Most of the solar panels on UK roofs travel halfway around the world before they reach a scaffold. If you would rather know exactly where your system was built, who built it and under what standards, there is now a strong European alternative for both halves of a solar hot water setup: Eurener solar panels, manufactured in the EU in Spain, and Sunamp Thermino heat batteries, designed and built in Scotland.
This guide explains each product on its own, then shows how they work together: where they are made, what they are used for, how the Thermino ePlus and xPlus are connected, which model and Optimino key to choose for your situation, and which accessories you should not skip.
Generate it in Spain-built panels, store it in a Scottish heat battery, and use it as mains-pressure hot water in a cupboard-sized space.
Why European manufacturing matters
“Made in Europe” is more than a sticker. It shortens the supply chain, makes factory audits and material traceability far easier, and means the products are built under European labour, environmental and product-safety rules. For installers it also means a manufacturer that is close enough to talk to when something needs resolving.
Where these products are actually made
Eurener, Langreo (Asturias, Spain)
Eurener's module factory in Langreo was built in partnership with Iberdrola and Exiom, with an annual capacity of around 500 MW — roughly one million panels a year — aimed squarely at European rooftops.
Eurener, Bembibre (León, Spain)
An integrated site run with European Solar Cells that produces photovoltaic cells as well as modules, plus replacement panels and special architectural designs. Cell production in Europe is still rare.
Sustainability you can audit
Founded in 1997, Eurener holds an EcoVadis Platinum medal (top 1% of rated companies) and works to the ISO 14001 environmental management standard.
Sunamp, Macmerry (East Lothian, Scotland)
Thermino heat batteries are designed and manufactured in Scotland. Their Plentigrade P58 phase change material was developed with the University of Edinburgh, and Sunamp is a King's Award for Enterprise recipient.
A quick note on accuracy: Eurener panels are made inside the EU (Spain). Sunamp is made in the UK (Scotland), so it is European-made and British-made rather than EU-made.
Eurener solar panels explained
Eurener is a Spanish photovoltaic manufacturer that specialises in the European residential market. We stock three of its modules, covering two cell technologies.
Nexa series: N-type TOPCon bifacial
TOPCon (tunnel oxide passivated contact) cells cut recombination losses, which improves low-light output and slows degradation compared with older P-type PERC panels. N-type cells are also not prone to light-induced degradation (LID).
The dual-glass bifacial build lets the rear of each cell catch reflected light. On the Nexa 475W, Eurener quotes a bifaciality factor of 80% ± 5%, adding up to 10% extra yield (523 Wp) over bright surfaces.
Ultra series: back contact bifacial
Back contact cells move all of the electrical contacts to the rear of the cell, so there are no busbars shading the front. That gives a cleaner, uniformly black face and higher efficiency — 24.5% on the Ultra 500W.
Eurener positions the Ultra range for architectural integration: homes where the look of the roof matters as much as the output.
Where Eurener panels fit best
- Standard pitched residential roofs: the Nexa 475W's 1762 × 1134mm footprint suits typical UK roof sizes, and it carries MCS certification (BABT8916-228) for SEG eligibility.
- Flat roofs, carports and ground mounts: anywhere light can reach the rear glass — pale membranes, gravel, concrete — is where bifacial gain actually shows up.
- Premium new builds and conservation-sensitive homes: the all-black Ultra and all-black Nexa finishes blend into slate and dark tile roofs.
- Exposed or high-load sites: the Nexa 475W is rated to 5400 Pa front load and 2400 Pa rear, Class A fire rated and hail certified (RG3/HW3).
Pair the panels with a suitable hybrid inverter and mounting system, or browse our wider solar panels and solar bundles.
Eurener's own overview of the Nexa TOPCon range (420–700W). Watch on YouTube
Sunamp Thermino heat batteries explained
A Thermino replaces a traditional hot water cylinder. Instead of storing a tank of hot water, it stores heat in Plentigrade P58, a patented phase change material (PCM) that melts and solidifies at 58°C. Melting absorbs a large amount of energy in a small volume; when you run a tap, cold mains water passes through a heat exchanger inside the PCM and leaves hot, at mains pressure.
Heat goes in as the PCM melts, and comes out as the PCM solidifies around the water heat exchanger.
Space
Up to four times smaller than the cylinder it replaces. Every model shares a 365 × 575mm footprint — only the height changes — so it fits in kitchen units, under stairs and in service cupboards.
