The short version
- Size a battery against a defined backup list, never against the whole house. That single discipline decides whether the budget survives.
- Lithium (LiFePO4) costs more on day one and usually less per usable cycle. Tubular lead-acid costs less up front and gives you less usable energy for longer-term maintenance.
- Rated capacity is not usable capacity. Depth of discharge is where most quotations mislead.
- Under net billing, storage stopped being a comfort purchase and became an arithmetic one — but only if you have real evening load.
- Fusing, isolation and ventilation are not optional extras. They are the difference between a battery bank and a fire.
Batteries are the most oversold and most badly specified part of a solar system in Pakistan. They are also the part that has changed the most since the 2026 net billing rules landed. Here is how to size one properly, and how to read a battery quotation without being taken for a ride.
How do I work out what size battery I need?
Notice what happened at the bottom of that example. Six kilowatt hours of actual demand became roughly seven and a half kilowatt hours of battery to buy, because you cannot use every drop of a battery’s rated capacity without ruining it. That gap is where most quotations quietly fail, and where most disappointment comes from three months after commissioning.
Two more things to hold in mind. Air conditioning dominates any backup list it appears on, so decide honestly whether you need one running or whether fans will do. And a battery sized for four hours is not sized for eight — doubling the hours doubles the bank.
Tell us your backup list and we will size the bank
Send us the circuits that must stay live and for how long. You will get a battery size, a chemistry recommendation and an honest view on whether storage is worth it for your house at all.
Lithium or tubular lead-acid?
Both are sold widely in Pakistan and both have a legitimate place. The difference is not quality in the abstract, it is what you are optimising for.
| Lithium (LiFePO4) | Tubular lead-acid | |
|---|---|---|
| Price on day one | Higher | Lower |
| Usable share of rated capacity | Most of it | Considerably less |
| Cycle life | Long | Shorter |
| Weight and footprint | Light, compact | Heavy, bulky |
| Maintenance | None | Periodic, and it matters |
| Ventilation | Normal room ventilation | Needs a properly ventilated location |
| Best when | You will keep the system for years | The budget is genuinely fixed today |
For most households buying in 2026, lithium is the sensible default. The honest exception is a buyer whose budget is hard-capped now and who understands they are accepting a shorter life and real maintenance in exchange. We will quote either, and we will tell you which one we would put in our own house.
Why depth of discharge decides everything
A battery’s rated capacity is a laboratory number. What you can actually take out of it, repeatedly, without destroying its life, is a fraction of that. Drawing a lead-acid bank too deep shortens its life dramatically. Lithium tolerates much deeper discharge, which is why a physically smaller lithium bank can deliver the same usable energy as a far larger lead-acid one.
This is why comparing two quotations on rated kilowatt hours alone is meaningless. Ask every supplier the same question: how many usable kilowatt hours does this give me, and at what depth of discharge? A supplier who cannot answer that is quoting a price, not a design.
Do batteries actually pay under net billing?
Under the old net metering arrangement, a surplus unit exported to the grid came back at the same value, so there was almost no financial reason to store it. Batteries were bought for comfort during load shedding, and that was fine.
Net billing changed the arithmetic. Exported units are now credited at a regulated rate well below the retail tariff, while the units you buy back after sunset still cost the full retail price. Storing a unit rather than selling it captures that spread. We explained the mechanism in net metering to net billing.
That said, this is not a universal yes. If nearly all your consumption happens while the sun is up, a battery mostly sits there being expensive. The deciding factor is your evening load, which is why we read six months of bills rather than one, and why we sometimes tell people not to buy a battery at all.
Not sure whether a battery is worth it for your house?
Send your last three bills and tell us roughly what runs after sunset. We will give you a straight yes or no.
The safety work a cheap quotation removes
Battery systems store a great deal of energy in a small space. The installation details that keep that safe are invisible, unglamorous, and the first thing to disappear when someone is competing on price.
- Correctly rated DC fusing and isolation — so a fault can be cleared and the bank can be safely disconnected.
- Cable sized for the real current — battery circuits carry high currents at low voltage, which is exactly where undersized cable overheats.
- A suitable location — ventilated, dry, temperature-sensible, and not a cupboard chosen because it was convenient.
- Labelling and isolation points — so whoever works on it in five years knows what they are touching.
Ask to see these items itemised. If the quotation says “battery and accessories”, you do not have a specification, and the same pattern shows up across the rest of the system — which we covered in what a solar system really costs.
Solar batteries: questions people actually ask
How do I work out what size battery I need?
Lithium or tubular lead-acid, which is better?
Why does depth of discharge matter?
Do batteries make financial sense under net billing?
What safety work should a battery installation include?
The bottom line
Start from the backup list, not the brochure. Insist on usable kilowatt hours rather than rated ones. Choose the chemistry deliberately rather than by price alone. And make sure the boring safety items are on the page. Do that and a battery is a sound investment under the current rules. Skip it and you will buy one twice.
Get a battery sized properly for your house
A free survey, a defined backup list, usable kilowatt hours stated in writing, and a recommendation you can hold us to. If you do not need storage, we will say so.
