GoodWe vs SigEnergy: Which Battery Should You Fit in 2026?

Both systems use lithium iron phosphate (LFP) cells — the safer, longer-cycle chemistry for home storage — and both are hybrid, DC-coupled systems that run your panels and your battery through one piece of electronics. The real difference is architectural. GoodWe splits the job across a wall-mounted hybrid inverter and a separate battery tower. SigEnergy's SigenStor puts the inverter, battery management, storage modules, energy management and (optionally) an EV charger into a single stack. Here is how they line up in 2026.

One naming trap worth knowing: SigEnergy's module names round up. A "BAT 10.0" is 9.04 kWh nominal and 8.76 kWh usable, not 10 kWh. GoodWe's Lynx Home F is the opposite — the datasheet's usable energy figure sits at essentially the full nominal capacity, so a five-module tower really does give you 16.38 kWh to play with.

On paper they are closer than the marketing suggests. Both will store a day's south-coast generation, both do sub-second changeover to backup, both are covered for a decade. Where they diverge is cost per usable kWh, what you can bolt onto them later, and how much wall you have to give up — which is what the rest of this page is about. If you want the wider field including Fox ESS and Tesla, start with our best solar battery 2026 comparison.

Domestic battery storage — retrofitted or fitted alongside solar — carries 0% VAT until 31 March 2027, after which it is scheduled to revert to 5%. The zero rate applies to installation in residential accommodation by a VAT-registered installer, and has covered standalone retrofit batteries (no solar required) since 1 February 2024. On a £6,000 system that deadline is worth roughly £300, so pricing is as good now as it is going to be. Commercial installations are charged at 20%, recoverable if the business is VAT-registered.

These are indicative installed bands for a typical Hampshire retrofit in 2026 — real fitted prices including labour, isolators, commissioning and the grid application, not trade-counter hardware costs. They are guide figures only; your survey price will differ with cable runs, board condition and siting.

Note the shape of it. At small sizes GoodWe is clearly cheaper per usable kWh, because you are buying modest electronics and a couple of inexpensive modules. As you scale up, SigenStor narrows the gap to roughly level — at the top of each range the two are within about £25/kWh of each other — because you are adding bare battery modules to a controller you have already paid for. What SigenStor does not do, on these bands, is undercut GoodWe outright. If lowest cost per stored kWh is the only metric, GoodWe wins at every size we commonly fit.

On payback, be realistic. Export income alone won't do it: widely available Smart Export Guarantee rates ran roughly 3p to 25p per kWh through 2026, the best of them tied to using the same supplier for your import electricity or to a specific installer, and suppliers can change them with notice — always check the current figure with your own supplier before you model anything. What actually pays for a battery here is tariff arbitrage: charging overnight on a cheap off-peak rate and discharging through the day. On that basis, and assuming a time-of-use import tariff and a battery sized to cycle fully most days, a well-sized retrofit on the Solent is typically modelled at a 6–9 year payback — shorter if you already have solar exporting for pennies, longer on a flat-rate tariff or an oversized bank. It is an estimate, not a promise, and we model it against your own consumption data at survey. Full costings sit on our battery storage service page.

Every job is surveyed and specified before anything is ordered, so the recommendation is the one we have to live with when we come back. Here is how it actually breaks down.

1. Small retrofit on an existing array — GoodWe

A 3–4 bed semi in Locks Heath or Hedge End with a 4 kWp array already on the roof, wanting to stop exporting for pennies. You need 6–10 kWh usable and nothing clever. GoodWe wins on price per kWh at this size, the EH PLUS+ hangs on a garage wall in an afternoon, and the free PLUS+ extension takes the inverter warranty to 10 years at no extra cost. Adding a SigenStor here means paying for an energy controller and an ecosystem you'll never fully use. Details on the range are on our GoodWe brand page.

