsidy, for a business or an off-grid system, non-DCR panels are an option.

2. Choose the technology

	Mono PERC half-cut	TOPCon	Bifacial
What it is	The established mono cell, cut in half to cut losses	A newer N-type cell design	Collects light on both faces
Efficiency	Good	Higher	Depends on the cell
Best for	Most rooftops	Limited roof space	Raised structures over a light surface

Higher efficiency means more watts from the same roof area. On a roof with space to spare, it matters less than price and warranty. See TOPCon panels, mono PERC and half-cut and bifacial panels.

3. Read the datasheet

Datasheet item	What to look for
Rated power (Pmax)	The watts at standard test conditions. Decides the panel count.
Module efficiency	Power from the area. Higher fits more on the roof.
Temperature coefficient of Pmax	How much output falls as the panel heats up. A smaller loss per degree matters in a Punjab summer.
Power tolerance	Should be positive only, so no panel is below its rated power.
Dimensions and weight	For the layout and the structure.
Certifications	The standards the model is tested to, and its ALMM listing.

What matters on a panel datasheet explains each one.

4. Check both warranties

Panel warranties come in two parts, both from the manufacturer:

• A product warranty against defects, in years.
• A performance warranty that the panel will still give a stated share of its rated power after a stated number of years.

Get both in writing, with the manufacturer’s name. A warranty is only as useful as the claims process behind it, so ask who handles a claim locally.

5. Work out how many panels

1. Decide the system size in kW from your bill. The solar calculator does this.
2. Divide the size in watts by the panel’s wattage, and round up. A 3 kW system with 550 W panels needs six panels.
3. Check the roof: about 100 sq ft of shade-free area per kW, including gaps between rows. The roof capacity calculator counts the panels for you.

6. Compare like with like

When quotes differ, check the panels first: make, model, wattage, DCR status and warranties. Two quotes for 3 kW with different panels are different systems. The quote comparison tool and the 50-point quote checklist help.

UTL panels

We supply UTL’s range, from small 40 W panels for lighting kits up to large rooftop modules, including DCR mono and TOPCon models for subsidy systems. The UTL panel catalogue lists each model with its specifications, and UTL compared with other brands sets them against other makers’ published figures.