Power through the 4kWp home ‘limit’ with CSP

Been told you can only have 4kWp on your roof? Well, it’s not true! Our owner has over 5kWh on his – & so can you

It’s something we hear time and time again in our industry: domestic solar PV installations are limited to 4kWp. In reality, that’s nothing more than lazy sales talk – it’s not true, and never has been. The myth comes from the Feed-in Tariff rates, which were launched in 2010. Due to technological standards at the time, it was reckoned that 4kWp was about as much as anyone could expect to generate from a domestic setup, and FIT rates were therefore geared towards systems of 4kWp and below. Hence, in 2011, the basic rate of FIT for a 4kWp installation was 43.3p per kWh produced; for 4-10kWp systems, it was 37.8p. That means you were getting paid 5.5p less for every kWh produced – even if your setup was only 0.01kWp over the threshold!

Coupled with the high installation costs back then, this meant it wasn’t really worth getting over 4kWp, unless you could produce way over 4kWp – unlikely on most domestic roofs. Since then, the situation has changed markedly, with installation being much cheaper, and panels being lots more efficient. Added to that, the current FIT rates are 12.47p/kWh for 4kWp systems, and 11.30p/kWh for 4-10kWp systems, so the difference is minimal.

Let CSP put in the extra energy

Of course, installation is slightly pricier: 4kWp is around £5500-£7800, and 5kWp works out at about £1k more. But don’t forget, with the FIT almost disappearing in January 2016, maximising value from your solar setup is now just a question of maximising the energy it can generate. So you’d be crazy not to consider going larger. Although there is technically no limit on the kWp it’s possible to install on your roof, the amount you are allowed to install depends on your local grid, who will normally define an arbitrary maximum. As part of our commitment to an impartial, comprehensive service, we’re more than happy to put in the extra effort to find out how much you’ll be allowed to produce.

Tony’s house: 5.175kWp on the roof

As we’ve mentioned in a previous article, Tony has been using his own house as a solar guinea pig for the last few years. The year before last, he had a standard 4kWp system (technically it was 3.924 kWp…), built by SunPower. It managed to produce a whopping 4.777kWh – a record for a 4kWp system, as far as he’s aware. However, since then he’s upgraded to 5.175kWp. It’s predicted to produce 5499kWh by the end of the year, though Tony suspects it could actually produce over 6kWp. Tony’s next upgrade will be the Tesla Powerwall storage battery: a development that will allow him and his family to store all the energy their panels produce throughout the day, and continue using the excess at night. With storage, it’s a real possibility that they can become entirely energy-independent: not having to draw from the national grid at all, and eliminating their energy bill!

It might sound unbelievable, but the future of how we power our homes is in solar and storage. And it’s here from 2016.



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