Solar panels (modules)
Mounted on the roof facing sun (usually south in India). Roughly 1 kW needs about 8–10 m² of clear roof, depending on panel type and spacing.
Homeowner guide
Plain explanation for families who want lower electricity bills — panels, inverter, and net metering — not jargon for engineers. APSPDCL / TGSPDCL examples apply the same idea as other DISCOMs nationwide.
Solar panels on your roof turn sunlight into DC electricity. An inverter converts it to AC for your home. When you generate more than you use, the extra units go to your DISCOM grid through a bi-directional (net) meter. When you need more than you generate (evening, cloudy day), you draw from the grid as usual.
Most homes under PM Surya Ghar use on-grid systems — no big battery required. You stay connected to the grid and your bill reflects units imported minus units exported (as per your state DISCOM rules).
Main parts
Mounted on the roof facing sun (usually south in India). Roughly 1 kW needs about 8–10 m² of clear roof, depending on panel type and spacing.
Converts panel DC to household AC. For subsidy, equipment should follow MNRE / ALMM rules via an empanelled vendor. How to size and specify one: choosing an inverter.
Your DISCOM installs a bi-directional meter after inspection. This links your plant to billing and subsidy commissioning. Process details differ by utility — see net metering in India.
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Night: Panels produce nothing. You use grid power. Your daytime surplus (if any) has already reduced what you owe over the billing cycle under net metering.
Cloud / rain: Generation drops but does not stop completely on light overcast. Annual estimates already assume real weather — not perfect sun every day.
Power cut: Standard on-grid systems shut down for safety (they must not feed a dead grid). They do not give backup like a battery/inverter home UPS unless you add a battery or hybrid system — which is a different product and usually outside the simple subsidy path.
Most homeowners assume a shadow across one corner of the array costs them that corner. It usually costs much more, and understanding why will save you from a disappointing installation.
Panels are wired together in a series string, so current has to pass through each module in turn. When one module is shaded, it restricts what the whole string can deliver — rather like a narrow section in a pipe limiting flow along its whole length. A single water tank shadow, one parapet wall or one overhanging branch can therefore pull down the output of every panel wired with it.
Three things follow from this:
Layout also matters more than brand here. Keeping the array clear of tank and parapet shadows, and leaving room to walk around it for cleaning, generally does more for lifetime output than upgrading the panel model.
Two houses with the same 3 kW system in the same city can produce noticeably different amounts. Sunshine hours are only part of it.
Temperature. This is the counter-intuitive one. Modules are rated at a standard cell temperature and lose efficiency as they get hotter, so a very hot bright location can underperform a milder one with similar sunlight. It is also why a mounting structure raised enough for air to move beneath the panels does real work, and why an inverter in full afternoon sun may throttle its own output to protect itself.
Orientation and tilt. South-facing is the general rule in India, but a modest deviation matters less than most people fear, and a west-facing array can suit a household whose load peaks in the late afternoon.
Soiling. Dust, pollen and industrial particulate reduce output, and a thin even film costs several percent without ever looking dirty enough to notice. In dry and dusty regions this needs a routine; in heavy-rainfall regions rain does much of the work.
Local climate pattern. Monsoon timing differs across the country, and in much of the south the main cloudy season falls at a different time of year from the north. A generation estimate borrowed from a national template can be right on the annual total and wrong about every month.
Ageing. Output declines slowly over the system's life — a small annual percentage, which is normal and should already be inside any long-term projection.
Rooftop solar is low-maintenance, not no-maintenance, and quotations rarely spell out the ongoing part.
An installer measures shade and structure on site. Our online check only answers the money question first. Because that site visit is also where quotes start to diverge, it is worth knowing what to ask an installer before you invite one, and roughly how many panels a given capacity needs.
Before that visit, two numbers are worth working out yourself: how much shadow-free roof area you actually have once tanks, stair room and parapet shadow are deducted, and how many units a kW generates in your part of India. Together they tell you whether a proposed capacity is realistic.
| Monthly bill (approx.) | Often discussed size | Roof (ballpark) |
|---|---|---|
| ₹1,500 – ₹2,500 | 2 kW | ~16–20 m² |
| ₹2,500 – ₹4,000 | 3 kW | ~24–30 m² |
| ₹4,000+ | 4–5 kW | ~35–50 m² |
Subsidy for residential central CFA caps in a way that 3 kW often hits the ₹78,000 ceiling — larger plants can still make sense on high bills, but extra kW do not increase that central cap.
Indicative pricing by size: 1 kW · 2 kW · 3 kW · 5 kW · 10 kW. If your bill is driven mainly by cooling, read solar panels for an AC before sizing. On equipment and upkeep: mono vs poly panels and maintenance. If you want power during outages rather than a lower bill, see on-grid vs off-grid vs hybrid.
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Roughly 8 to 10 square metres of clear unshaded roof per kilowatt, depending on panel type and the spacing needed between rows. A typical 3 kW residential system therefore needs somewhere around 25 to 30 square metres genuinely free of shadow from water tanks, parapets, stair rooms and neighbouring buildings, plus room to walk around the array for cleaning.
Because panels are wired together in a series string, so current passes through each module in turn and a shaded module restricts what the whole string can deliver. One water tank shadow, parapet wall or overhanging branch can therefore reduce output across every panel wired with it, not just the panel it falls on. Where shade is unavoidable, module-level electronics or multiple inverter inputs limit how far the effect spreads.
Generation falls under cloud but does not stop entirely in light overcast conditions, and a sound annual estimate already assumes real weather rather than perfect sun. At night the panels produce nothing and you draw from the grid as usual, with any daytime surplus already having reduced what you owe over the billing cycle under net metering.
Not for the standard grid-tied system that most households install, which uses the grid rather than a battery to balance day and night. A battery is only needed if you want power during outages, since a grid-tied system shuts down in a power cut as a safety requirement. Adding storage is a separate and more expensive proposition with quite different economics.
Yes, which surprises many people. Modules are rated at a standard cell temperature and lose efficiency as they heat up, so a very hot bright location can produce less per kilowatt than a milder one with similar sunlight. This is why a mounting structure raised enough for airflow beneath the panels is worthwhile, and why an inverter should be sited in ventilated shade rather than full afternoon sun.
It is low-maintenance rather than no-maintenance. Expect periodic cleaning with plain water and a soft brush, more often in dusty or industrial areas, keeping vegetation clear of the array, and watching monthly generation against the same month a year earlier so a faulty string is caught early. Over twenty years you should also expect one inverter replacement, since panels typically outlast the inverter.