2. Whole-home backup or a bigger property — SigenStor

Larger detached houses in the Meon Valley, Bishop's Waltham or out toward Hambledon, where the supply is rural, outages are a genuine annoyance and there's a home office to protect. GoodWe's backup covers selected circuits at 3,600–6,000 VA — fine for a fridge, boiler, router and a few sockets. The SigenStor with a Sigen Gateway is designed to carry the whole property: the HomePro variant is rated at 100 A / 22 kW, enough for a full single-phase domestic service without splitting out a backup sub-board, and the Smart Port lets the system shed a high-draw load like an immersion heater rather than dropping the freezer. If backup is the reason you're buying, that difference is the whole decision.

3. EV household, or one that will be — SigenStor

This is the clearest case. The SigenStor's 12 kW DC charging module charges the car directly from DC solar and battery power, skipping the DC→AC→DC double conversion you get with a separate AC chargepoint. One stack, one app, one warranty conversation. The hardware is also bidirectional and V2X-ready, though that is capability in waiting — it depends on your vehicle and on UK standards catching up, so don't buy on it today. If you already have a Zappi or an Ohme you're happy with, the advantage shrinks and GoodWe plus your existing charger is the sensible spend. See the SigEnergy brand page for the full stack options.

Where we'd steer you away from both: if the budget is fixed and tight and you simply want maximum stored kWh for the money, look at our Fox ESS vs GoodWe comparison before you decide — Fox is the volume brand for a reason.

Four practical differences that never appear in a brochure but shape how the system feels to own.

Commissioning and warranty admin. GoodWe's 10-year inverter warranty is not automatic. It requires a qualified PLUS+ installer, serial numbers registered on the SEMS warranty portal, an inverter manufactured after 1 January 2021, and the system connected and successfully uploading data to the SEMS+ app. That last part matters: if a homeowner changes broadband or moves the router and the inverter drops off the network, the monitoring stops. Worth knowing too: the extension is tied to a named list of compatible GoodWe batteries and to first operation between 15 May 2023 and 31 December 2026, so we check the current eligible-product list at the time of your install rather than assuming. We register every system before we leave and check the upload. The SigenStor commissions through the mySigen app and has connectivity built in, so there's less to go wrong later.

Firmware pace. SigEnergy ships over-the-air updates frequently, adding tariff logic and V2X-related features. That is a genuine advantage if you like the system improving, and a mild irritation if you'd rather it never changed. GoodWe moves slowly and predictably. For a customer who wants set-and-forget, slow is a feature.

Who's still there in year seven. GoodWe has a UK office in Letchworth Garden City with its own UK sales and service contacts; SigEnergy is a much newer arrival to the UK market and support runs through the installer and distributor channel. Neither of those is a service guarantee and we won't pretend to know anyone's turnaround times in advance. But brand continuity is genuinely part of the specification decision right now: GivEnergy Ltd entered administration on 9 April 2026, ceasing to trade, with administrators appointed through the High Court in Leeds. Choosing hardware is partly choosing who will still be answering the phone in year seven.

Footprint, and single unit versus split. The SigenStor is one floor-standing stack, 700 mm wide and 260 mm deep, growing from about 370 mm to just under 2 m tall as you add modules — wall mounting is limited to the smaller configurations, and larger stacks are floor-standing. It needs a clear 700 mm of floor. GoodWe splits into a wall-hung inverter plus a separate battery tower, which is more flexible in awkward spaces but consumes more total wall once you add isolators and the backup switching. In a narrow Southsea utility cupboard that split usually wins. In a Whiteley integral garage, the single stack looks tidier and is faster to fit.

One more: adding capacity later. Both are modular, but on GoodWe extra modules don't buy extra power — you're still capped at the inverter's 25 A, which is up to 6 kW charging and 5–6 kW discharging depending on model. On the SigenStor, spec the Energy Controller for where you're heading, not where you are, or you'll be replacing electronics to unlock the capacity you added.

Everything above is national. These are the local realities that change the answer in Fareham, Portsmouth, Southampton and Winchester.