Heat loss
0.48–0.84 kWh per 24 hours across the range, against the 1.5–3+ kWh typical of an indirect cylinder. Less standing loss means more of what you generate or pay for ends up in the shower.
Compliance and upkeep
Sunamp states the unit holds under 15 litres of water, so G3 unvented certification is not required, and there is no mandatory annual service.
Longevity
The PCM is tested to over 40,000 charge cycles (50+ years) with no measurable degradation, backed by a 10-year warranty on the heating element and PCM core for UK installations.
Thermino ePlus: the direct electric heat battery
The ePlus is small enough to live in a standard kitchen unit.
The Thermino ePlus is charged directly by electricity through a built-in 2,800W element on a dedicated 16A circuit. It can charge from the grid on a cheap overnight tariff, from surplus solar via a diverter, or both. It comes in four sizes — 70, 150, 210 and 300 — with 40°C outputs of 105 to 436 litres.
Thermino xPlus: the indirect heat battery
The xPlus is charged by a heat pump or boiler through an internal heat exchanger.
The Thermino xPlus replaces an indirect cylinder. It is charged by an external heat source — a system boiler, a combi (in pre-heat mode), an air source or a ground source heat pump — with a built-in element as backup. Charged by a heat pump it achieves Energy Class A+, and it comes in 150, 210 and 300 sizes delivering 199 to 402 litres at 40°C. It also qualifies as ancillary equipment under the Boiler Upgrade Scheme when installed with a heat pump.
A real-world look: four years of Thermino hot water in a 1960s house. Watch on YouTube
Thermino vs a conventional unvented cylinder
| Feature | Sunamp Thermino | Typical unvented cylinder |
|---|---|---|
| Storage medium | Phase change material (Plentigrade P58) | Stored hot water |
| Relative size | Up to 4× smaller | Full-size tank |
| Standing heat loss | 0.48–0.84 kWh/24h | 1.5–3+ kWh/24h (indirect) |
| G3 unvented certification | Not required (under 15L of water, per Sunamp) | Required |
| Mandatory annual service | None | Annual G3 service |
| Hot water pressure | Mains pressure | Mains pressure |
| Change of heat source later | Swap the Optimino key | Often a new cylinder or coil |
How the ePlus and xPlus are connected
Both models share the same water side. The difference is how heat gets in. Your installer should always follow Sunamp's current installation manual; the steps below show the logic so you know what you are buying.
Thermino ePlus connection
Condition the cold feed
Mains cold water (minimum 1.5 bar) is fitted with a scale reducer such as the HydroFLOW Pearl where hardness is above 150 ppm. The Thermino is not suitable for tank-fed systems.
Fit the protection kit
The Sunamp A2057 kit provides the pressure reducing valve (3 bar recommended), expansion vessel and thermostatic mixing valve that protect the unit and your household.
Charge with electricity
The 2.8kW element runs on a dedicated 16A circuit, timed to off-peak hours. For solar, a diverter such as the myenergi eddi sends surplus PV to the battery, with the Optimino PV key configuring the unit for it.
Deliver safe hot water
Hot water leaves through the TMV, set to 45–55°C as UK Building Regulations require, and feeds your taps and showers at mains pressure.
Thermino xPlus connection
Same water side
Cold mains, scale reducer and the A2057 protection kit are fitted exactly as for the ePlus.
Connect the primary circuit
Flow and return from the heat pump or boiler go to the internal heat exchanger. Maximum flow temperature is 80°C, with charge flow rates of 15, 20 or 25 l/min depending on size.
Fit the right Optimino key
The key tells the heat battery how to talk to its heat source: vf for a boiler, hp for a heat pump, and vfPV or hpPV when solar is added.
Backup and boost
The built-in element charges from the grid if the primary source is off, and with a PV key it can soak up surplus solar too.
