Keeps a housing society's solar running with its diesel genset in power cuts
TL;DR Islehold fits a controller into housing societies that have both rooftop solar and a diesel genset, so the panels keep producing during a power cut instead of switching off. The resident association pays a fitting fee and a yearly service plan, and the lower diesel bill pays for both.
Grid-tied solar inverters shut down when grid power fails. That's a safety feature, but it means a society's rooftop plant sits idle at the exact moment the genset is burning diesel.
How big is the gap? A study by the Centre for Science and Environment put genset power at ₹27–33 a unit including capital, against ₹6–9 for rooftop solar, and counted about 90 GW of diesel backup installed across India[1]. CSE also argued that gensets in multi-storey housing should be limited to essential common-area loads[2].
Those figures are from 2017 and we found no newer count.
What it does, in regulatory terms: electrical control equipment fitted by licensed contractors. It adds no generation, sells no power and doesn't touch the society's discom connection.
Islehold is a controller that sits between the society's solar inverters, its genset and the main panel. When the grid drops and the genset starts, it lets the inverters keep running but caps their output so power never flows back into the genset, which would trip it. On a sunny afternoon cut, solar can carry a big share of the common-area load and the genset idles along on less fuel. The controller logs every outage, genset hour and litre estimate, and the managing committee gets a monthly report in rupees.
The seed proposed AI predictive control for microgrids, and we narrowed it. A society with solar, a genset and the grid already is a small microgrid, and the plain control job pays for itself before you need any prediction at all. After that, the software learns outage patterns and genset loading to suggest better maintenance and sizing.
The resident welfare association or the facility-management firm pays, out of the same maintenance fund that buys the diesel. They already sign yearly contracts for genset upkeep and solar cleaning, so one more isn't a stretch.
Islehold charges a fitting fee plus a yearly monitoring plan. We found no published price for a comparable society product, so set your prices in pilots.
Solar on society roofs is common enough now that plenty of committees run both systems. A 3 MWp plant in Yamuna Nagar was commissioned in February 2026 with exactly this kind of solar-genset synchronisation, which tells you the technique has gone mainstream[3]. Hybrid inverters with automatic switching are catalogue items too[4].
There's no public figure for housing societies with both rooftop solar and diesel backup.
Adjacent: about 90 GW of diesel backup was installed in India by CSE's 2017 count, and CSE saw room for up to 3 GW of rooftop solar on new residential societies[1][2]. Treat those as context and expect to build your own count city by city.
Industrial plants already use solar-genset controllers, and the Yamuna Nagar project is one example, though its supplier wasn't named[3]. Inverter brands sell hybrid systems with batteries for homes[4], which dodge the problem a different way at a higher cost.
We found no company selling a packaged controller plus fuel reporting to housing societies. That's the gap.
| Difficulty | Moderate (44/100) |
| Starting capital | ₹1.1–2 Cr |
| Time to launch | 9–12 months |
Every society has its own mix of inverter brands, genset sizes and panel wiring, so each fitting starts with a site survey. The control loop has to be right, because a tripped genset during a cut becomes a committee crisis by dinner time. Sales are slow too, since committees meet monthly and change every year or two.
No power licence, since Islehold adds no generation and sells no power. But you're working in a building's main panel, so safety rules matter.
Building this outside India? The categories above usually have a local equivalent, so check with your own regulator.
Don't let AI run the anti-backfeed control loop. That limit has to be fixed, tested logic, because one tripped genset can lose you the society.
Want to work out the AI layer for Islehold? Talk to Yash →
Here's what can go south -
I like this as a practical services business for an electrical engineer who enjoys site work. It suits cities and suburbs with frequent afternoon cuts and fits badly where outages are rare.
Prove one thing first - measured diesel savings across ten societies that pay back the fitting within two years.
Plan for roughly ₹1.1–2 Cr, covering controller hardware, licensed fitting teams and site surveys.
No power licence, but fitting must be done by a licensed electrical contractor and may need the state electrical inspectorate's approval.
Yes, wherever buildings run solar alongside backup gensets during frequent outages. Check local electrical safety and grid connection rules first.
The free Islehold validation kit has the line-by-line capital breakdown, the effort scoring, the electrical and equipment checklist, a 14-day validation sprint with pass/fail targets, a 90-day launch plan, 10 interview questions for society committees and facility managers, and 5 assumptions to test. Download the kit →
Thinking about building Islehold or something close to it? The hard part is fitting safely across many inverter and genset combinations and proving fuel savings to wary committees, and that's where I can help. If you need a hand, you know where to find me. Talk to Yash →
For illustration only. Names are fictional and ideas hypothetical; sourced facts are real but may be out of date. Nothing here is legal, financial or professional advice, and Yash Khatri is not personally liable for any use of it. Read the full disclaimer.