Most homes that go electric end up with three separate systems from three separate brands: solar panels on the roof, a battery in the garage and a heat pump in the garden. Each has its own app, its own control logic and no real idea what the others are doing. SolaX takes a different route. The SolaX X1-IES all-in-one energy storage system and the SolaX Thermal R290 heat pump are designed to work together, so your solar generation, battery and heating are managed as one system.
This guide explains how the combination works, how to size the IES, the heat pump and the solar array together, what you need for installation (including the Matebox, X-Hub and meters), and where an EV charger fits in.
The heat pump is the biggest electrical load in an electrified home. Pairing it with solar and a battery that can see and schedule it is where the real savings come from.
How the SolaX IES, heat pump and solar work together
The system has three parts that talk to each other: PV panels generate DC power, the X1-IES converts and stores it, and the R290 heat pump turns that electricity into heat at three to five times efficiency. SolaXCloud sits over the top for monitoring, scheduling and remote control.
Solar generates
PV strings connect directly to the IES's MPPT inputs. The IES accepts up to 200% PV oversizing, so an 8kW model can take up to 16kWp of panels and still use shoulder-season sunshine.
The IES stores and routes
Surplus solar charges the LiFePO4 modules (5.1kWh each, up to four per tower). The IES then supplies the house, the heat pump and any EV charger, exporting only what is left over.
The heat pump runs on your energy
The R290 heat pump is designed to integrate with PV and battery storage to maximise self-consumption. It is SG Ready and supports Modbus TCP/RTU, so it can be told when cheap or free energy is available.
Smart control ties it together
The IES's Smart Scene and intelligent load management features can prioritise the heat pump and EV charger, while 7×24 time-of-use scheduling lets the battery charge on cheap overnight tariffs.
What makes the SolaX Thermal R290 heat pump different
SolaX built its name on inverters and batteries, and that shows in how the heat pump is designed. It is an air-to-water monobloc that treats solar and storage as part of the heating system, not an afterthought.
🌿 R290 natural refrigerant
Propane refrigerant with a GWP of just 3, compared with 675 for R32. Only 1.2–1.5kg is charged in the sealed outdoor unit.
🔥 80°C flow temperature
Heating water up to 80°C and DHW from 25 to 70°C, which gives more room to work with existing radiators in older UK homes.
⚡ A+++ efficiency
SCOP of up to 5.44 at 35°C and 4.12 at 55°C on the 8kW model, with heating operation down to −25°C outdoor air.
🔇 Quiet operation
Sound pressure from 35 dB(A) at 1m and 32 dB(A) at 3m on the 8kW and 10kW models, using a brushless DC fan with stepless speed control.
☀️ Built for PV and batteries
Designed to integrate with solar and energy storage from the start, with SG Ready and Modbus TCP/RTU for third-party energy managers too.
❄️ Heating, cooling and hot water
One outdoor unit handles space heating, domestic hot water and 5–25°C chilled water for cooling, controlled through a smart app with OTA updates.
See the SolaX R290 heat pump
SolaX: Eco-friendly R290 heat pump with A+++ energy efficiency. Watch on YouTube
Sizing the IES, heat pump and solar together
The right pairing depends on your heat loss, your roof and whether you want whole-home backup. Your heat pump size should always come from a room-by-room heat loss calculation, and your installer will confirm the final design. As a starting point, these combinations match the IES inverter sizes to the heat pump range:
| Home type | Heat pump | X1-IES inverter | Battery | Max PV (datasheet) | DNO route |
|---|---|---|---|---|---|
| Smaller or well-insulated home, 2–3 bed | 8kW | 3.7kW | 10.2kWh (2 modules) | 7.4kWp | G98 notification |
| Typical family home, 3–4 bed | 10–12kW | 6kW | 10.2–15.3kWh | 12kWp | G99 application |
| Larger or older home, higher heat loss | 14–16kW | 8kW | 15.3–20.4kWh | 16kWp | G99 application |
Backup power and the heat pump: the IES EPS output is rated at the inverter's rated power (for example 6kVA on the X1-IES-6K and 8kVA on the X1-IES-8K). The heat pump compressor draws well within that, but the indoor hydraulic unit's 3kW + 6kW backup heater does not. If you want heating during a power cut, ask your installer to keep the backup heater off the EPS circuit or lock it out in backup mode.
The core products
Two products do the heavy lifting: the X1-IES energy storage system and the R290 outdoor unit. Every IES bundle includes the hybrid inverter, BMS, TP-HS50E battery modules and a Pocket-X dongle for SolaXCloud monitoring.
SolaX
X1-IES 8kW All-In-One Energy Storage System
8kW single-phase hybrid inverter with 5 to 20kWh of LiFePO4 storage, three MPPT inputs and up to 16kWp of PV. The best match for 14–16kW heat pumps and whole-home backup with a Matebox G2.
