The hidden costs of a home battery
Check whether your quote includes the inverter, backup equipment, cabling, electrical work and the network paperwork. Each item below can change the result; ask the installer which apply to your home. Where a rule applies, we quote the source.
1. VAT is changing
HMRC states that the reduced VAT rate of 5% applies from 1 April 2027 onwards. Valid from 1 April 2027.
“From 1 April 2027 onwards these will revert to the reduced rate of VAT of 5%.”Source: gov.uk, read 19 October 2026
If you are planning an installation close to that date, check which VAT rate your quote assumes.
2. Buying the hardware yourself
Supplying energy-saving materials without installing them is standard-rated.
“However, if you supply energy-saving materials without installing them your supply will be standard-rated.”Source: gov.uk, read 19 October 2026
3. Export payments need the right paperwork and meter
SEG requires installation and installer certification through MCS or an accredited equivalent.
“certified through the microgeneration certification scheme (MCS) or a scheme accredited as equivalent”Source: gov.uk, read 19 October 2026
SEG requires a meter capable of half-hourly export readings.
“meter capable of providing half-hourly export readings”Source: gov.uk, read 19 October 2026
Without these, the export side of your sum may be zero. That is why the calculator asks for your export rate separately.
4. A new inverter
A DC-coupled battery usually shares a hybrid inverter with the panels, which can mean replacing an inverter that still works. An AC-coupled battery brings its own. Ask whether the quote includes an inverter, and what its warranty is.
5. Installation extras
Scaffolding (for work on the roof side), a consumer unit upgrade and extra cabling are often priced separately. Ask for them as separate lines so you can compare like with like.
6. Energy lost in the battery
Some energy is lost every time a battery charges and discharges. Some datasheets state this as round-trip efficiency; check which path it covers (for example solar to battery to home) because makers measure it differently. Our calculator includes it, so a kWh from the battery costs a little more than a kWh going in.
7. Warranty conditions
Battery warranties usually have a time limit and sometimes an energy throughput limit, with a minimum capacity at the end. Our battery guides quote these terms from the manufacturers where we have checked them.
8. Notifying your network operator
For the described microgenerator notification route, the installer must notify the DNO within 28 days.
“Your installer must notify the DNO within 28 days”Source: ssen.co.uk (PDF, page 44), read 19 October 2026
This is normally the installer’s job, but make sure the quote says so.
Next: how to choose an installer.