How Much Will a 21 kW Solar System Save?
An 21 kw solar system for the right home or business should save around £81400 over the course of its expected 25 year lifetime. That’s based on grid electric costing £0.28/ kWh (last updated April 2022). That’s roughly £3255 per year in savings, without taking into account inflation or rising electric prices (which both add to your savings if you invest in solar soon).
Rising Electric Costs
The cost of electricity in the UK has consistently ‘outperformed’ inflation. You can see the last few seasons of price rises in this chart of Ofgem’s price cap rises:
The amount that electricity costs continue to rise will have a large impact on whether you decide if solar is worth it for you in the UK.
Smart Export Guarantee
The Smart Export Guarantee replaces the older Feed in Tariff scheme. It allows you to get paid for excess energy that your 21 kw solar system produces but you don’t directly use yourself, for example if you’re out during the day when it’s sunny.
Currently you can expect to get up to 7.5p per kWh of electricity you ‘export’, so for a 21 Kw solar system, with typical usage patterns, you could expect to receive around £803 per year in payments under this scheme. This rate is available at the time of writing from Octopus Energy.
One of the main reasons to consider getting an 21 kW solar system is to save money by directly using the electricity it produces during the day, instead of paying the utility company. The more of your own ‘self generated’ electricity you use instead of buying it or paying for petrol if you’re also buying an electric car, the higher your savings.
With a properly sized 21 kW solar system, you can expect to save around £2452 per year by using your own solar energy.
21 kW Solar Panel System Price
An 21 kW solar system (without a battery) typically costs around £26000 in the UK. That’s including installation and VAT.
How Many Solar Panels for 21 kW System?
Modern solar panels are rated for between 300 – 500w each, or 0.3kw – 0.5kw. That means that you would need between 42 and 70 individual panels for a 21 kW system.
How Big is a 21 kW Solar Array
Each solar panel is around 1.6 m㎡, so in total a 21 kW solar system would need between 68 m㎡ and 114 m㎡ of space, depending on if you go for the more efficient (but also more expensive) panels, or the less efficient ones.
How Much Does a 21 kW Solar System Produce? (In the UK)
On average over a whole year a 21 kW solar system produces 19463.95 kWh in the South of the UK.
There’s several factors that influence how many kWh a 21 kW solar PV system produces. Those are:
- Location in the UK
- Roof direction and tilt
- Time of year
- Efficiency of components in your system
Is a 21 kW Solar System Right For You?
To find out if it’s worth it for you, use our free solar panel cost calculator.