A step-by-step plumbing walkthrough for installers. Watch on YouTube
Which Thermino and which key for your home?
| Your situation | Model | Optimino key | Extras to add |
|---|---|---|---|
| Flat or home with no wet heating, on an off-peak tariff | ePlus | None needed to start | A2057 kit, scale reducer |
| Solar PV home replacing an immersion cylinder | ePlus | PV key | myenergi eddi, A2057 kit |
| New or planned air or ground source heat pump | xPlus | hp key (heat pump range) | A2057 kit, scale reducer |
| Heat pump plus solar PV | xPlus | hpPV key | Diverter, A2057 kit |
| Gas system boiler now, heat pump later | xPlus | vf key, swap to hp later | A2057 kit |
| System boiler plus solar PV | xPlus | vfPV (Boiler + PV key) | Diverter, A2057 kit |
| Combi boiler, want to cut gas use | xPlus (pre-heat) | vf key | A2057 kit |
| Tank-fed (gravity) hot water | Not suitable until the property is converted to a mains-pressure supply | ||
Choosing the size
70 (ePlus only)
105 litres at 40°C, 6 l/min. One-bedroom flats and single-occupancy homes.
150
199 litres at 40°C, 15 l/min. One- to two-bedroom homes.
210
301 litres at 40°C, 20 l/min. The usual pick for a three-bedroom home.
300
436 litres (ePlus) or 402 litres (xPlus) at 40°C, 25 l/min. Four bedrooms and up, or several showers at once.
Need more? Multiple units can be connected in series or parallel for higher-demand properties.
Putting them together: real-world applications
Solar-first hot water
Eurener panels on the roof, an eddi diverting surplus to a Thermino ePlus with a PV key. Summer hot water comes almost entirely from the sun; in winter the unit tops up overnight on an off-peak tariff.
Heat pump retrofit with no cylinder space
An xPlus with the hp key gives a heat pump somewhere to put its hot water without losing a whole airing cupboard. Add Eurener PV and the hpPV key later.
Staged move off gas
Fit an xPlus on the existing boiler with the vf key now. When the heat pump goes in, swap the key rather than the heat battery.
New builds, flats and rentals
A small footprint, no G3 certification and no mandatory annual service suit developers working toward the Future Homes Standard and landlords who want fewer call-outs.
Shop the range
Eurener
Nexa 475W TOPCon Bifacial Panel
All-black N-type TOPCon dual-glass module at 23.77% efficiency, sized for standard UK roofs. MCS certified with a 25-year product and 30-year performance warranty.
£153.00 inc. VAT
Buy Nexa 475W
Eurener
Nexa 515W TOPCon Bifacial Panel
Higher-output Nexa TOPCon bifacial module at 23.16% efficiency. A strong choice where you want more watts per panel on larger roofs or ground mounts.
£139.00 inc. VAT
Buy Nexa 515W
Eurener
Ultra 500W Back Contact Bifacial Panel
Back contact cells with no front busbars for a clean full-black look and 24.5% efficiency. Built for homes where roof appearance matters.
£179.00 inc. VAT
Buy Ultra 500W
Sunamp
Thermino ePlus Direct Heat Battery
Direct electric heat battery in 70, 150, 210 and 300 sizes. Charges from off-peak electricity and, with the PV key, surplus solar.
From £1,595.00 inc. VAT
Buy ePlus
Sunamp
Thermino xPlus Indirect Heat Battery
Indirect heat battery for heat pumps and boilers in 150, 210 and 300 sizes. Energy Class A+ with a heat pump and ready for a change of heat source via Optimino keys.
From £2,200.00 inc. VAT
Buy xPlusFull specifications
Eurener panels
| Model | Power | Efficiency | Cell technology | Bifacial | Price inc. VAT |
|---|---|---|---|---|---|
| Nexa 475W (MEPV475H-16YII) | 475 Wp (523 Wp with 10% rear gain) | 23.77% | N-type TOPCon, half-cut | Yes, dual glass | £153.00 |
| Nexa 515W | 515 Wp | 23.16% | N-type TOPCon | Yes | £139.00 |
| Ultra 500W | 500 Wp | 24.5% | Back contact | Yes | £179.00 |
Nexa 475W detail: 1762 × 1134 × 30mm, 24 kg, 1500V DC max system voltage, MC4-Evo 2 connectors, IP68 junction box, temperature coefficient of Pmax −0.29%/°C.