From £3,170.00 Inc. VAT
SolaX
SolaX Thermal R290 1-Phase Heat Pump 8–16kW
Single-phase monobloc outdoor unit in 8, 10, 12, 14 and 16kW. R290 refrigerant, 80°C flow, A+++ SCOP and heating, cooling and hot water from one unit. Needs one SolaX indoor unit to complete the system.
From £2,400.00 Inc. VAT
X1-IES sizes compared
| Model | Rated output | Max PV | MPPTs | Max AC current | EPS rated power | Battery options | |
|---|---|---|---|---|---|---|---|
| X1-IES-3.7K | 3.68kW | 7.4kWp | 2 | 16A | 3,680VA | 5–20kWh | View |
| X1-IES-6K | 6kW | 12kWp | 3 | 26.1A | 6,000VA | 5–20kWh | View |
| X1-IES-8K | 8kW | 16kWp | 3 | 34.8A | 8,000VA | 5–20kWh | View |
All IES models share the same battery platform: TP-HS50E LiFePO4 modules at 5.1kWh nominal (4.6kWh usable) each, 100% depth of discharge, more than 6,000 cycles and a 10-year warranty. The inverter is IP66 rated with Type II surge protection on both AC and DC sides, and the battery heating system allows operation down to −30°C.
R290 heat pump outdoor units compared (single-phase)
| Model | Heating A7/W35 | COP A7/W35 | Heating A-7/W55 | SCOP 35°C | SCOP 55°C | Sound 1m / 3m | Weight |
|---|---|---|---|---|---|---|---|
| STU1-C08R290 | 8.5kW | 5.15 | 7.5kW | 5.44 | 4.12 | 35 / 32 dB(A) | 140kg |
| STU1-C10R290 | 10kW | 4.95 | 9kW | 5.30 | 4.07 | 35 / 32 dB(A) | 140kg |
| STU1-C12R290 | 12.5kW | 4.90 | 11kW | 5.07 | 3.89 | 37 / 34 dB(A) | 154kg |
| STU1-C14R290 | 14kW | 4.75 | 12kW | 4.94 | 3.84 | 38 / 35 dB(A) | 154kg |
| STU1-C16R290 | 15.5kW | 4.55 | 13kW | 4.90 | 3.83 | 38 / 35 dB(A) | 154kg |
All models share the same 1310 × 1050 × 465mm casing, a rotary DC inverter compressor, electronic expansion valve and G 1¼″ water connections. Heating operates from −25 to 35°C outdoor air and DHW from −25 to 46°C. Three-phase STU3 versions are also available for larger properties.
Choosing the indoor unit
The outdoor unit needs one SolaX indoor unit. The right one depends on what hydraulics and hot water storage you already have.
| Indoor unit | What's inside | Best for | Price | |
|---|---|---|---|---|
|
Control Unit STN1-C01 |
Control board and 4″ touch panel. WiFi, Ethernet and RS485. Wall-mounted, 6.5kg. | Homes with existing or installer-built hydraulic circuits and a hot water cylinder | £495.00 | View |
|
Hydraulic Unit 1-phase STN1-C02 |
Control board, touch panel, 3kW + 6kW backup heater, 8L expansion tank, three-way valve. 60A breaker recommended. | Single-phase homes with an existing cylinder that want a plug-in hydraulic module | £1,200.00 | View |
|
Hydraulic Unit 3-phase STN3-C02 |
As STN1-C02, with a 380–415V three-phase supply and 20A recommended breaker. | Properties with a three-phase supply | £1,270.00 | View |
SolaX also makes a floor-standing Hydraulic Integrated Unit (STN1/3-C03) with a built-in 190-litre hot water tank, which suits new builds or homes replacing their cylinder. Ask us for a quote if that suits your project.
See the SolaX IES energy storage system
SolaX: X1/X3-IES integrated energy storage solution introduction. Watch on YouTube
Installing a SolaX IES, heat pump and solar system
A combined installation touches three trades: electrical, solar PV and heating. In the UK, grid-connected solar and battery storage should be installed by an MCS-certified installer, and the heat pump must be installed by an MCS installer if you plan to claim the Boiler Upgrade Scheme grant. Because R290 is a flammable refrigerant (propane), the outdoor unit must be sited and commissioned by engineers trained in handling it.
The R290 outdoor unit with its SolaX indoor controller.
Survey and design
Heat loss calculation for the heat pump, roof survey for the PV strings, and a check of the incoming supply and main fuse. The installer submits G98 (3.7kW IES) or a G99 application (6kW and 8kW IES) to your DNO before commissioning.
Mount the IES tower
The IES stacks as a base, TP-HS50E battery modules and the BMS/inverter on top, secured to the wall. Four modules need a Series Box and a second column. SolaX quotes around 30 minutes to assemble the modular tower.
Wire grid, EPS and metering
Connect the grid and EPS outputs, fit the CT or smart meter at the incoming supply, and connect PV strings to the MPPT inputs. For whole-home backup, the Matebox G2 handles the changeover wiring.
