EcoFlow vs Thunder Energy: Which Plug-In Solar System Is Right for UK Homes?
Updated: Aug 19
Last updated 19.08.2026. Prices, product ranges and regulations checked on the date of writing.
Plug-in solar stops being a legal grey area in Britain on 27 August 2026. From that date, a certified device rated at 800VA or less can be connected through an ordinary 13A socket in England, Wales and Scotland, under SI 2026/848 and the government's Plug-in Solar Device Interim Product Specification.
That has turned a slow-burning question into an urgent one. Which system should you actually buy?
Two names come up more than any others. EcoFlow, the global portable power brand, and Thunder Energy, a UK solar company that was designing and installing compact systems on balconies, walls and garden structures before plug-in solar was on the table at all.
Both ranges have changed significantly since we first published this comparison. This is the updated version, and it covers two things most buying guides have not caught up with yet: which products actually qualify for the socket route, and where the new planning rules say you can put them.
The short answer
If your mounting surface is a balcony railing, a masonry or rendered wall, or a façade where weight is the constraint, Thunder's Storm range is built around 3.5 kg flexible panels and EcoFlow's is not.
If your panels are going on the ground, a flat roof, a garage or an outbuilding at a proper tilt angle, rigid panels win on output, and Thunder's Bolt range competes directly with EcoFlow while shipping as a complete kit.
If you want battery storage, read the next section closely. It is the single biggest change of July 2026 and it changes which EcoFlow products are even in the running.
Everything is in one place on the Thunder shop.
The rule that decides everything: the plug-in route has no batteries in it
This is the part most coverage still gets wrong, and it matters more than any spec sheet comparison.
The Interim Product Specification that takes effect on 27 August 2026 defines a plug-in solar device as solar panels plus a grid-following microinverter. Devices designed to store imported electricity are excluded from the socket-connection route. A battery-integrated unit cannot use a plug, however good its European credentials.
Look at what that means for each range.
EcoFlow's UK line-up is built around battery-integrated units. The STREAM Pro, STREAM Ultra, STREAM Ultra X and STREAM AC Pro all combine storage and inversion inside one enclosure. These are capable products, but they sit outside the plug-in route by definition and require a hardwired connection by a qualified electrician. Only the standalone STREAM Microinverter has the right architecture for the socket route.
Thunder's kits were designed the other way round. Storm and Bolt are panels plus a Hoymiles microinverter plus a fused UK AC connection cable, and nothing else in the signal path. When Thunder customers want storage, the Vault 1.92 kWh battery is a separate AC-coupled unit, so the solar side of the system keeps the shape the specification describes.
That is an architectural difference, not a marketing one, and it is why the two ranges are heading into 27 August in very different positions.
The new planning rules: where you can and cannot mount plug-in solar
A second piece of legislation lands on the same day and almost nobody is talking about it.
SI 2026/896, the Town and Country Planning (General Permitted Development) (England) (Amendment) Order 2026, rewrites Classes A and B of Part 14 from 27 August 2026. The good news is that plug-in solar is now explicitly defined as solar PV and picks up the same permitted development rights as any other panel. You do not need to ask your council.
The catch is a new restriction aimed specifically at plug-in solar, and it will catch a lot of people out.
You cannot fix plug-in solar to timber. Not to a wooden wall, balcony or enclosure. Not to any part of the outside of a house or block of flats that is clad in timber. And under Class B, not to a wooden fence, gate, wall or other means of enclosure. The reasoning is fire performance, and the Interim Product Specification takes a similar line on timber cladding and timber balconies.
In plain terms: from 27 August 2026, mounting a plug-in solar panel on a standard garden fence panel is no longer permitted development in England.
What is still fine:
Metal or glass balcony railings
Brick, block and rendered walls
Non-timber-clad building exteriors, within the projection limits
Ground-mounted and free-standing installations within the Class B height and area limits
Flat and pitched roofs, within the existing limits
Two important qualifications. This is an England-only planning change, and Scotland, Wales and Northern Ireland have their own regimes. And there is a transitional provision: anything that was permitted development immediately before 27 August 2026 and is no longer permitted afterwards can still be carried out up to the end of 26 August 2027.
If your plan was a fence, this is the point at which a Bolt kit on a ground frame or a Storm kit on a masonry wall becomes the better answer. If you are unsure which applies to your property, ask us before you buy.
The two ranges in 2026
Thunder Energy
Thunder now sells two families of kit, because UK homes have two very different mounting problems.
