Solar Energy Concepts

DIY Solar for UK Homes. Real guides from a real install.

Step-by-step practical guides, component lessons, and hard-earned fixes from a real UK DIY solar setup.

7.15kWpinstalled 6,072kWhgenerated 2025 £1,668/yrmodelled value

Latest field notes

My Components

After 3 years, my Fogstar packs report 87.5Ah to 89.3Ah of a rated 100Ah: about 0.018Ah lost for each counted cycle.
The three packs share the work evenly: since September 2024, each counted 367 to 372 cycles and lost 6.7Ah to 6.8Ah.
The pack that worked alone for a year is 1.7Ah behind: it arrived with about 95 extra cycles, and the gap has not grown since.
Octopus Go and Solar Assistant automation saved £1,668 in 2025: my exact charge settings are in the article.
Uneven charge readings came back together: a BMS firmware update and an overnight discharge limit fixed them in my system.

Updated 26 Sep 2026 Read Entry →

Practical and DIY

Solar Assistant + Sunsynk automation: Schedule charge and discharge current limits your inverter’s native app can’t handle.
Force solar export: Drop Max Charge Current to 2A during the day so surplus solar goes straight to the grid on Octopus Go.
Real UK export data: These rules helped double grid export from 1,766 kWh to 3,914 kWh year-on-year.
Crash-proof your setup: Never set amps to zero. Solar Assistant can crash and leave values stuck.
Home Assistant solar integration: Bridge Sunsynk data via MQTT for Octopus Agile pricing, solar forecasts, and EV diversion.

Updated 26 Sep 2026 Read Entry →

Fundamentals

You can buy a compliant plug-in solar kit now: 70 are listed on the ENA register, and Screwfix, City Plumbing and Argos all range them, from £336.
The cheap Amazon look-alikes are the trap: apart from Modular Solar’s own units, none I found was listed Compliant on 22 September 2026, and battery kits sit outside the law’s own definition of a plug-in microgenerator.
Compliance is a register listing plus six limits: 800 VA and 3.5 A from the inverter, 2,000 W of panels at STC, a moulded plug with a 5 A fuse, no extension lead, and no battery.
Budget £43-84 a year and a 5 to 14 year payback: 650-800 kWh at 25-40% self-consumption and 26.11p/kWh, rising to 26.32p on 1 October 2026. Export income is £0.
A Type AC RCD rules your home out until an electrician changes it: Type A, F or B is suitable, and the device also has to work with power flowing both ways.
Screwfix, City Plumbing and Argos range listed kits: Lidl, Aldi and B&Q had none on 22 September 2026.

Updated 23 Sep 2026 Read Entry →

Fundamentals

Plug-in solar is legal in Great Britain since 27 August 2026: 70 kits are listed Compliant on the ENA register, and Screwfix, City Plumbing and Argos all range them, from £336.
Only listed models count: the Amazon kits with a UK plug are unlisted or Non-compliant, and battery kits are excluded by the law itself.
Not every home is suitable: the IET and Electrical Safety First say a Type AC RCD rules a home out, and only 25% of adults know which type they have.
One device per household is now written into G98: the August 2026 amendment says connecting more than one “is not allowed”, so the per-circuit relaxation did not happen.
Realistic savings are £43 to £84 a year, not the government’s “up to £110”: 650 to 800 kWh, 25 to 40% self-consumed, £0 export. Payback 7 to 14 years on the £599 kit.
Already have roof solar? The 3.68 kW limit is cumulative per property, and G98 now says so for plug-in kits in terms.

Updated 23 Sep 2026 Read Entry →

Fundamentals

July 2026: there is no universal free solar grant for typical UK homeowners – self-fund with 0% VAT and SEG is the normal path.
Scheme map: VAT (near universal), SEG (export pay), ECO4 and Warm Homes (means-tested), group buy (discount only).
Free solar is rare: only where ECO4 / Warm Homes / Nest eligibility and delivery actually include PV.
Ignore lead-gen “free panels” ads that harvest details without naming a real qualifying scheme.

Updated 23 Sep 2026 Read Entry →

Fundamentals

Solar panels convert sunlight to DC electricity via photovoltaic cells. An inverter converts this to usable AC.
UK-standard panels: 430–490W, N-type TOPCon or HPBC cells, 22–24.5% efficiency.
Direction matters: south-facing produces ~978 kWh/kWp/year. East/west produces ~81% of that.
Panels last 25+ years with minimal degradation. The inverter and battery are replaced first.

Updated 23 Sep 2026 Read Entry →

Practical and DIY

Automate battery charging using Solar Assistant, PV forecasts, and overnight tariff rates to maximise winter savings.
Simplest setup: charge from grid overnight on Octopus Go at 9.5p/kWh between 00:30 and 05:30, discharge during peak hours.
Advanced: use Forecast.Solar API + Solar Assistant rules to decide whether to charge from grid or wait for solar.
Works with Sunsynk and Deye inverters via MQTT control through Solar Assistant.

Updated 23 Sep 2026 Read Entry →

Fundamentals

Use the calculator below to compare tilt, direction and 10-year ROI for your roof. It covers every UK region; the optimal angle barely changes across a postcode area.
The textbook optimum is 35-40° facing south, but east-west and even vertical setups beat it for many real households.
Flat roofs win summer, steep walls win winter. Match the angle to when you actually use power.

Updated 23 Sep 2026 Read Entry →

Fundamentals

Start with your goal, not the hardware: bill reduction, resilience, DIY learning, and export income lead to different system designs.
Roof direction and shading decide the first cut: a simple south-facing roof is easy; mixed, shaded, or small roofs need more design work.
Batteries change the economics by moving solar or cheap-rate electricity into expensive evening hours.
DIY can save money, but compliance still matters: inverter certification, DNO notification, isolation, and safe wiring are not optional.

Updated 23 Sep 2026 Read Entry →