| Solar Energy Concepts

§ Archive

Energy Utilisation

Home Battery Cheap-Rate Charging Calculator

Check the battery fills before the cheap window closes: the finish time is usable kWh to add divided by your charge rate, compared with the window length.
Tonight’s cost is grid import times your off-peak rate: the honest figure is the effective cost per usable kWh, your off-peak price divided by round-trip efficiency.
At 8.5p off-peak and 85% round-trip, stored energy costs about 10p per usable kWh: well under the 26.11p day rate in the example, so at this spread overnight charging pays after losses; a narrow spread may not.
Windows differ sharply: Octopus Go runs 00:30 to 05:30 (5 hours), Economy 7 gives about 7 hours, and Intelligent Octopus Go guarantees a 6-hour whole-home window from 23:30 to 05:30.
Degradation is a real cost per cycle: my Fogstar bank dropped about 10% after 800+ cycles against a 4,000-cycle rating, so a thin spread is not worth the wear.

Read Entry →

Energy Utilisation

Octopus Agile Home Battery Strategy: When to Charge, Hold or Wait

Octopus Agile home battery strategy in one rule: charge in the cheapest half-hours, hold headroom for tomorrow’s solar, discharge through the 16:00-19:00 peak, and leave the battery alone on flat days.
Charge against tomorrow’s published prices: Agile posts 48 rates around 4pm, caps import at 100p/kWh, and pays you during negative plunge-price events.
Leave headroom when the forecast is bright: a battery already full at sunrise has nowhere to put free solar, so the grid kWh you bought overnight is wasted.
Every needless cycle costs about 10% round-trip plus battery life: if the spread is under a tenth of the price you avoid, doing nothing beats cycling.
Static timers are too rigid for Agile: bridge Solar Assistant to Home Assistant and the Octopus API to schedule against half-hourly prices, and never write a zero current.

Read Entry →

Practical and DIY

Retrospective Building Regulations Approval for Solar Panels (UK)

Retrospective Building Regulations approval for solar panels is a regularisation certificate: apply to local authority Building Control, do not buy one after the fact.
The notifiable part was the electrical connection: “no building regs for the panels” almost always means the consumer-unit connection was never certified.
Regularisation is an inspection, not a purchase: the council can open up the work and require alterations before it issues the certificate.
Some evidence only a professional can produce now: an EICR from a registered electrician feeds the application; you cannot self-certify Part P work after the fact.
Doing nothing bites at sale: since October 2023 a section 36 notice can be served up to 10 years after the work was completed, and indemnity insurance is usually voided if you approach the council first.

Read Entry →

Practical and DIY

Selling a House with DIY Solar Panels: The Documents You Need

You can sell a house with DIY solar panels without MCS: hand over the electrical certificate, Building Regulations evidence, the DNO letter and any export agreement instead.
The electrical sign-off is the document that matters most: an EIC plus a Part P Building Regulations or Building Control certificate for the consumer-unit connection.
If it was never certified, fix it before you list: get an electrician to certify the work, apply for a regularisation certificate, or fall back to indemnity insurance.
The TA6 form asks about solar at question 5.6: you answer “owned outright” and attach the export agreement; no MCS number exists for a self-build.
The conveyancer and lender decide, not this checklist: a complete folder turns a sale-blocking enquiry into a five-minute one.

Read Entry →

Practical and DIY

Solar Panel Removal and Reinstallation Cost UK: What It Costs and Who Does What

Solar panel removal and reinstallation is three costs plus parts: access, panel handling and recommissioning, usually high hundreds to low four figures.
A re-roof with panels needs a roofer and a competent solar electrician: the mounting-to-roof interface is where leaks start if nobody clearly owns the weatherproofing.
Photograph and list every serial number before removal: it protects your warranty claim and proves the same hardware went back on.
A like-for-like lift is not a new installation: keep the original MCS certificate, and FIT or SEG payments follow it unless you change capacity, which needs an amendment through your installer.
Do not assume 0% VAT on removal and refit: the relief is written for installing panels, and roofing work is standard-rated, so get the treatment confirmed in writing.
Take a seven-question checklist to every quote: itemised costs, who holds BS 7671 competence, and who weatherproofs each roof anchor when the panels go back.

