RETROFIT BATTERY STORAGE
Retrofit BESS: How to Add Battery Storage to Your Existing Solar PV System
Already have solar panels? Find out how retrofitting a battery storage system can dramatically improve your returns and energy independence.
Tens of thousands of commercial solar PV systems installed across the UK in the 2010s are now operating without battery storage — generating electricity that is exported to the grid at low rates while their owners still pay peak prices for evening energy. Retrofitting a BESS changes that equation entirely.
Why Businesses With Existing Solar Are Missing Out
When commercial solar PV was first widely adopted, battery storage was expensive and the technology was immature. Most systems were designed purely for daytime generation — export what you do not use, import from the grid the rest of the time.
Today, that model is far from optimal. Battery storage costs have fallen by over 80% in the last decade, export tariff rates remain low, and grid electricity prices have been persistently high. A business with a 100kWp rooftop solar array installed in 2015 may be exporting 40-60% of its generation at rates of 5-15p/kWh whilst paying 25-35p/kWh to import electricity in the evenings.
AC vs DC coupling
Two approaches to retrofit
AC-Coupled Retrofit (Recommended)
The battery and its dedicated inverter/charger connect on the AC side of your existing installation — after your solar inverters. Works with virtually any existing inverter brand. No changes to your existing solar equipment required, preserving warranties and minimising cost.
DC-Coupled Retrofit
Connects the battery directly to the DC side of your solar array, before the inverter. Requires replacing your existing inverters with a hybrid system. More efficient but more disruptive. Novalux Solar will assess whether the efficiency gain justifies the additional cost for your specific system.
The process
How a retrofit works
Site Assessment — Review existing system docs, inverter specs and half-hourly meter data
Financial Modelling — 25-year cashflow with payback period, NPV and annual savings
DNO Application — G98/G99 notifications and protection relay requirements handled
Installation — NICEIC-accredited team installs battery, inverter/charger and monitoring in 1-3 days
Commissioning — Charge/discharge strategy optimised for your tariff and demand profile
What Systems Are Compatible?
The great majority of commercial solar PV systems installed in the UK are compatible with AC-coupled battery retrofit. This includes systems using inverters from SolarEdge, SMA, Fronius, Huawei, ABB, Sungrow and most other mainstream commercial inverter manufacturers.
Novalux Solar has particular experience retrofitting BESS to older string inverter systems common on rooftop installations across agricultural, manufacturing and distribution sites in Wales and the West Midlands — many installed in the Feed-in Tariff era and ideal candidates for battery upgrades.
FiT recipients note: If your existing solar system is still receiving Feed-in Tariff payments, adding a battery does not affect your FiT entitlement — provided the installation is carried out correctly and the relevant notifications are made.
Retrofit BESS Across the UK
Novalux Solar is based in Skenfrith, Monmouthshire and has installed commercial solar and battery systems across South Wales, Mid Wales, Herefordshire, Gloucestershire, Worcestershire, Shropshire, the West Midlands and beyond. Whether you are a food producer in Pembrokeshire, a manufacturer in the West Midlands or a hotel group in the Wye Valley, our team can assess whether your existing solar system is ready for a BESS retrofit.
GET STARTED
Find out if your solar system is ready for a battery upgrade
Send us your site details and we will come back within 24 hours with a Quick Quote and initial financial model.