Answering your questions about solar panels

Posted in: Solar Energy

Posted on: 26.05.2021

Solar panels are becoming cheaper and more widespread, with almost 1 million homes having them on their rooftops. Whether you already have panels or are thinking of getting them, we answer some of your questions about installation, upgrades and making the most of the green power they generate.

Is getting solar panels still worth it now that the Feed-in Tariff has ended?

When the Feed-in Tariff (FiT) scheme launched in 2010, generators got paid for the electricity they generated, as well as for the electricity they exported to the grid. Even though the FiT scheme is now closed, there are still benefits to installing solar panels.

For example, you’ll save on electricity bills because you’ll be generating renewable electricity at home – also helping to reduce carbon emissions. The cost of solar panels has also decreased. According to government data, in 2020 the average cost per Kw installed is £1,562 – a 25% reduction compared to 2014 prices. For reference, installers recommend a 3-4Kw system for an average family.

What’s more, energy suppliers are introducing payments to replace FiT payments under the smart export guarantee. This will enable people to get paid for electricity that they export to the grid. Good Energy is currently developing a smart export guarantee tariff.

Do modern solar panels produce more electricity than older ones? Is it worth upgrading my panels?

Modern monocrystalline solar panels are more efficient than older polycrystalline models, which enable them to generate more electricity. If you’re thinking about upgrading an existing solar array and are registered to the FiT scheme, be aware that increasing the capacity of your installation may mean you’re no longer eligible for payments.

Another way to potentially increase the performance of your existing array is changing your inverter. If you have a string inverter – which means all panels feed into the same inverter – a fault with one panel reduces the power output of the whole set. This could also be the case if a number of your panels are frequently in the shade or get covered with leaves.

Solar panels on the roof of a detached house.

Microinverters are attached to each panel separately, which means that an individual panel’s performance doesn’t impact the rest of the array. Microinverters are more expensive, but have a longer lifespan – 25 years, in comparison to 10 for a string inverter.

How does the direction panels face affect how much electricity they generate?

In countries in the northern hemisphere such as the UK, south facing solar panels have the best chance of being exposed to direct sunlight throughout the day.

However, south-east and south-west facing solar panels are still effective – receiving up to 95% of the sunlight received by south facing panels. This percentage reduces the further east or west they turn, but only to around 80%.

Even north facing panels can receive around 60% of the sunlight of south facing panels. This is because they still receive diffuse light – and may also be placed at an angle where they can benefit from direct sunlight during the summer, when the sun is directly overhead. Reductions in the amount of power generated compared to a south facing array can be somewhat mitigated by adding more panels.

South-east and south-west facing solar panels are still effective – receiving up to 95% of the sunlight received by south facing panels

It’s important to note that the pitch of the panels also impacts how much electricity they generate. If you want to read about this in more detail, have a look at this article from Solar Power World about the impact of direction and roof pitch on panel efficiency. If you’re considering getting panels, installers should also be able to advise you on how they will perform.

Do solar panels require direct sunlight to be effective?

Solar panels will generate the maximum amount of power in direct sunlight. However, they still react to diffuse light, which means they still generate electricity on cloudy days.

Can solar panels be noisy in the rain?

As panels are mounted above your existing roof tiles, they shouldn’t be noticeably noisier in the rain.

How can I make the most of having solar panels?

The first thing to do is know how much electricity your panels are generating. Your inverter display should indicate how much electricity is being produced. Then you could match this to the electricity consumed by appliances you want to use. For example, you could plan to run the washing machine on days when you know it’s going to be sunny, or use the dishwasher in the middle of the day rather than in the evening. If you have an electric car, charging up on sunny days is a great way to make the most of your solar power.

Installing a home battery will help make sure that your home can store any solar power not used straight away. If you’re registered to the FiT scheme, bear in mind that installing a battery could affect your payments, depending on whether it works by storing solar electricity before or after it has passed through the inverter and been measured by your generation meter. Read this guide to different battery configurations to find out more about this.

Hand plugging a charging cable into an electric car.

Other options for making the most of your solar power include installing a diverter. This diverts electricity that isn’t being used by household appliances to an immersion heater, so that you can use your solar panels to heat your water as well. 

I have solar water heating panels – what’s the best way to top up hot water while minimising gas boiler use?

A solar water heating system can supply between 40-70% of the hot water used by an average family of four. This means you will need to top it up with another heating method, such as a boiler or immersion heater – especially during winter.

Solar water heating guides recommend setting your boiler or immersion heater to come on first thing in the evening to top up heating that’s occurred during the day. This means hot water will be available later that evening and the following morning.  If you need to use lots of hot water earlier in the evening, you may need to set the boiler to come on slightly earlier. You may also need to adjust the timings during winter when daylight hours are shorter.

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