Hardware · Comparison
Battery only versus solar and a battery together
Updated
Battery-only wins when the roof is useless or forbidden and a cheap night rate is real. Solar and battery together wins when the roof is good and export would otherwise be poorly paid.
The difference that should decide it
Many terraces are the first case. Many semis are the second. Do not buy panels you cannot fit in order to justify a battery you wanted for the tariff. Ignore the brochure finish until you know usable kWh, continuous power, whether the existing solar inverter stays, and who answers in year eight.
A cheaper cell behind a small inverter can win a per-kWh table and still be the wrong machine.
The same house, two scopes
Take a 13.5 kWh pack, cycled about 320 times, at 90% round trip. Charge at 13.0p, and value what comes back at 29.6p. Export given up is priced at 10.0p. There are no panels beside this 13.5 kWh pack, so every unit charged comes off the grid. Delivered energy is about 3888 kWh. After charging cost and lost export, the figure saves about £589 a year. Set that against £6,285 fitted, which is a September 2026 illustration at the temporary 0% residential rate, not a quote. That is a simple payback of about 10.7 years on these assumptions. Nudge the night rate up by 4p and see if you still like it.
In most single-phase houses in Britain, 5 kW sits above the 3.68 kW G98 line, so this wants a G99 application before anyone energises it. Export can still be capped. Agree that before the inverter is ordered. The figure uses 13.5 kWh and 0 kWp, which is enough to tell two quotes apart if they assumed something else.
Pick with the building, not the advert
Where the job is a qualifying install in a home, the 0% rate runs to 31 March 2027 and is due to become 5% after that. This figure prices the work at £6,285 on that basis. It does not apply to a shop, and it does not apply to a battery you buy and fit yourself.
I would not compare a £6,285 headline with another until usable kWh and the fate of any existing inverter match. One option may need a certified installer and the other a wider trade. That is a real difference on the day it fails.
Before a deposit, I would want usable capacity, the warranty counterparty and a G99 note for this 5 kW inverter. The cupboard has to be a place you can stand in, at a temperature the datasheet allows. A five-minute video is not that.
Common questions
Is the price on this page a quote?
No. £6,285 is a September 2026 illustration for a 13.5 kWh example at the temporary 0% residential rate. Your survey replaces it.
Will it stay on in a power cut?
Only if a gateway or essential-load board was designed and paid for. A standard grid-tied battery turns off with the grid. On this 13.5 kWh example the inverter is 5 kW, and backup is still a separate line.
What paperwork should I keep?
Keep the MCS certificate where the job is certified, the electrical certificate, the DNO record, the schematic, the warranty registration and a photo of the schedule. For an illustrated £6,285 job, that folder is part of what you bought.
What if the cheap rate is not 7p?
Then the figure changes. This page used 13.0p as a charge rate and 29.6p as the rate avoided. A smaller gap means a worse payback. Read the live tariff.
Sources
Want a price for your house?
The figures above are a rough guide. An installer still needs to see your fuse board, where the battery will go, and whether you want power during a blackout.