Heat pump and commissioning
Site the outdoor unit with the clearances in the SolaX manual, connect the water circuit to the indoor unit, fill and flush the system, then link the heat pump to the IES and SolaXCloud for combined scheduling.
Before you start: check your main fuse. A 1-phase hydraulic unit with its backup heater is rated at 39.5A, and the IES and any EV charger add to the load. SolaX's Smart Scene load management and a correctly set export and import limit help keep everything within a typical 60–100A supply.
Installation accessories
These SolaX accessories complete an IES installation. The bundles already include the Pocket-X dongle for monitoring.
| Accessory | What it does | Price | |
|---|---|---|---|
|
X1-Matebox G2 8000VA, IP65 |
Single-phase backup box that simplifies grid, EPS and changeover wiring. Used in SolaX's whole-home backup layout with the IES, heat pump and EV charger. | £670.00 | View |
| X1-Matebox Advanced | Alternative single-phase backup box for the IES. Your installer will confirm which Matebox suits your board layout. | £650.00 | View |
|
X-HUB DIN-rail |
Smart energy management controller that coordinates PV, battery, heat pump, EV charger and grid, as shown in SolaX's heat pump system diagram. | £320.00 | View |
|
CHINT DDSU666-CT 1-phase meter, 200A CT |
RS485 Modbus energy meter for single-phase installations, used for accurate import and export measurement. | £89.00 | View |
|
CHINT DTSU666-CT 3-phase meter |
Three-phase energy meter with 200A/5A CTs. The X1-IES can work in a three-phase property by adding a three-phase meter. | £145.00 | View |
|
M3-40-Dual 3-phase dual-channel |
Three-phase dual-channel CT meter (100A CTs) for measuring two circuits, such as grid and an existing PV system. | £179.00 | View |
| IES Wall Mounting Kit | Base support for mounting the X1/X3-IES tower securely. | £99.00 | View |
|
TP-HS50E battery Add-on module |
Extra 5.1kWh LiFePO4 module to expand an existing IES later, up to four per system. | £1,320.00 | View |
| Wi-BR Wireless Bridge | Wireless link with up to 200m range for sites where running a data cable to the meter is impractical. | £67.00 | View |
See the full range of meters, CTs and monitoring accessories in our SolaX collection.
Adding an EV charger to the system
SolaX's whole-home backup layout places a SolaX EV charger alongside the heat pump, with the IES managing both through Smart Scene load management. That means your car can charge from surplus solar in the day or cheap overnight rates, without tripping the supply when the heat pump is running hard.
| Charger | Supply | Best for | Price | |
|---|---|---|---|---|
|
SolaX Smart 7kW G2 Tethered, Type 2 |
Single-phase | Most UK homes, and the natural match for an X1-IES system | £375.00 | View |
|
SolaX 11kW G2 X3-HAC-11K, tethered |
Three-phase | Properties with a three-phase supply | £435.00 | View |
|
SolaX Smart 22kW G2 X3-HAC-22K, tethered |
Three-phase | Larger homes and light commercial sites with a three-phase supply | £495.00 | View |
The 11kW and 22kW chargers need a three-phase supply. If your home is three-phase, the X3-IES and three-phase STU3 heat pumps are usually a better fit than the single-phase X1-IES. Get a quote and we will design the right combination.
Frequently asked questions
Can I use the SolaX heat pump without the IES battery?
Yes. The R290 heat pump works as a standalone air-to-water heat pump. Pairing it with the IES and solar adds the ability to run it on stored or self-generated energy and to schedule it around cheaper tariffs.
Will the heat pump keep running during a power cut?
It can, if the installer puts it on the backed-up side of the system. With a Matebox G2 in a whole-home backup layout, the IES switches over in under 10ms. Keep the indoor unit's backup heater off the EPS supply, as its 3kW + 6kW elements would exceed the inverter's backup rating.
Which IES size do I need for a heat pump?
It depends on the heat pump size, your roof space and your DNO. The 3.7kW model qualifies for simple G98 notification, while the 6kW and 8kW models need a G99 application but accept more PV and deliver more backup power. For 12kW and larger heat pumps, the 6kW or 8kW IES is the better match.
Can I add more battery capacity later?
Yes. Each TP-HS50E module adds 5.1kWh, up to four modules and 20.4kWh per IES. The third and fourth modules use a Series Box in a second column.
Is R290 refrigerant safe?
R290 is propane, which is flammable, so it is sealed inside the outdoor monobloc unit with a small charge of 1.2–1.5kg. Only water runs into the house. Installation must follow the manufacturer's clearance and siting rules for flammable refrigerants and be carried out by trained engineers.
Does the heat pump work with radiators?
Yes. With a flow temperature of up to 80°C, the R290 heat pump can serve radiator systems as well as underfloor heating. Efficiency is highest at lower flow temperatures, so your installer may still recommend upsizing some radiators.
Plan your SolaX solar, battery and heat pump system
Tell us about your home and the AIZO Quality Heating team will match the right IES, heat pump, indoor unit and accessories, with a single quote.