Charge and discharge schedules for home solar batteries under ToD tariffs
TL;DR Lullcharge is scheduling software for homes that already have rooftop solar with a hybrid inverter and a battery. It decides when the battery fills up and when it runs the house, so your evening use dodges peak rates. Inverter brands license it and bundle it into their own apps.
Time-of-day pricing is coming to Indian homes. Rules notified in 2023 make solar hours 10–20% cheaper than normal and peak hours 10–20% dearer, and they kick in for a household as soon as it gets a smart meter[1]. Most states missed the original dates though, and a 2026 draft pushes the deadline for homes to April 2028[2].
Homes with a solar battery are badly placed for this. The installer sets the battery once, usually to sit full in case of an outage, so it rarely discharges in the evening peak and may even recharge from the grid at peak rates.
What do the inverter apps say about it? Nothing. The monitoring apps on popular inverters show generation and alerts and stop there[3].
What it does, in regulatory terms: consumer energy-management software. It changes settings on an inverter that already carries BIS registration. It is not a meter, a licensee or a power trader.
Lullcharge reads the household's tariff, tomorrow's solar forecast and the past fortnight of load, then writes a daily plan to the inverter - how much charge to hold back for outages, when to discharge and when grid charging is allowed. The homeowner gets one slider, from "most backup" to "most savings". Every month it shows the rupee difference against the installer's default setting.
The seed pitched AI that orchestrates home renewables for grid stability. We reframed it, because India has no market that pays a household for flexibility, so the grid-stability case pays nobody yet. The bill-saving case does, once ToD reaches the home. A discom demand-response programme can come later, when one exists.
Lead-acid inverter batteries are out of scope. Cycling them daily shortens their life and the savings won't cover that.
The homeowner gets the savings but won't pay a separate subscription for a few hundred rupees a month. I wouldn't either.
So the payer is the inverter or battery brand, which licenses Lullcharge per connected unit and sells "smart savings mode" as a reason to buy its hybrid model. Rooftop installers are a second channel and can offer it at handover. There's no public price for a comparable feature in India.
The 2023 ToD rules set out the solar-hour discount and peak premium for homes[1], and a smart-meter install switches them on. Ember's April 2025 analysis argues household flexibility will matter, with homes expected to use about 31% of India's power by 2031-32[4]. And hybrid inverters with apps and grid export are now standard catalogue items[5].
There's no public count of Indian homes with hybrid solar and a battery, and no figure for battery scheduling as a market. The firmest signal is regulatory - every smart-metered home moves to ToD billing on installation[1].
Adjacent: households are projected at about 31% of national demand by 2031-32[4]. Treat that as context, not as your market.
One big Indian inverter brand ships a monitoring app with alerts and analytics, and sells hybrid systems that switch between solar, battery and grid on their own[3][5]. Its pages don't mention tariff-aware scheduling. Overseas, inverter makers and retailers bundle similar optimisers, but we found no Indian product sold this way.
The gap is a brand-neutral scheduler that Indian inverter companies can license instead of building.
| Difficulty | Moderate (33/100) |
| Starting capital | ₹45–80 L |
| Time to launch | 6–9 months |
The algorithm is the easy bit. The hard bit is getting write access to inverters, because each brand has its own protocol and few will open it to a startup without a pilot. State tariffs also differ in peak windows and rates, so the tariff library needs constant upkeep.
No power licence, because Lullcharge only changes settings on an inverter the household already owns. The rules that matter belong to your partners and the tariffs.
Building this outside India? The categories above usually have a local equivalent, so check with your own regulator.
Don't trust AI to override the homeowner's backup choice or the inverter's safety limits. The slider and the hardware protections win every time.
Want to work out the AI layer for Lullcharge? Talk to Yash →
Here's what can go south -
Worth a look for a small team with embedded and energy-tariff skills. If you're hoping for direct-to-consumer subscriptions then it's a poor fit, honestly.
Before you raise money, get one inverter brand to give you write access and show a 30-home pilot where the battery covers most of the evening peak without eating into outage reserve.
Plan for roughly ₹45–80 L, mostly on embedded engineering, inverter integrations and a state tariff library.
No power licence, because you only change settings on an inverter that's already BIS registered. You need homeowner consent under the DPDP Act.
Yes, wherever homes have batteries and time-of-day tariffs. Many markets already have these tariffs, so check local data rules and partner protocols.
The free Lullcharge validation kit has the line-by-line capital breakdown, the effort scoring, the BIS and tariff checklist, a 14-day validation sprint with pass/fail targets, a 90-day launch plan, 10 interview questions for inverter brands and homeowners, and 5 assumptions to test. Download the kit →
Thinking about building Lullcharge or something close to it? The make-or-break step is persuading one inverter brand to open its control protocol to you, and that's a conversation I'm glad to help you plan. 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.