A misconception is that solar power performs dramatically worse in the UK than in Germany due to latitude. That is wrong, London is on same latitude as Dortmund, while Hamburg is on the same as Manchester. Solar potential is more comparable across these regions than many assume.
To evaluate the viability of a small solar installation in London, we can use the EU’s PVGIS calculator (which still works perfectly fine for the UK). Let’s define a realistic small-scale setup:
London scenario
- Location: London
- System type: Crystalline silicon
- System size: 0.8 kWp (typical balcony system)
- System losses: 14%
- Mounting: Vertical (90°, e.g. balcony installation)
- Azimuth: 0° (facing south)
Using these parameters, the system yields: Annual energy production: 614.65 kWh
This is a solid output for such a small installation, and there is really no need to tilt „better to the sun“ as that would only increase summer output, where we already have enough energy. Keep it vertical and catch the winter sun!
Now let’s translate that into economic terms:
- System cost: €500 (≈ £432.92) – German large distributors sell the systems for around 400 EUR, so we assumed the stuff is more expensive in the UK.
- Interest rate: 2%
- Lifetime: 15 years (Panel will last longer)
- Electricity price (London average): £0.249 per kWh – which we got from the Internet. Might be wrong.
- Self-consumption rate: 50%. This is an assumption we took from the HTW Cost Calculator based on German data. Standard Load Profiles in the UK might be diffrent but not that different.
Assuming half of the generated electricity is used directly: gives you a usable energy: 600 kWh × 50% = 300 kWh whtich translates to Annual savings: 300 kWh × £0.249 ≈ £74 per year. With annual savings of about £74: you get a Payback time: ≈ 5.4 years.
Even in London’s climate—and with a less-than-ideal vertical installation—a small balcony solar system can pay for itself in just over five years.
Inverness Scenario
Lets give a far worse example. We choose Inverness that gets far less sun then London.
Here the same 0.8 kWp system is installed vertically at 90°, but this time with west orientation (azimuth 90°). PVGIS gives a yearly PV energy production of 344.18 kWh. Again assuming 50% self-consumption, the annual savings are:
344.18 kWh × 1/2 × £0.249 = £42.85 per year
Rounded, that is about £43 per year. The payback period is then: £432.92 ÷ £42.85 ≈ 10.1 years
Conclusion
So even under bad circumstances, it will be benefical to the consumer over time.
Please proof us wrong!
Update: Carbon Brief has made their own calculations and they have similar numbers: https://www.carbonbrief.org/analysis-how-plug-in-solar-can-save-uk-homes-1100-on-energy-bills/