One house,
going all-
electric.
Every part of the system, what it cost to run, and how it changes as the seasons turn. Installed 10 September 2026 by JEM Energy, Fleet.
Walk round
the roof.
The whole system as a 3D model: both roof faces of panels, the battery stack, the heat pump and the car.
On Apple Vision Pro, pinch and drag to turn the house.
The battery,
at full size.
The HiOne stacks in modules on a controller. Ours runs three 8 kWh modules: 24 kWh in total. Place it in your room to see the footprint before you buy.
View in your space ↗
The heat pump
that replaced gas.
A Grant Aerona R290, 9 kW air source heat pump. It uses R290 (propane) refrigerant and took over all heating and hot water when the gas boiler came out.
View in your space ↗
Episode · Why I'm getting solar, a battery AND a heat pump
01.The
Kit
Everything on and around the house. Installed 10 September 2026 by JEM Energy, Fleet.
01.Solar array
25 × 490W Aiko Neostar, south and west roof faces, Tigo optimisers
02.Battery
3 × Hoymiles HiOne 8kWh with a 12kW Hoymiles Energy Controller
03.Heat pump
Grant Aerona R290 air source. The gas boiler is gone.
04.EV charger
Zappi, scheduled by Intelligent Octopus Go
05.Export tariff
Not set up yet. Import on Intelligent Octopus Go.
06.Smart home
Home Assistant with Shelly devices
07.Shed, off-grid
DJI Power 2000 with two 425W Trina panels
Twenty-five panels,
one at a time.
Twelve and seven on the south roof, six facing west. Each panel has a Tigo optimiser that reports its own output.
Loading panel data from the Tigo optimisers…
Where the energy came from,
and where it went.
- Solar28.4 kWh
- Grid, mostly the 8p overnight rate7.7 kWh
- Of which stored and used later via the battery12.4 kWh
- House, including the heat pump19.9 kWh
- EV charging (8.4 kWh of it from solar)11.2 kWh
- Exported to the grid, unpaid4.6 kWh
- Battery losses0.4 kWh
Average day, 11 Sep – 10 Oct 2026 (27 days with complete data) · Hoymiles S-Miles, Octopus smart meter and myenergi Zappi readings
The 30 days before the install: gas boiler, and the cars charged at the standard rate
| Period | Before | Now | Saved |
|---|---|---|---|
| First 30 days · 10 Sep – 9 Oct | £232 | £102 | £129 |
| Next 30 days · from 10 Oct | — | — | In progress |
Grid electricity and gas from Octopus smart-meter readings, priced at the rates in force each day, including standing charges. Public charging and the Polestar Charge subscription aren't included. Year-on-year comparisons start in November, when last year's smart-meter data begins. Updated 11 Oct 2026.
Research and quotes
Why JEM Energy, and why the HiOne.
G99 application
Permission from the network operator for a system over 3.68kW.
Install day
Panels, batteries, controller and heat pump in.
First month of data
Battery tuning and tariff settings.
First cold season
Heat pump SCOP in real conditions.
Export tariff
Choosing an outgoing tariff once the data is in.
