Small-town households buy the evening, not the kilowatt

Most rooftop solar in India is sold with a spreadsheet. A household's monthly units are taken from its bill, divided by what a kilowatt of panels generates in that region, and the result becomes the recommended system size, with a payback period in years printed at the bottom. The method is tidy and it is not wrong. In the towns where Dhruvanta sells most of its systems, I have found that it answers a question few of our customers are asking.

The households we serve in places such as Bareilly, Hajipur, Sagar and Dharmapuri do care about their bills. But when our researchers sit with them, the conversation turns quickly to the evening. Will the fans run if the supply goes at eight? Can the children study after dinner? Will the voltage drop so far that the refrigerator's stabiliser clicks off again? For a family that has owned an inverter for fifteen years, electricity is judged first by whether it is there when needed, and only then by what it costs.

My argument is that product teams selling solar to small-town India should design and size for the evening, not for the kilowatt. That means fewer purely grid-tied systems sold on payback and more hybrid systems with storage sized to the hours that matter, even when they cost more and pay back more slowly on a spreadsheet.

What the inverter logs showed

Dhruvanta has an unusual research asset. Many of our inverters are connected to our app, and their owners have agreed to share anonymised operating data with us. That data shows when the grid fails, for how long and at what voltage supply returns. In 2022 we studied a year of data from the 60,000 inverters then connected, across 180 towns.

The headline finding was encouraging and expected: in most of those towns total outage hours had fallen substantially over three years. The second finding changed our product plan. The outages that remained were not spread evenly through the day. In a large share of towns they clustered between about six in the evening and eleven at night, when demand on local networks peaks, and many were brief interruptions or sharp voltage sags rather than long cuts. A household might lose supply for only forty minutes in a week, but those forty minutes fell during dinner and homework.

A grid-tied rooftop system without storage does nothing for those minutes. It generates during the day, exports what the house does not use and, for the safety of line workers, shuts down when the grid fails. A household that bought one on the strength of its payback period discovered that the new system did not help on the evenings that had always troubled it, and that its old inverter battery was still doing the work. Several early customers asked us why the solar system was off during a power cut. They had not misunderstood the product. We had misunderstood them.

Size the system to the evening

We now begin every residential conversation with the evening rather than the bill. A retailer using our app asks what the household needs to keep running during an outage, for how long and at what times. The answer sets the battery and inverter size. The bill then sets the panel capacity, within what the roof and the household's sanctioned load allow.

The result is often a smaller array and a larger battery than the spreadsheet would recommend. A household using 250 units a month might once have been offered a three-kilowatt grid-tied system. Today it may be offered a hybrid system with two kilowatts of panels and enough storage to carry fans, lights and a refrigerator through a typical evening interruption. The spreadsheet payback is longer. The household's satisfaction, measured by service calls and by referrals, is clearly higher. Among systems sold in 2025–26, hybrid customers referred new buyers at about one and a half times the rate of grid-tied customers.

There is a counter-argument, and I take it seriously. Storage adds cost, and batteries wear out long before panels. A household on a tight budget may be better served by the cheapest grid-tied system the subsidy covers, keeping its existing inverter for backup. In towns with dependable evening supply, that is exactly what we recommend. I am also aware that a company which sells batteries has an interest in recommending them, so I have asked our research team to report to the board each year the share of conversations in which we advised against storage. In 2025–26 it was 37 per cent.

Tariffs may strengthen the case for designing around the evening. As smart meters spread, several states are moving towards time-of-day tariffs that would make evening electricity dearer than daytime electricity. A system that stores daytime generation for the evening would then save money as well as provide comfort. I would not sell a system on a tariff that has not yet been notified in a customer's state, but I would design products able to benefit from one.

Discovery that a retailer can repeat

None of this came from a national survey. It came from people sitting in homes and shops in towns where we have no office, and from data that only an installed base can provide. The discipline I ask of our product teams is that every insight must be repeatable at a retailer's counter. If a finding cannot be turned into a question a retailer can ask in two minutes, it has not yet become product knowledge.

That is why our sizing starts with four questions on a retailer's phone rather than a bill upload. It is also why our product managers spend four days a quarter in the field, and why I still go myself. On a visit to a retailer in Hajipur last year I watched him explain the difference between a grid-tied and a hybrid system using a ceiling fan and a torch. His explanation was clearer than our brochure, and we now use it in training.

Small-town India is often described as price-sensitive, as if that settled the matter. In my experience it is value-sensitive in a precise way. A household will pay more for a product that solves the problem it actually has, and it will resent a cheaper product that solves a problem it was told it had. Our job is to find out which evening matters to a family before we sell it a kilowatt.