Storm, the flexible range. Built around 178W flexible TOPCon panels weighing 3.5 kg each, TÜV certified and tested to IEC 61215 and IEC 61730, IP67 rated with a Class C fire rating.
Storm 360W, two panels, 0.36 kWp, 7 kg of panels in total. £499.99
Storm 710W, four panels, 0.71 kWp, 14 kg of panels in total. £699.99
Modelled Year 1 generation for the Storm 710W is 525 kWh in London at a 90 degree vertical mount, which is the conservative case for a railing or wall. That is roughly £131 a year at 25p per kWh, with a payback around five years.
Bolt, the rigid range. Built around high-output rigid N-type TOPCon panels for gardens, flat roofs, garages and outbuildings where you can set a proper tilt angle.
Modelled Year 1 generation for the Bolt 900W is 1,013 kWh in London at a 40 degree tilt facing near due south, which is around £193 a year at 26p per kWh and a payback nearer four years.
Every Storm and Bolt kit uses the Hoymiles HMS-800-2WB microinverter: 800VA rated AC output, two independent MPPTs with a 16 to 60V tracking range and 65V maximum input, 96.7% peak efficiency, 99.8% MPPT efficiency, IP67 rated, fanless natural convection cooling, and 2.4 GHz Wi-Fi plus Bluetooth for S-Miles Home monitoring. The microinverter carries a 12-year warranty.
Storage. The Vault is a 1.92 kWh AC-coupled LiFePO4 battery at £1,049.99, IP66 rated, 6,000+ cycle life, ten-year warranty. It is also available bundled at £50 off:
Storm Plus 360W, £1,499.99
Bolt Plus 400W, £1,549.99
Storm Plus 710W, £1,699.99
Bolt Plus 900W, £1,749.99
EcoFlow
EcoFlow's STREAM family is broader and more modular, and it is worth understanding which product does what.
STREAM Microinverter, around £149 standalone. 800VA output, dual MPPT, ten-year warranty. Solar only, no storage. This is the product in the range with the right architecture for the UK socket route.
STREAM 800W kit, around £499 to £549 depending on retailer. The microinverter plus two 400W rigid glass panels at 21.8 kg each. Cabling, connectors and mounting brackets are typically sold separately.
STREAM Pro, around £799. 1.92 kWh battery integrated.
STREAM Ultra, around £999. 1.92 kWh battery, four MPPT inputs.
STREAM Ultra X, around £1,249. 3.84 kWh battery, four MPPT inputs.
STREAM AC Pro, around £699. Storage only, no solar inputs.
STREAM 5000, unveiled 23 June 2026. A 5 kWh, 5,000W home energy system that needs an electrician and sits well outside the 800W plug-in category.
EcoFlow prices move frequently and vary by retailer, so check before you buy.
Generation figures: read the small print on both sides
EcoFlow's UK marketing quotes up to 858 kWh a year and up to £115 of annual savings for the STREAM solar system. Read the footnote and that figure is modelled on the average German household consuming 3,113 kWh a year at £0.33 per kWh. It is not a UK figure, it does not reflect the UK price cap, and it assumes a favourable tilt.
We are not making that point to score off a competitor. We are making it because it is the most common way buyers end up disappointed.
Thunder publishes its modelling assumptions in full on every product page: PVGIS irradiance data for London, the tilt angle and azimuth used, a 3% allowance for soiling and real-world inverter efficiency, a clipping allowance where the panel array is larger than the 800VA inverter can pass, panel degradation rates, seasonal generation split, self-consumption rate and the tariff applied. The Storm figures assume vertical mounting. The Bolt figures assume a 40 degree tilt, because a ground or wall frame allows that angle to be set.
Two consequences follow.
Comparing headline wattages is close to useless. A 0.93 kWp Bolt 900W at 40 degrees generates roughly twice what a 0.71 kWp Storm 710W generates flat against a north-facing wall. Orientation beats wattage every time.
Ask any brand what tilt and what household their number assumes. If the answer is a laboratory angle or a continental European household, adjust your expectations downwards before you buy rather than afterwards.
Rigid or flexible: a structural question, not a preference
An EcoFlow 400W rigid panel weighs 21.8 kg. Two of them, plus brackets, puts well over 45 kg of static load on whatever you are fixing to.
Many UK balcony railings are designed for leaning on, not for load bearing. If your mounting surface is a railing, a rendered wall or a lightweight structure, a 21.8 kg panel is often simply not an option, and no amount of bracket engineering changes that.
