This year saw the Feed-in Tariff closed to new applicants, leaving a very different landscape to the heady days of 2010, when the feed-in tariff scheme was first launched and the subsidy was around 43p per kWh. So, are solar panels worth it today?
Speaking purely from a financial point of view, the answer is a resounding yes. Of course beyond the financial, there are many other environmental benefits to be gained from installing solar, installing residential battery storage, driving an electric vehicle etc. Not least because they all contribute directly or indirectly to tackling air pollution, which, we are told, is gradually destroying the nation's health.
Back to the financials. The solar subsidy may have fallen, but so has the cost of the technology. Overall the cost of domestic solar electricity is now around 9p per kWh. This is well below the 15p average domestic import cost from the grid (which, by the way, increased by 7% in the last 12 months...).
The economics of solar in 2019
A typical 4 kWp solar system (13-16 panels) now costs around £5,500 incl VAT. There will be some maintenance costs over the life, and a probable inverter replacement required, total cost around £2,500 in today's money. So the true all-in cost of the system is around £8,000.
On average a system will generate an average of around 3,500 kWh a year, allowing for a modest degradation over time. In its 25 year life, it is expected to generate about 88,000 kWh of electricity.
The unsubsidised cost of solar
Ignoring Export Tariff payments for now, that means each kWh generated costs 9p:
|kWh from 4kWp system over 25 years:||88,000|
|System cost including VAT:||£5,500|
|Lifetime maintenance cost (present value):||£2,500|
|Total system cost:||£8,000|
|Un-subsidised cost per kWh:||9p|
Obviously to get maximum benefit from electricity that costs only 9p per kWh, you need to be using as much of it as possible on site, displacing imported electricity which could cost as much as 18p per kWh (on a time-of-use tariff), or 20p per kWh on a typical Economy 7 tariff. These time-of-use tariffs will then allow you to buy cheap electricity at night (at 8p per kWh, say).
If you don’t use the solar electricity (or store it), it won’t be worth that much to you - it will only be worth the Export Tariff, around 5p per kWh.
So with a ‘time-of-use’ tariff, you will gain around 9p per kWh by displacing expensive daytime electricity, and lose around 4p per kWh on anything you export. Without a battery, as long as you use at least 50% on site you are going to be ‘quids in’.
Solar plus domestic battery storage
With a battery and a ‘time-of-use’ tariff, you will easily use 70-80% on site, and open up the potential to top up your battery (and your car) with cheap overnight electricity, whilst avoiding altogether the high daytime tariff inherent in a ‘time-of-use’ tariff.
The stored electricity will cost you a bit more than 9p per kWh (more like 20p per kWh all-in), because of the cost of storage, but you will minimise export, still benefit from the cheap overnight rate of the time-of-use tariff to charge your car and top up your battery, and, with a Powerwall 2 for example, you have the added bonus that your lights will still be on in a power cut.
Conclusion: solar is still a very good investment!
As long as you use at least 50% of your power on site, then, with a judicious choice of import tariff, solar will make sense. The more you use on site, the greater the savings. Using everything on site gives a cost well below the average home's grid electricity cost of around 15p per kWh, and even further below a typical peak time-of-use tariff of 18p per kWh..
What's more the cost of grid electricity is rising. According to Page 6 of the Government's latest "Quarterly Energy Prices" publication, domestic electricity prices rose by 7.4% when comparing Q4 2018 with Q4 2017...
On a financial return basis, the internal rate of return (IRR%) from an investment in a solar system is typically 8% over the life, non-taxable and linked to inflation. How many other investments yield 8%, dependent only on the sun continuing to shine?