How to Price a Battery Storage System Installation
Battery storage is the fastest growing add-on in the UK solar market. As panel prices have fallen and energy prices have stayed high, the payback case for batteries has strengthened considerably. For solar installers, battery storage represents higher average job values, better margins, and a natural expansion of the product offering.
Pricing it correctly requires understanding the cost components, the technology options, and how to present the financial case to customers.
Why Battery Storage is Growing
- Energy prices: Higher retail electricity rates mean every kWh of self-consumed solar is more valuable
- Time-of-use tariffs: Tariffs like Octopus Agile allow batteries to be charged cheaply overnight and discharged during peak periods – independent of solar
- SEG rates: As export rates are relatively low, maximising self-consumption (via battery) is financially better than exporting
- Grid resilience: Power outages have raised interest in backup power capability
The result: most solar customers are now either installing batteries at the same time or enquiring about retrofit battery installation within 12-24 months.
Battery Storage Technology Overview
The main battery technologies in the UK residential market:
| Brand/Technology | Capacity options | Typical installed cost |
|---|---|---|
| GivEnergy | 2.6-17kWh | £2,500-£6,000 |
| Tesla Powerwall 3 | 13.5kWh | £8,000-£10,000 installed |
| SolarEdge Home Battery | 9.7-48kWh | £3,000-£8,000 |
| Growatt | 2.56-15.36kWh | £2,000-£5,000 |
| Solis | Various | £2,000-£5,000 |
| Sunsynk | 5-20kWh | £2,500-£6,000 |
Technology types:
– AC-coupled: connects to the existing AC side of the electrical system. Works with any existing solar inverter. More flexible for retrofits.
– DC-coupled: connects directly to the solar array. More efficient for new installations. Typically requires a hybrid inverter.
For retrofitting batteries to existing solar systems, AC-coupled is almost always the right choice. For new installs, a hybrid inverter with DC-coupled battery is often more efficient and cost-effective.
Cost Components for Battery Installation
New installation (solar + battery)
When installed alongside new solar PV, battery installation costs are lower because:
– Electrical work is combined
– Scaffolding is already erected
– Commissioning is done together
Additional cost above solar-only: £800-£1,500 in labour plus the battery hardware.
Retrofit installation
Retrofitting a battery to an existing solar system is a standalone job:
| Component | Typical cost |
|---|---|
| Battery unit (5-10kWh) | £800-£2,500 |
| Hybrid inverter (if required for DC coupling) | £500-£1,200 |
| AC coupling hardware (if AC coupled) | £100-£300 |
| Electrical installation (1 day, 1-2 people) | £300-£600 |
| Monitoring setup and commissioning | £100-£200 |
| Total cost (5kWh AC coupled) | £1,300-£3,800 |
Pricing and Margins
New install (solar + battery) uplift pricing:
A 4kWp solar + 5kWh battery versus solar only:
| Item | Solar only | Solar + battery |
|---|---|---|
| Equipment cost | £1,800 | £3,200 |
| Labour | £500 | £700 |
| Scaffold | £350 | £350 |
| Total cost | £2,650 | £4,250 |
| Customer price (30% margin) | £3,790 | £6,070 |
| Market price | £5,500-£7,000 | £8,000-£11,000 |
Battery retrofit pricing:
A standalone 10kWh battery retrofit:
– Cost: £2,500-£3,500
– Customer price at 30% margin: £3,570-£5,000
– Market price: £4,000-£6,500
Margins on battery storage are typically 25-40% – comparable to or better than solar-only installations.
VAT on Battery Storage
Important: The 0% VAT rate on energy-saving materials (including solar PV) extends to battery storage when installed at the same time as solar panels, or alongside an existing solar installation (from April 2022, under current rules).
Standalone battery storage installed on a property with no solar is standard rated at 20%.
Always check current HMRC guidance on VAT for energy-saving materials before quoting – VAT rules on this have changed before.
Presenting Battery Storage to Customers
Include a payback calculation in every battery quote:
Example (10kWh battery, 4kWp solar):
– Additional annual self-consumption from battery: ~1,500 kWh
– At £0.24/kWh electricity price: £360/year additional saving
– Additional cost of battery: £2,500
– Battery payback: ~7 years
Combined with the solar payback, the overall system payback is typically 8-12 years for a quality installation – with a 25-year system lifespan. That’s a compelling case.
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Frequently Asked Questions
What size battery do I need for a 4kWp solar system?
A 5-10kWh battery is appropriate for most homes with a 3-5kWp solar system. A 5kWh battery covers the evening usage of a typical household. A 10kWh battery provides more overnight cover. Match battery size to daily energy consumption patterns – a detailed load assessment produces the best recommendation.
Can I retrofit a battery to any existing solar installation?
Yes, in most cases. AC-coupled batteries connect to the AC side of the system and work with any existing inverter. The key checks are: available space for the battery unit, suitability of the electrical consumer unit, and whether the existing solar inverter needs updating.
Is battery storage covered by MCS certification?
Yes – if you want to install and certify battery storage under MCS, you need the C&G 2919 qualification and MCS certification for the battery storage technology category. See mcscertified.com for product and installer certification requirements.
What is vehicle-to-grid (V2G) and is it relevant for battery installers?
V2G technology allows electric vehicles to discharge stored energy back to the home or grid. It’s an emerging technology in the UK (2026) with limited compatible vehicles and chargers. Worth monitoring but not yet mainstream. V2G-compatible installations require specific charger hardware and grid connection arrangements.
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