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  • Writer's pictureThe Climate Coach

To solar or not to solar - that is the question?

There has been a huge amount of interest with rooftop solar in 2022 due to the rapidly increasing cost of energy in the UK. Many people are keen to get solar to help try and reduce their electric bills. So should you get involved?

With a bit of information about your consumption and your roof space, this should be a pretty straightforward question to answer from a financial standpoint. A reputable solar installer will also be able to give you a recommendation on what would work best for you - including estimated generation and time to return on investment. But as with any trades, and possibly in the case of solar in-particular because of the recent influx of new installers trying to cash in on the demand (and perhaps the lack of regulation currently), this definitely isn't always the case. From what I can see, there are plenty of installers who will quite happily quote and install a system which may not be suitable for you at all - and/or not do a great job. On the flip side, there are a lot of great knowledgable installers doing a great job! The challenge is to find the right ones.

What about from a climate perspective?

There's no two ways about it - solar panels are a great way to generate energy from a climate perspective. The materials used in modern solar panels are abundant (silicon) and usually over 99% of the materials used are recycleable so can be re-used again in the future. That said - because relatively few panels have actually come to the end of their useful life so far, the recycling part often isn't managed as well as it could be because there isn't enough panels coming through for it to be a readily available option yet. I am certain this will improve over time. They also have a very long lifecycle - with most coming with at least a 20+ year warranty and usually lasting up to 30 years.

The climate credentials of battery storage is not quite so clear cut - with rare earth minerals being required to make these (and thus mined). However, as with electric vehicle batteries (currently made from the same minerals) - this process is being improved all the time in order to reduce emissions created during production.

As with many things today - most solar equipment is made in China so there are associated transport emissions. However for panels, the transport emissions per panel are relatively low because you can fit so many in a shipping container. Battery storage doesn't perform quite so well here because of the weight and size being larger.

However the key for solar is the reduction on ongoing emissions from the energy you use. There are very few moving parts in a solar setup so in theory with a good installation with quality equipment you shouldn't need to replace any parts and obviously all the energy you generate does not have any associated ongoing emissions for the lifetime of the solar. So it's likely you will more than offset the production emissions during it's lifetime. That said - research into this topic specifically is quite limited. The focus is more on financial payback rather than climate.

Talk to me about ROI then....

At a high level, you can work out how much money you will save based on your estimated generation. As a very very rough estimate - if you multiple your total solar array by 700, that's a rough indication of how much you may get. So for a 4.3kWp array - you might expect to generate around 3,000kWh worth of energy over the year. For solar installations without battery, we'll assume you'll use 50% of all the energy you generate and for installations with a battery, we'll assume 80% (because you store your excess in the battery and use it later).

So let's assume you get a solar install that generates 3,000kWh per year. Based on the 80% scenario with battery, you'll essentially save yourself buying 2,400 kWh from the grid. Multiply that by the unit rate - (currently around 40p per kWh) and you'll save £960 per year. Your generation will reduce slightly each year - but the energy prices will also likely increase each year (at the moment who knows though!?) so as a very rough estimate, you can divide the total cost of the install by £960 to work out how many years it will take to pay back.

If the install cost £8000 - then the payback is roughly 8.3 years in this scenario.

This doesn't factor in any increase in the value of your house due to adding solar - nor does it factor in any maintenance or replacement parts that may be required throughout the systems life. The other thing it doesn't factor it in variance in energy prices - they could go up significantly in which case that payback period could be reduced massively - or on the flip side, prices could come down in which case it will take longer to payback.

Ok makes sense at a high level, anything else?

That is a very basic way to work out ROI of solar - however solar often opens up much more options which can further accelerate the ROI. For example:

  • Solar compatible electric car chargers (e.g. Zappi by myenergi) - these can take excess solar and direct it to your car rather than exporting to the grid. This obviously gives you free charge in your car - and if you've moved from a petrol car can represent significant savings.

  • Immersion heater diverter (e.g. Eddi by myenergi) - this works in a similar way to the Zappi above but diverts excess solar to a hot water tank immersion heater if you have one. Again - this basically provides free hot water heating using your excess solar so can represent further savings on oil or gas depending on what you use for this currently.

  • Adapting usage with solar. Another way you can improve the ROI is by shifting your usage around your solar generation. Common things can include running high usage appliances such as your washing machine when you have excess solar, or running the slow cooker for dinner during the day when you have solar rather than using the electric oven in the evening when you have none.

  • Off-peak electric tariff. If you have batteries included - you can look to move to a tariff which includes some off peak hours - where you could charge your battery to use this energy when you need it. This is especially useful in winter where your solar generation will be low.

These things can all add up to improve the % of your solar generation you use. In a best case scenario - let's say you manage to use 100% of your solar by taking the above steps, then actually you are saving £1,200 per year instead of £960 - which reduces your payback to roughly 6.7 years. In addition to this saving, if you are charging your battery off peak, you'll likely see further savings improving the ROI even further still - because you the electricity you do import is at the cheaper night rate.

I guess the key thing here is it gives you much more flexibility when it comes to your energy usage. Ideally - you'll want to be importing energy when generation to the grid is at it's greenest and then using as much of your solar as possible to maximise the positive climate impact.

I'm interested but I need more details...

We'll go into more detail on further solar considerations in a future post but hopefully this has given a good high level overview of solar from a climate (and cost) perspective. I've also outlined some FAQs below which may help

Can I go "off grid" when I get solar?

No - very very unlikely. Your solar will obviously only generate energy when it's light outside - so evenings, overnight and pretty much all the time in the depths of a UK winter, you won't be generating electricity. Batteries can help with this but again in winter, you will struggle to fill them just from solar - especially over a few days of bad weather.

If I use 3000kWh per year - do I just need to generate 3000kWh of solar energy per year?

Can I install solar myself?

Can any house get solar?

If you have any thoughts, feedback or ideas you wish to contribute on this or any other topic covered by The Climate Coach - please get in touch, we'd love to hear from you.

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