Thermino ePlus
| Model | Equiv. cylinder | V40 | Max flow | Heat loss /24h | Energy class | Filled weight | Height |
|---|---|---|---|---|---|---|---|
| 70 ePlus | 74 L | 105 L | 6 l/min | 0.48 kWh | C | 79 kg | 440mm |
| 150 ePlus | 140 L | 199 L | 15 l/min | 0.67 kWh | C | 140 kg | 640mm |
| 210 ePlus | 212 L | 301 L | 20 l/min | 0.77 kWh | C | 178 kg | 870mm |
| 300 ePlus | 306 L | 436 L | 25 l/min | 0.84 kWh | C | 233 kg | 1050mm |
Thermino xPlus
| Model | Equiv. cylinder | V40 | Max HW flow | Max charge flow | Heat loss /24h | Energy class | Filled weight | Height |
|---|---|---|---|---|---|---|---|---|
| 150 xPlus | 142 L | 199 L | 15 l/min | 15 l/min | 0.67 kWh | A+ | 136 kg | 640mm |
| 210 xPlus | 212 L | 301 L | 20 l/min | 20 l/min | 0.77 kWh | A+ | 187 kg | 870mm |
| 300 xPlus | 284 L | 402 L | 25 l/min | 25 l/min | 0.84 kWh | A+ | 233 kg | 1050mm |
All Thermino models: 365mm wide × 575mm deep, minimum supply pressure 1.5 bar, maximum working pressure 5 bar, TMV setting 45–55°C. The xPlus accepts a maximum heat source flow temperature of 80°C.
The accessories that make or break the install
A heat battery is only as reliable as the components around it. These four items protect the warranty, keep the unit safe and let it use your solar.
Sunamp A2057 Installation (Protection) Kit
Required on every installContains the pressure reducing valve, thermostatic mixing valve and expansion vessel for both ePlus and xPlus. The TMV is a Building Regulations requirement because the PCM stores heat hot enough to scald, and the PRV and vessel keep the unit within its pressure limits.
£223.00 inc. VAT
Buy Installation KitHydroFLOW Pearl Limescale Reducer (HS38)
Hard water areasWhere mains hardness exceeds 150 ppm, Sunamp requires a scale-reducing device on the cold feed, and the Pearl is the accessory Sunamp recommends. It clips around pipework up to 38mm with no cutting, and scale in the heat exchanger is the fastest way to lose performance — and your warranty.
View DetailsSunamp Optimino Keys for Heat Pumps
xPlus with a heat pumpThe hp key links the xPlus to your heat pump's controls so it charges the battery efficiently. Choose the version matched to your heat pump brand. Adding solar? Go for the hpPV configuration.
From £123.00 inc. VAT
Buy HP Keysmyenergi eddi 2.1 Energy Diverter
Solar diversionThe eddi detects when your panels are exporting and diverts that surplus into the heat battery instead of selling it to the grid for pennies. It is a compatible diverter for Thermino's PV configuration and adds Wi-Fi monitoring.
View DetailsAlso useful: the Optimino PV Key (£95.00) for solar on the ePlus, and the Optimino xPlus Boiler + PV Key (£143.00) for boiler-plus-solar systems. Browse our solar immersion controllers for other diverter options.
Before you order: Thermino units are heavy — up to 233 kg filled for the 300 models. If access involves stairs, ask us about stair-climber delivery when you order.
Certifications and credentials
Frequently asked questions
Are Eurener panels really made in the EU?
Yes. Eurener manufactures its modules at two factories in Spain: Langreo in Asturias and an integrated cell and module plant in Bembibre, León.
Is Sunamp made in the EU?
Sunamp is made in Scotland, so it is UK-made rather than EU-made. Combined with Eurener panels, the whole system is European-built.
What is the difference between the ePlus and the xPlus?
The ePlus is heated directly by electricity from the grid or solar. The xPlus is heated by a boiler or heat pump through an internal heat exchanger, with an electric element as backup.
Can I add solar to a Thermino later?
Yes. Fit the relevant Optimino PV key and a diverter such as the myenergi eddi. You do not need a new heat battery.
Do I need a scale reducer?
If your water hardness is above 150 ppm, Sunamp requires one on the cold feed. Most of south and east England falls into this category, which is why we recommend the HydroFLOW Pearl.
Does the Thermino work with the Boiler Upgrade Scheme?
When installed with a heat pump, the xPlus qualifies as ancillary equipment under the scheme. Your MCS installer will confirm eligibility for your project.
Planning a European-built solar and hot water system?
Tell us about your roof, your heat source and your hot water demand, and we will specify the right Eurener panels, Thermino model, Optimino key and accessories in one order.
Get a free quote Shop Sunamp Shop Eurener