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in depth posts
Fundamentals- Use the calculator to estimate how much you can save with a battery.
- Yes, it’s worth it. A 16.1kWh battery on Octopus Go pays for itself in 3.2 years — no solar panels needed.
- Save £5,200–£7,700+ over 16 years using cheap overnight electricity and discharging during peak hours.
- System cost ~£3,300 (battery + inverter + electrician). 0% VAT until March 2027.
- From 15 April 2026: BS 7671 Amendment 4 is published and in force, and Chapter 702 is the first UK wiring standard for home batteries.
- Best tariff: Octopus Go (7.5p overnight → ~28.5p peak = 21p spread). Start with battery, add solar later.
Fundamentals- Use the calculator to estimate your numbers based on your setup.
- Series wiring adds voltage — use when panels face the same direction and have similar specs.
- Parallel wiring adds current — use when panels face different directions or have mismatched specs.
- Check your inverter limits: Voc per string must stay below max input voltage, Isc must stay below max input current.
- Mixed panels? Match Imp (current at max power) for series, match Vmp (voltage at max power) for parallel.
Fundamentals- There is no single perfect solar angle — the best roof setup depends on season, orientation, shading, and when your household uses power.
- Flat and shallow roofs can work well in summer, but winter yield and self-cleaning are weaker than steeper installations.
- Vertical and wall-mounted panels are not pointless; they trade lower annual yield for useful winter and shoulder-season generation.
- Use ROI, not peak output, to compare roof types — the best option is the one that produces valuable energy when you can use or export it.
Fundamentals- Supplier
- Tariff
- Rate (p/kWh)
- Conditions
- Low-interest or zero-interest loans for solar panels and batteries
Fundamentals- Overpaneling increases UK annual yield, especially in winter and low-light conditions.
- The key metric is DC/AC ratio — oversize within inverter and DNO limits.
- Done correctly, it improves ROI without automatically requiring a bigger inverter.
Fundamentals- MC4 connectors are the universal standard for solar panel DC connections.
- Use genuine MC4s — knock-off connectors may not seal properly and can cause arcing or water ingress.
- Solar cable must be UV-rated and sized for the current. 4mm² or 6mm² is standard for residential strings.
- Never mix connector brands on the same circuit. Male/female must be from the same manufacturer.
Fundamentals- Roof hooks + rails are the standard UK mounting system for tiled roofs.
- Hook type must match tile profile: plain tile, slate, pantile, and concrete all need different hooks.
- Budget £150–£300 for mounting hardware on a typical 8–12 panel system.
- DIY-friendly: mounting is the most physically demanding part but technically straightforward.
Fundamentals- Series = more voltage, parallel = more capacity. Most UK home systems use 48V parallel for easy expansion.
- Match batteries carefully: same chemistry, same capacity, same age when connecting in parallel.
- Use proper busbars or cables rated for the combined current. Undersized cables are a fire risk.
- BMS handles balancing but only within spec — mismatched batteries will drift and degrade faster.
Fundamentals- Optimisers are most useful on imperfect roofs with shading, mismatch, or complex layouts.
- On clean unshaded arrays, gains may be small relative to added hardware cost.
- Use measured yield impact and system complexity to decide if they are worth it.
