Battery Storage Installation

I install three battery systems: SigEnergy SigenStor, Fox ESS (EP and ECS series) and GoodWe Lynx Home. Not thirty. Three. I know every one of them inside out because I survey, design and install every system myself — and when something needs attention in year six, I'm the one who turns up, so I only fit kit I'd stand behind for the length of its warranty.

An honest note first: I used to fit GivEnergy. GivEnergy Ltd went into administration in April 2026, and no new warranties are being written, so I stopped. If you already own one, it keeps working — the monitoring app is run by a separate software company that's still trading, though some premium app features have moved to a paid subscription — and I'm happy to look after it under my maintenance service. But I won't sell you a battery whose warranty I can't stand behind.

Those price bands are what I'm actually quoting across Hampshire as of mid-2026, installed, including the electrical work and DNO paperwork — domestic battery installations are 0% VAT until 31 March 2027 (5% after that). Your exact price depends on capacity, whether you already have a compatible inverter, and cable runs, which is why I price from a survey rather than a postcode. There's a fuller cost breakdown in my battery storage cost guide, and a deeper head-to-head in my best solar battery comparison for 2026.

The right battery is decided by how your household uses electricity, not by whichever brand has the biggest marketing budget. When I survey a home in Hampshire, these are the patterns I'm matching against:

• Out all day, home in the evening. The classic case. Your solar generates while nobody's home, and you buy expensive electricity at 6pm. A mid-sized battery (8–10 kWh usable) captures the daytime surplus and covers the evening peak. Fox ESS EP11 or a two-module SigenStor is usually the sweet spot.
• EV owners. If you charge a car at home, you almost certainly should be on a time-of-use tariff — and once you are, the battery earns twice: it stores cheap overnight electricity for the day and soaks up solar surplus. EV households use more electricity overall, so I usually spec larger — 10–16 kWh usable — and make sure the battery, EV charger and tariff schedule don't fight each other. Getting those three working together is most of the value.
• Octopus time-of-use tariff users (Go, Intelligent Go, Cosy). As of mid-2026, the EV tariffs are the cheap ones: off-peak windows on Go and Intelligent Octopus Go sit roughly in the 5.5–9p/kWh range depending on tariff and region — Intelligent Go's off-peak rate dropped to around 5.5p in most regions from April 2026 — against a standard rate of around 26p under the July 2026 price cap. Cosy, aimed at heat-pump homes, offers three daily cheap windows at roughly 13–14.5p. A battery that charges in the cheap window and discharges through the day changes the economics of the whole house. SigenStor and Fox both schedule this well from the app; I set the charge windows up before I leave.
• Whole-home backup matters to you. If you work from home, run medical equipment, or are on a rural stretch of the SSEN network that drops out in storms, SigenStor with the Sigen Gateway is the one I fit — it can back up the whole house rather than a couple of nominated circuits.
• Tight budget, want to start small. The Fox ECS stack is the honest budget answer: start at ~5.8 kWh and add 2.88 or 4.03 kWh modules later as funds allow.
• Already have a GoodWe inverter. The Lynx Home battery drops onto it without replacing electronics that already work — often the cheapest total job of all.

At the survey I'll ask for your annual kWh usage, roughly how it splits day versus evening, whether an EV or heat pump is on the horizon, and what tariff you're on. Ten minutes with a recent bill tells me more than any online calculator. That's the benefit of the person quoting being the person installing — you can see what previous customers say about how that works out.

Roughly half my battery work in Hampshire is retrofit — adding storage to solar panels that are already on the roof, often systems installed a decade ago under the old Feed-in Tariff. The two routes differ, and it's worth knowing which you're in before you compare quotes:

• Retrofit (AC-coupled). Your existing panels and inverter stay exactly as they are; the battery gets its own inverter and connects on the AC side. Nothing about your existing array is touched, which matters if you're on a Feed-in Tariff — in almost all cases your FiT payments carry on unaffected, and I check your specific setup before we commit. The trade-off: that separate battery inverter typically adds £800–£1,200 of hardware, so retrofit usually works out around 15–25% more per kWh of storage than installing battery and solar together. No scaffolding needed — it's a day's work at ground level.
• Retrofit (hybrid swap). If your existing inverter is near the end of its life anyway — most last 10–12 years — it can make sense to replace it with a hybrid inverter and connect the battery on the DC side. Slightly bigger job, but you end up with one modern unit instead of two boxes, and it's often the better value if a replacement was coming regardless.
• New combined install. Battery and solar panels installed together on one hybrid inverter is the most efficient and the cheapest per kWh — one visit, one set of electrical work, one commissioning. If you're starting from scratch, my solar and battery package is the route I'd point you at.

Not sure which camp you're in? I've written a plain-English walkthrough in my guide to adding a battery to existing solar, or send me your setup and I'll tell you straight — including if the honest answer is that a battery doesn't stack up for your usage. It happens, and I'd rather say so than sell you one.

These are the questions that come up on nearly every survey from Southampton to Portsmouth and everywhere in between.

How quickly does a battery pay for itself on a time-of-use tariff?

Faster than on a standard tariff, because you're not just storing solar — on an EV tariff like Intelligent Octopus Go you're buying electricity at roughly 5.5–9p/kWh overnight (mid-2026 rates, region-dependent) and avoiding around 26p during the day at July 2026 price-cap rates. A well-sized battery cycled daily like this typically pays back in around 5–8 years against a 10-year warranty, with solar self-consumption on top. It depends on your usage and tariff, so I'll model it with your actual figures at the survey rather than promise a number here.

How long do these batteries actually last?

All three systems I fit use lithium iron phosphate (LFP) cells, rated for thousands of full charge cycles — from 4,000+ on the Fox EP series to around 6,000 or more on SigenStor — which is over a decade of daily cycling. The warranties run 10 years with guaranteed retained capacity, and the battery doesn't stop at the warranty line; it just holds a bit less than it did new. Realistically you should plan around a 10–15+ year working life.

Where does the battery go — can it be installed outside?

All three systems are weatherproof-rated for outdoor wall or ground mounting, and garages, utility rooms and external walls are the usual homes. Current British safety guidance (PAS 63100:2024) advises against installing batteries in lofts or on escape routes, and I follow it — if the only viable spot in your home is one I wouldn't put my own battery in, I'll tell you at the survey, not after.

Do I need permission from the electricity network?

Sometimes, and it's my job not yours. Systems up to 3.68 kW per phase go through as a G98 notification after commissioning. Anything larger — which includes most serious battery installs — needs G99 approval from SSEN, our local network operator, before the system is energised. I prepare and submit the application as part of every job; approval typically takes a few weeks, so it's the first thing I start once you go ahead.

Can I start small and add more capacity later?

Yes — this is one of the reasons I chose these three brands. SigenStor stacks additional ~8 kWh modules, Fox ECS adds 2.88 or 4.03 kWh modules to the stack, and GoodWe Lynx towers extend module by module. The practical caveat: batteries are best expanded with matching modules from the same product generation, so if you think you'll grow the system — say an EV is coming in two years — tell me at the survey and I'll spec the inverter and location with that headroom built in.

How quickly does a battery pay for itself on a time-of-use tariff?

How long do home storage batteries last?

Can a storage battery be installed outside?

Do I need permission from the electricity network to install a battery in Hampshire?

Can I start with a small battery and add more capacity later?