Analysis · Memo
The VAT deadline is real and it is not a reason to panic-buy
Updated
The zero rate running to 31 March 2027 is a genuine timing fact. A badly sited battery bought in a hurry is still a bad battery.
The claim, without the fog
Use the window to get two surveyed quotes, not to accept the first lead form that mentions the date. This is a decision about paperwork, money or safety. Write down the usable kWh, the inverter size, and who services the pack before you compare two prices.
Take a 5 kWh pack, cycled about 300 times, at 90% round trip. Charge at 7.0p, and value what comes back at 28.4p. Export given up is priced at 8.0p. There are no panels beside this 5 kWh pack, so every unit charged comes off the grid. Delivered energy is about 1350 kWh. After charging cost and lost export, the figure saves about £278 a year. Set that against £3,650 fitted, which is a September 2026 illustration at the temporary 0% residential rate, not a quote. That is a simple payback of about 13.1 years on these assumptions. Nudge the night rate up by 4p and see if you still like it.
What the rules actually bite on
In most single-phase houses in Britain, 3.6 kW is in the band where G98 connect-and-notify is often enough. Export can still be capped. Agree that before the inverter is ordered. The figure uses 5 kWh and 0 kWp, which is enough to tell two quotes apart if they assumed something else.
Notice 708/6 is the document. The zero rate on qualifying home installations runs to 31 March 2027, then the notice points to 5%, not a bounce back to 20%, unless the law changes. A deposit can pull the tax point forward. On an illustrated £3,650 job, ask how the invoice will be dated.
What I would do next
I would not sign off a 5 kWh install from a video call. Someone has to open the consumer unit. Photograph the board, the meter and the wall you have in mind.
Then get two written scopes. If they describe different machines, you do not have two quotes yet.
Before a deposit, I would want usable capacity, the warranty counterparty and a G98 note for this 3.6 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. £3,650 is a September 2026 illustration for a 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 5 kWh example the inverter is 3.6 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 £3,650 job, that folder is part of what you bought.
What if the cheap rate is not 7p?
Then the figure changes. This page used 7.0p as a charge rate and 28.4p 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.