Most Indian homes with backup are running a tubular lead-acid battery in a corner, topped up with distilled water every few months and replaced every few years. Lithium changes that arrangement — but only if it is sized properly. An undersized pack fails you during the outage you bought it for, and an oversized one is money sitting idle. The useful question is what you want to keep running, and for how long.
Capabilities
Lithium packs to replace a tubular inverter battery — no water topping, no ventilation requirement, no capacity quietly bleeding away between outages.
Rooftop solar paired with storage so daytime generation covers evening load instead of being exported cheaply and bought back at retail rates.
Sizing starts from what you want backed up — fans, lights, router, fridge, or the whole house with the AC — and for how many hours. The kWh figure follows from that, not the other way round.
LFP chemistry and a sealed enclosure mean no fumes, no noise and no dedicated battery room, so it lives where it is convenient rather than where it is tolerable.
A pack that holds usable capacity for years of light cycling, which is the duty cycle most home backup systems actually see.
Charge level, backup time remaining and consumption history, so you know where you stand before the power goes rather than after.
Where it applies
Stated as the problem first, because the system is only worth specifying once the problem is.
Run the numbers
Every recommendation on this page comes down to arithmetic. Here is the same arithmetic, with your numbers instead of ours — including the cases where the answer is no.
Start from what you want to keep running during an outage, and for how long. The size follows from that — and once you have a size, the comparison against a tubular battery becomes arithmetic.
Estimated saving
Pack you need
3.1 kWh
2.8 kWh delivered at the socket. The tubular equivalent is about 3 × 150Ah units, because it should not be run as deep.
An estimate from your inputs, not a quotation. Sizing also depends on your existing inverter and wiring, which is worth a look before anyone quotes.
Sizing. Usable energy = load × hours ÷ 85% inverter efficiency. That is then grossed up by the depth each chemistry can safely be taken to — 90% for lithium, 60% for tubular. Using one figure for both would understate the tubular bank a buyer actually has to purchase.
Ownership cost counts replacements over the period, rounded up, at the prices you enter. Tubular is priced per 150Ah (≈1.8 kWh) unit and rounded up to whole units, because that is how it is sold.
Solar self-consumption values surplus at your retail tariff, on the basis that stored energy displaces a unit you would otherwise buy back in the evening. If your discom pays a good feed-in rate, the real gain is the difference between the two rates, not the full tariff — so treat this line as an upper bound.
Not included: water topping and maintenance on tubular, the ventilated space it needs, capacity fade between replacements, or any installation cost. These mostly favour lithium and are left out to keep the comparison conservative.
Further reading
Questions
Home Energy
Send us the bill, the load list or the duty cycle. We will come back with a size, a cost and the arithmetic behind both — including the cases where the answer is that you do not need us.