That is why the Storm range exists. Four Storm panels weigh 14 kg in total, less than a single EcoFlow panel. It opens up surfaces that rigid panels close off.
The trade-off is real and worth stating plainly. Rigid glass panels are more efficient per square metre and generate more per kWp installed. If you have ground space, a flat roof, a garage or an outbuilding, rigid is the better technology, and that is exactly what Bolt 400W and Bolt 900W are for.
The difference between the two brands is not that one uses rigid and the other flexible. It is that Thunder sells both and matches the panel to your surface, while EcoFlow sells one shape and leaves the mounting problem with you.
Complete kit or shopping list
The Interim Product Specification certifies a complete product. Panel, inverter, factory-fitted cable, moulded BS 1363 plug with a fuse rated no higher than 5A, and the mounting system. Not an inverter plus panels plus brackets sourced separately from three suppliers, and not an extension lead.
This is where the two purchasing experiences diverge sharply.
A Thunder kit arrives with the panels, the Hoymiles HMS-800-2WB microinverter, the DC connection cables, the disconnect tools, the mounting hardware and a single-piece fused UK 3-pin AC cable, 5m as standard with a 10m option that replaces it rather than extending it.
An EcoFlow kit at kit level does not include cabling, connectors or mounting brackets on most listings. Those are sourced separately, which is fine if you know what you are doing and a real problem if you do not, because the assembled result is a collection of components rather than a certifiable product.
A UK solar company or a global electronics brand
EcoFlow is a large, capable manufacturer with real engineering behind it, a genuinely excellent app, and stronger retail distribution than anyone else in this market.
What EcoFlow does not have is anyone in the UK who will come to your house.
Thunder Energy Services Ltd is registered in England and Wales, VAT registered, and based at Belle House in London. The company came out of professional solar work: rooftop residential and commercial installation, PVsol-based system design, and SAP and EPC compliance support for developers. That background is why the kits ship with UK connection components rather than continental ones, and why G98 notification guidance comes with every system rather than being left for you to work out.
For customers in Greater London, professional installation is available at £399 on top of any kit, covering site assessment, panel mounting, electrical connection and G98 DNO notification as a complete service. Outside London, Thunder ships UK-wide with free delivery, a free setup video call, and support with finding a local electrician and completing the DNO notification.
This also matters if you rent. Thunder's Storm panels weigh 3.5 kg each, so the whole Storm 710W array is 14 kg and can be unclipped and taken with you when you move. A pair of EcoFlow rigid panels is 43.6 kg and a considerably bigger job to remove and transport.
Storage: two different philosophies
EcoFlow's approach is integration. Battery, inverter and smart control in one enclosure, with an app that is the best in this category. If you want a single device that does everything and you are prepared for a hardwired install, the STREAM Ultra is a strong product.
Thunder's approach is separation. Solar stays solar, storage is a separate AC-coupled unit. What it buys you is that the solar half of your system keeps the architecture the UK specification recognises, and you can add or remove storage without touching it.
If you are on a smart time-of-use tariff, the Vault also earns independently of the sun, by charging at overnight rates and discharging during peak hours. On our modelling a Storm Plus 710W delivers around £298 in Year 1 against £131 for the solar kit alone, with roughly half of that coming from tariff arbitrage rather than generation. Those figures assume a smart tariff with a genuine off-peak rate, and the full assumptions are published on the product page.
Which one should you buy?
Buy a Thunder Storm 360W or Storm 710W if your mounting surface is a metal balcony railing, a masonry or rendered wall or a façade that cannot take 22 kg per panel. If you rent and need something you can unclip and take with you. If you want a complete kit with the UK connection components already in the box.
Buy a Thunder Bolt 400W or Bolt 900W if you have garden space, a flat roof, a garage or an outbuilding and can set a proper tilt angle. Bolt 400W is the easiest single-panel entry point with room to expand. Bolt 900W is the highest-generating kit we sell and the fastest to pay back.
Buy a Plus bundle if you are on a smart tariff and want the arbitrage as well as the solar.
Buy EcoFlow if you are already inside their ecosystem with a DELTA power station, if app experience is what you care most about, or if you want a large integrated battery system and are comfortable arranging and paying for a hardwired installation yourself. The STREAM Ultra and Ultra X are good products. They are just not plug-in solar products under the UK rules.