Read Entry →

Practical and DIY

Solar Panels on a Flat Garage Roof UK: Weight, Wind and Waterproofing Checks

Solar on a flat garage roof is usually possible, but it is a structural job first: the ballast holding the array down, not the panels, is what loads the roof.
Panels add about 15kg per square metre, ballast adds 30 to 60kg or more: the ballast is set by a site wind calculation, not a fixed rule, and is the load that grows on exposed plots.
Wind uplift is worst at the roof edges, so a small garage roof is nearly all edge; a low 10 to 15 degree tilt cuts the ballast a flat-roof array needs.
MCS MIS 3002 requires a structural engineer to assess the load on a ballasted flat-roof array: the panel-plus-ballast load can rival the roof’s entire code-minimum allowance, so do not judge it by eye.
Protect the membrane: seal every penetration to the EPDM, felt or single-ply type, and keep ballast clear of the drainage paths so water still reaches the outlets.
The checks are cheap next to the array: the ballast calculation usually comes free with the mounting kit, and a structural engineer’s assessment is typically a few hundred pounds.

Read Entry →

Practical and DIY

Solis OV-G-V01 Error: What a Grid Overvoltage Trip Means in the UK

Solis OV-G-V01 means the grid voltage crossed the inverter’s first overvoltage stage, about 262.2 V under UK G98/G99, so it shut down to protect the grid. The 253 V ceiling is the sustained statutory limit.
The number tells you the cause: OV-G-V01 is a breach of the first stage-one limit, OV-G-V03 is a sustained 10-minute average overvoltage.
Your inverter reads higher than the grid: exporting raises voltage across your own cable, which is why trips cluster at midday.
Check the voltage at rest to place the fault: high before you generate is the DNO’s duty to fix; high only under export points at your cabling.
Do not raise the protection thresholds: they are fixed by G98 or G99, and widening them lets you push an already-overloaded network higher.

Read Entry →

Fundamentals

Will My Solar Battery Work in a Power Cut? (UK)

A grid-tied solar battery shuts down in a power cut: you keep power only if a backup output was installed, wired and earthed for safety.
Check your own system in minutes: look for an EPS or backup output, a backed-up circuit, an earth rod, and a reserve setting in the app.
Backup needs several parts at once: a backup-capable inverter or battery system, a charged battery, safe grid isolation, and your chosen circuits wired to the output.
Three designs, rising in cost: a single backup circuit, an essential-circuits board, or a whole-home gateway that runs the house automatically.
Runtime is roughly usable kWh divided by load: a 0.3 kW essentials load runs about 15 hours on 5 kWh, but a few-kilowatt backup output cannot run an electric shower.
A backup output is not a UPS: the switchover gap can reboot computers and some routers, so add a UPS for anything that cannot blink.

Read Entry →

Practical and DIY

Solar Panel Bird Proofing: Is Mesh Worth It in the UK?

Solar panel bird proofing is usually worth fitting: clip-on mesh around the array stops pigeons nesting in the gap, often advertised around £300 to £900 fitted.
Fit it at install time if you can: it is cheapest while the scaffold is already up, so ask for it as a written line item on a new install.
Keep it clip-on, not drilled: mesh that grips the frame leaves no roof damage; drilling the panel frame voids the warranty and needs a roofer.
Check for an active nest first: intentionally sealing mesh over a nest in use is an offence under the Wildlife and Countryside Act 1981.
Access is the real cost: materials are cheap; the price is driven by roof height and safe access, not the mesh itself.

Read Entry →

Practical and DIY

Add a Battery to Solar Panels Without Losing Your Feed-in Tariff

You can add a battery and keep your Feed-in Tariff if the generation meter, and any metered export, still records eligible solar correctly.
AC-coupled after the generation meter is the low-risk route: it leaves your certified PV system and its meter untouched, where a hybrid swap re-wires the generating side and has to be re-proven.
Deemed export stays at 50% of generation: solar PV up to 30kW keeps the 50% deemed rate even with a battery and a smart meter, because it is read off the generation meter.
Grid charging is allowed but must be metered cleanly: if a meter cannot separate exported solar from exported grid electricity, you lose the export payment.
Report the change to your Feed-in Tariff licensee: notifying co-located storage with a wiring diagram and battery details is a scheme requirement, not a courtesy.

Read Entry →