SSEN and the G98/G99 line. Our whole patch sits in SSEN's Southern licence area — Southern Electric Power Distribution covers Hampshire including Southampton, Portsmouth, Winchester and the Isle of Wight — so every grid application goes to them and we handle it. The threshold is simple: G98 covers up to 3.68 kW per phase (11.04 kW across three phases) and is a notification submitted within 28 days of commissioning; G99 is a full application that must be approved before the system goes in. A 5 kW or 6 kW GoodWe EH PLUS+ and any SigenStor Energy Controller above 3.68 kW both fall into G99 territory, so the paperwork and SSEN's response time need to be in the plan from day one — not discovered after you've paid a deposit. Where SSEN restrict export, both systems can be export-limited to an agreed figure without losing the ability to charge the battery.

Single-phase is the norm here. Domestic three-phase supplies are rare across Fareham, Havant and Winchester housing stock, which quietly rules out GoodWe's ET PLUS+ series for most homes — the ET PLUS+ is a three-phase inverter. The realistic domestic GoodWe fit is the single-phase EH PLUS+ or ES G2. ET comes into its own on the light-industrial units around Segensworth and Solent Business Park.

Salt air is a real siting constraint. Around Hamble-le-Rice, Warsash, Lee-on-the-Solent, Gosport seafront and Hayling Island, the SigenStor's IP66 rating means it can genuinely live outside. The Lynx F G2 battery is IP55 — rated for indoor or sheltered external installation — and the GoodWe inverter is IP65. Perfectly good ratings, but on an exposed coastal elevation we'll put GoodWe in a garage or utility every time. That's not a criticism of the kit; it's what the ratings are for.

Housing stock decides the footprint. The 1990s-onward estates at Whiteley, Park Gate and Locks Heath usually have an integral garage and a 100 A single-phase supply — ideal for a floor-standing SigenStor. Victorian terraces in Southsea, Portswood and central Eastleigh often have no garage at all, and a wall-hung GoodWe split is the only thing that physically fits. In the conservation areas around Titchfield, Old Portsmouth and the Winchester City Council area, keeping everything internal also avoids arguments about external equipment.

Sizing to south-coast yield. We see roughly 950–1,050 kWh per kWp per year on Solent roofs, so a typical 4 kWp array generates around 3,800–4,200 kWh annually. That's why 8–10 kWh usable is the sweet spot for most households here — a 20 kWh bank sized for a Scottish winter simply won't cycle enough to earn its keep on a Fareham semi. Treat that as a starting point: on Ofgem’s typical figures a medium-use home needs closer to 5 kWh, which what size solar battery you need works through.

EV grants, briefly. The OZEV chargepoint grant rose from £350 to £500 per socket on 1 April 2026 and covers 75% of the combined chargepoint and installation cost up to that cap — but it is limited to flats, renters and residential landlords, so owner-occupiers with a private driveway are excluded. Landlords can claim up to 200 sockets a year. The separate Workplace Charging Scheme also pays 75% up to £500 per socket, for up to 40 sockets and £20,000 per business. Both schemes are currently funded to 31 March 2027. If you're relying on a grant, confirm the specific unit is on the OZEV-approved list before committing; integrated DC chargers built into a storage stack are not always listed, and we'd rather flag that at survey than after.

If you want storage that quietly saves money and nothing else, GoodWe. It's cheaper per usable kWh at every size most Solent homes actually need, the PLUS+ programme gets you a 10-year inverter warranty for free, and there's a UK office behind it. It is the right answer for the majority of straightforward retrofits.

If you drive an EV, need the whole house to stay up during an outage, or you're building toward vehicle-to-home, SigEnergy's SigenStor is worth the premium. The DC EV module and the Sigen Gateway do things GoodWe genuinely cannot, and at 17 kWh and above the cost-per-kWh gap narrows to roughly level — you stop paying a meaningful premium for the extra capability.

What we won't do is sell you the more expensive stack because it's more interesting. Every install here is surveyed and specified by Tom, owner-led from first visit to commissioning, so the system that goes in is the one we'd want to be responsible for in ten years' time. Book a free survey and we'll size both options against your actual consumption data and tell you plainly which one wins on your roof.

Is SigEnergy better than GoodWe?

Can I add a GoodWe or SigEnergy battery to solar panels I already have?

Does the SigenStor's built-in EV charger qualify for the OZEV grant?

Do I need SSEN's permission before installing a GoodWe or SigEnergy battery?

Will battery prices go up when the 0% VAT rate ends?