There’s been significant growth in solar panel installations, as more of us look for ways to become energy-independent (or at least offset some costs).
Having had solar installed recently (check out my BOXT Solar review for more details), I’ve had time to crunch some figures and do some testing to really get into how good solar is and whether it’s worth investing in.
A note on the price cap
How long solar panels take to pay back depends on a lot of things, but one of the most important ones is the amount you would otherwise have to pay for electricity.
While the current price cap will see electricity prices fall from April 1, the market remains quite unstable, and the situation in Iran could well lead to price increases three months later.
Despite that instability, the one thing that seems certain is that we’re unlikely to suddenly be able to buy clean electricity at such a low price that solar panels would be hard to justify.
In general terms, the payback time shouldn’t fluctuate too much. If anything, rising electricity prices will actually make solar seem like a better value.
So, in the UK, home of the constant drizzle and cloudy days, is solar really worth it?
It depends on your roof
Solar panels need sunshine, and the peak time for sunshine is between 10am and 4pm. Between these times, you need to have an unshaded roof. Ideally, this means a south-facing one (or near enough), but you also want to avoid shade from neighbouring buildings or trees.
If you have a south-facing roof, but it’s in shade a lot of the time, solar’s not going to be for you.
If you have a north-facing roof, then solar panels are most likely not worth it, either. You may get some sunshine on your roof at the peak of summer, but you’ll get a lot of shade for the rest of the year.
East-west-facing roofs may be doable, as you’ll get some periods of direct sunlight, but it’s worth looking at the plan your chosen solar provider will give you to work out whether it’s worth it.
Finally, you need a suitable roof structure. A sloped roof is standard, and makes installation easier. Flat roofs are harder to deal with and need specialist mounts for the panels; some solar suppliers won’t work on flat roofs at all.
It’s a long-term investment
Typically, you’re looking at eight to 12 years to recoup the cost of your solar panels. With my solar installation (2.37kW via five panels), the payback time is estimated at 11 years – on a south-facing roof.
The type of array you have, the number of panels, and the price you pay will all affect the payback time, and you should be given an estimated payback time when you get a solar panel installation quote. However, whatever your circumstances, the payback time is still in that kind of ballpark.
If you’re thinking of moving, then solar’s probably not for you: it won’t increase the price of your home, and you can’t shift the installation to a new home.
Solar panels will work for 20 to 25 years (and possibly even longer), so once you’ve covered the cost of them, everything else ongoing is just free electricity.
You need to maximise your solar usage
Solar panels are most effective when you use the energy that they produce. At the current price cap, electricity costs 27.69p per kWh. Every kWh that your solar panels generate and you use saves you 27.69p, so use the power while you can.
That largely means keeping an eye on solar generation and then using heavy-use appliances while the sun’s out and you’re generating power.
That can mean shifting how you do things. I tend to keep an eye on the weather and solar generation, and then try and use the washing machine, tumble dryer or dishwasher while there’s an excess of power, so that the cycle effectively becomes free (well, bar the cost of water).
For a typical installation, you’ll likely only have enough solar generation to run one appliance at a time, so try to stagger use where you can, say running the washing machine first, and then the dishwasher.
It’s also worth looking at the appliances you have, and looking at lower power options. For example, a low-power kettle may draw 1000W; a regular kettle is 3000W. Now, there’s no difference in the total power consumption required to boil water; it’s just that the 1000W kettle takes three times as long to do the same job.
However, the 3000W kettle will likely draw more electricity than you’re generating, requiring grid energy as a top-up; the 1000W kettle will be slower, but you’ll be able to use all of the power that you’re generating.
Similarly, if you have an electric heater, choosing a lower-power model or one where you can turn the power mode down, can help you stay within the limit of what you’re generating.
It’s worth charging devices while the sun’s out, too. If you have a portable power station, then charge this while the sun’s out, and remember to look in the settings to see if you can reduce the charging power: it will take longer to charge but you’ll use the energy you’re generating.
Get paid for what you don’t use
What you don’t use, you should get paid for by exporting it to the grid with a Smart Export Guarantee (SEG) plan. How much you get paid is highly variable, depending on the supplier that you choose. I’m with Octopus, so eligible for Outgoing Octopus, which pays 12p per kWh of electricity exported (this was 15p per kWh until very recently).
However, the standard Octopus SEG tariff pays just 4.1p per kWh, which is better than nothing (although not by much).
To export electricity, you need a smart meter that can measure export amounts and an export MPAN, which you can apply for once your solar panel installation is complete.
Exporting electricity can make a big difference. On March 5 (a very sunny day), solar power generation was such that I used just 7.33kWh of power (£2.44 including the standing charge), but I exported 7.12kWh (£0.85). That brings my electricity usage down to £1.59 for the day.
As you can see the total exported is similar to the total used; if I’d have been at home that day and could have shifted some of my electricity usage into the day, I could almost wipe out my electricity costs for the day. As we move into the summer months, that’s where I expect to be.
What about batteries?
I’ve covered batteries for solar before, but I will go over the basics. On the face of it, batteries seem like a good idea: you store the power you generate for free, and then release it later.
However, you need to account for the price of the battery and how much it costs you, over the battery’s lifetime, to store each kWh of power. And, you need somewhere to place the battery, which isn’t always easy (it turns out that, in my case, those pesky Victorians didn’t think about solar batteries when they built my house around 1875).
Due to the inverters required to convert between DC power (the battery) and AC power (your house), there’s some inefficiency involved in storing power. Again, the best thing you can do with solar power is use it while it’s there.
If you generate a good surplus each sunny day, then a battery can be worth it. In my case, I typically don’t have enough spare power to top up a small battery, and didn’t have much space to have one, so I didn’t bother. Every home is different, so do your sums and work out whether you want to store your spare generated power or just export it and get paid for it instead.
In conclusion, solar panels are worth it under the right conditions
Provided you’re planning to stay in the same home for long enough and you have the right type of roof, solar panels are well worth the investment in the UK, and they will help cut your electricity bills.
