Is Rooftop Solar Worth It in Bengaluru? An Honest Look at the Numbers

Solar quotes tend to arrive with optimistic generation figures and a payback period that assumes everything goes right. Here is how we work it out on a survey, including the cases where the answer is no.

What Bengaluru roofs actually generate

Bengaluru gets good but not exceptional irradiance, and the monsoon months pull the annual average down. A well-oriented, unshaded 1kW system here generates roughly 1,300 to 1,500 units a year — around 4 units a day averaged across the year, more in February to May and considerably less in July and August.

If a quote assumes 5 units per kW per day year-round, it is describing a best-case day rather than an average, and the payback figure built on it will be optimistic by roughly a third.

Orientation and shading matter more than panel brand

South-facing is best. East or west costs you 10 to 15 percent. North-facing rarely justifies the investment.

Shading is worse than most people assume because of how panels are wired in series — a single shaded panel can drag down an entire string. A water tank, a parapet wall or a neighbour's tree that shades one corner for two hours a day can cost far more than that fraction of output suggests. This is the single biggest reason we tell people their roof is not suitable.

A realistic example

Take a home consuming 300 units a month with a 3kW system on a clear, south-facing roof. Expect around 4,200 units a year, offsetting the majority of consumption depending on how much is used during daylight hours.

At current BESCOM residential slab rates, that is a meaningful annual saving against a system cost in the ₹1.8 to ₹2.4 lakh range before subsidy. Payback typically lands between five and seven years, against a panel life of twenty-five. The inverter will need replacing once in that period, and a realistic calculation includes it.

When we say no

We have talked customers out of solar in these four situations, and we would rather do that than install something that disappoints:

• Significant shading that cannot be removed — the numbers rarely work
• A rented property, or one you plan to sell within four or five years
• Very low consumption, under about 150 units a month, where absolute savings stay small
• A roof needing waterproofing or structural work first — do that before mounting anything on it

Grid-tied, hybrid or off-grid

Grid-tied gives the best return but shuts down during an outage, which surprises people. Hybrid adds a battery so essentials keep running through a cut, at meaningful extra cost. Off-grid only makes sense where there is no reliable grid connection at all.

For most Bengaluru homes with reasonable supply, grid-tied is the better financial decision; hybrid is worth the premium in areas with frequent or long outages.

What to ask any vendor

Ask for the generation estimate in annual units, not daily peak. Ask whether the payback calculation includes an inverter replacement. Ask who handles the net-metering application. And ask for a shading analysis rather than a glance at the roof from the gate.

Our site survey covers all of this, is free within Bengaluru, and you keep the written report regardless of whether you buy from us.