Frequently asked questions
Is EcoFlow STREAM available in the UK?
Yes. EcoFlow sells the STREAM range in the UK, with the standalone microinverter from around £149 and an 800W kit with two 400W rigid panels from around £499 to £549 depending on retailer. Availability is not the same as certification, though. As of the date of writing, no EcoFlow product is verified on the ENA G98 Type Test Register against the Interim Product Specification.
Can I install EcoFlow without an electrician in the UK?
Only once a specific product has been certified against the Interim Product Specification and registered. EcoFlow's own UK documentation states that the STREAM DIY cable must be wired into the distribution board by a certified installer or electrician. Two further points are worth knowing. The battery-integrated units, the STREAM Pro, Ultra, Ultra X and AC Pro, are excluded from the socket route entirely, because the specification covers panels and a grid-following microinverter only. And the specification certifies a complete product, so an inverter plus panels plus brackets you sourced separately is not a certifiable kit however good the components are.
Can EcoFlow panels go on a garden fence?
Two separate reasons say no, and the second one now applies to every brand.
Structurally, each EcoFlow 400W rigid panel weighs 21.8 kg, and standard UK timber fence panels are not built for that load. Thunder's Storm panels weigh 3.5 kg each, which is what has historically made railing and wall mounting practical.
Legally, from 27 August 2026 in England, SI 2026/896 excludes plug-in solar fixed to a wooden fence, gate, wall or other means of enclosure from permitted development, along with wooden walls, balconies and timber-clad building exteriors. Metal railings, masonry walls and ground-mounted installations are unaffected. There is a transitional provision covering work permitted before that date up to 26 August 2027, and Scotland, Wales and Northern Ireland have separate planning regimes. If you had a fence in mind, a ground-frame Bolt is usually the better route.
Does Thunder offer installation outside London?
Professional installation is currently offered across Greater London at a fixed £399. Outside London, Thunder ships kits UK-wide with free delivery, a free setup video call, and support with finding a qualified local electrician and completing the G98 DNO notification.
Which system is better for renters?
Thunder, on weight alone. A Storm 710W array is 14 kg across four panels and can be unclipped and taken with you when you move. A pair of EcoFlow rigid panels is 43.6 kg. Under the Renters' Rights Act 2025, landlords cannot unreasonably refuse a request for a portable energy-efficiency improvement, though you should still give written notice, and freeholder or building management permission is a separate matter in flats.
Which EcoFlow products can be plugged into a socket in the UK?
Only a solar-only configuration can use the socket route at all, which in EcoFlow's range means the STREAM Microinverter with panels. The battery-integrated units, the STREAM Pro, Ultra, Ultra X and AC Pro, are excluded from the plug-in route by the Interim Product Specification and require a hardwired connection by a qualified electrician.
Whose generation figures should I believe?
Whichever ones tell you their assumptions. EcoFlow's 858 kWh headline is modelled on German household consumption at £0.33 per kWh. Thunder publishes PVGIS-based modelling for London with the tilt angle, degradation rate, soiling allowance, clipping allowance, self-consumption rate and tariff stated in full on every product page. Better still, run your own postcode through the savings calculator on any Thunder product page rather than relying on either brand's headline.
Which microinverter do Thunder kits use?
Every Storm and Bolt kit uses the Hoymiles HMS-800-2WB. It has an 800VA rated AC output, two independent MPPTs, a 16 to 60V MPPT tracking range, 96.7% peak efficiency and 99.8% MPPT efficiency, an IP67 enclosure with fanless natural convection cooling, and built-in Wi-Fi and Bluetooth for S-Miles Home monitoring. It carries a 12-year warranty against EcoFlow's 10 years on the STREAM Microinverter.
Do I still need to notify my DNO after 27 August 2026?
Yes. G98 notification to your local Distribution Network Operator remains required for grid-connected generation, and it is free. Thunder supplies the post-installation form and a DNO lookup with every kit.
What happens to a system installed before 27 August 2026?
Nothing. A system connected on a fixed installation by a qualified electrician and notified under G98 remains fully compliant. If you later move to a socket connection, the panels and microinverter stay exactly as they are and only the connection changes. Our 2026 timeline sets out the full sequence of dates, and our law explainer goes through SI 2026/848 clause by clause.
Ready to choose? Compare the full range on the Thunder shop, or run your own postcode through the savings calculator on any Storm or Bolt product page. Free UK delivery, 14-day returns, and a free setup video call with every kit.
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