Can I add a battery to my existing solar? What to check before you buy
Yes, most UK solar systems can be upgraded with a home storage battery. The two common paths are adding an AC-coupled battery to your current inverter, or swapping to a hybrid inverter and fitting a DC-coupled battery. The best choice depends on your inverter, space, tariffs and evening usage. Use this guide to check the key points before you buy.
Here's a quick answer
If your existing inverter is working well and under warranty, an AC-coupled battery is usually the least disruptive option.
If your inverter is near end of life or undersized, a hybrid upgrade can simplify the system and improve efficiency.
Size the battery to cover your typical evening and early-morning use. For many homes that’s 5-10 kWh.
What to check on your current system
s1) Inverter type and age
Note the make, model and install date. Most string inverters pair well with an AC-coupled battery. If the inverter is older or near warranty end, a hybrid swap may be sensible.
2) Array size and strings
Knowing your kWp and string layout helps us confirm charge rates and any constraints from shade or orientation.
3) Consumer unit and spare ways (a circuit or a slot)
We’ll check for safe isolation, RCD (residual current device) protection and spare ways for the battery circuits.
4) DNO notification
Installers must notify the Distribution Network Operator. Exports above certain limits may need approval. We handle this for you.
5) Monitoring and apps
Decide whether you want one combined app for PV + battery. Hybrid solutions often give a single dashboard; AC-coupled may mean two apps unless integrated.
Battery sizing (simple method)
Start with evening use. Look at your smart meter app or bills. Estimate the kWh you use from 17:00-23:00, then add a little for early morning.
Common picks:
Flats/low use: 3-5 kWh
Typical homes: 5-10 kWh
Higher use or EV/heat pump: 9-15 kWh
Rule of thumb: aim to use most of the battery most days. Oversizing can slow payback unless you’re on a smart tariff.
AC-coupled vs hybrid upgrade
AC-coupled (add alongside your inverter)
Pros: Minimal disruption, keeps your existing inverter, easy to retrofit, works during inverter warranty.
Cons: Two boxes, slightly more conversion steps. Separate apps unless integrated.
Hybrid inverter + DC battery (swap the inverter)
Pros: One system and one app, efficient PV-to-battery charging, tidy wiring.
Cons: More work on the day, higher upfront cost if the old inverter still has life left.
Smart tariffs and export
Time-of-use tariffs let the battery charge off-peak and discharge at peak.
SEG export pays for what you send to the grid. We set metering so your export is recorded correctly.
Automations can shift charging away from 16:00-19:00 peaks and maximise savings.
Install day and placement
Location: loft, utility or garage with clearances (space around) and good ventilation.
Cabling: neat routes to the consumer unit and isolators.
Safety: correct earthing, labelling and commissioning.
Handover: app set-up, modes explained and warranty details.
Costs and payback (typical ranges)
Most UK retrofits fall in a band that suits 5-10 kWh batteries.
Payback is driven by how much solar you shift to evenings and your tariff. Homes with EVs or heat pumps often see faster returns. We’ll model it on your bills before you commit.
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FAQs
Do I need to replace my existing inverter?
No. An AC-coupled battery usually fits alongside it. If the inverter is old or undersized, a hybrid upgrade may be better value.
Will a battery affect my export payments?
You’ll still receive SEG payments. We configure metering so export is recorded correctly for your supplier.
Can I still add a battery if I have some shade?
Yes. Shade affects panel output, not whether a battery can be fitted. We’ll set sensible charge rates and modes to suit your solar array.