Solar panel add-ons you don't need

Three quarters of solar panel owners have been approached by companies trying to sell them unnecessary solar panel products or services they didn't ask for, new Which? research reveals.

The most common thing owners were approached about in the past two years was solar panel servicing - a check to make sure your PV system is working correctly. More than a third (36%) of the solar panel owners we spoke to said they had been approached uninvited about this.

Voltage optimisers and replacement inverters were the next most-common products companies approached solar panel owners about in the past two years.

Have you, or has someone you know, been offered solar panel servicing, a new inverter, voltage optimiser or other solar PV products or services? Read on to find out whether they're worth considering.

See the best solar panel brands according to owners.

Solar panel products and services available

We've heard from Which? members who have been approached by companies offering solar panel cleaning, servicing, and various add-on products. So we asked over 2,000 solar panel owners* about their experiences.

Solar panel owners are most likely to be approached about solar panel servicing, according to our survey, followed by voltage optimisers, replacement inverters and solar buyback.

Have you been approached with these solar panel products or services?

• 36% have been offered a solar panel service e.g. to check their system is running correctly
• 20% have been offered a voltage optimiser 
• 19% have been offered a replacement inverter
• 11% have been approached about solar buyback

Based on an online survey of 2,163 Which? members with solar panels in May 2018. 

Some of these product offers can be legitimate and worthwhile - but in some cases they're being mis-sold. Think carefully about the claims made about any product you're being offered, and work out whether it will benefit your system.

Solar panel servicing

Solar panel servicing can include cleaning your panels, electrical testing, inspection and checking the performance of your solar PV, depending on the company offering it.

We've seen quotes from companies for around £200 for a one-off service and cleaning, up to a £495 annual contract also including a breakdown repair and insurance against damage and theft.

Is solar panel servicing necessary?

Solar PV systems require little maintenance besides keeping them relatively clean (rain will do this for you, if your panels are tilted at least 15 degrees) and making sure they're not shaded by trees. You should, however, expect to replace the inverter at some point during the life of your solar panel system (more on this below).

Check the information pack you received when your installation was completed; this should tell you about any maintenance and cleaning your system needs.

The Energy Saving Trust advises to keep an eye on your system and how much electricity it's generating so you know what to expect - and when something might be wrong.

Get the best from your solar panels with solar PV owners' tips.

Solar panel voltage optimisers

Voltage optimisers reduce the electricity voltage coming into your home. Companies claim this can reduce your electricity consumption and save you money on your electricity bills. We've seen claims of 20% electricity bill savings.

However, the Renewable Energy Consumer Code(RECC, which sets out high standards of consumer protection and service expected from the companies it accredits and helps resolve consumer disputes with its members) found no 'objective robust evidence' for these claims when it examined them in 2015.

One study found that voltage optimisers had different impacts in different homes - reducing electricity use in some but increasing it in others.

Is a solar panel voltage optimiser necessary?

Before you purchase a voltage optimiser, you need to calculate carefully if it is likely to reduce your energy bills.

Weigh up the cost of the voltage optimiser, against the savings you are likely to make from it. Potential savings depend on how high your incoming voltage is, the appliances you own (you'll save less if you already have energy-efficient appliances), how much electricity you currently use, and how long the voltage optimiser is expected to last.

Find out more about home energy storage systems.

Replacement inverter for your solar panels

Inverters have a shorter lifespan than solar PV panels, so you'd expect to replace your inverter during the 25 year lifetime of your system. Some 11% have replaced their inverter, according to our research into solar panel problems.

Of the one in five (19%) solar panel owners who were approached by a company offering a replacement inverter, nearly two thirds of these (61%) were told that replacing it would increase the system's performance.

Inverters cost from around £500 to several thousand pounds.

Is a new solar panel inverter necessary?

If your inverter is still working, you don't need to replace it. Some newer inverters are more efficient than old models, but how much benefit you'll see will depend on the inverter you're replacing and how shaded your system is.

If you are tempted by a company's claims, make sure that you understand how it has calculated the savings you'll make. Then weigh up the cost of buying the new inverter against how long it'll take to earn that amount from any extra savings you'll make on your electricity bill as a result of installing it.

Solar buyback

With solar buyback (or solar equity release), companies offer a lump sum to householders who have solar PV installed in exchange for receiving the remainder of your feed-in tariff payments. You continue to use the free electricity generated by your panels.

Some companies state you could 'earn up to £20,000'.

Is solar buyback worth it?

An upfront lump-sum payment may be tempting, compared with waiting for your cash to arrive gradually over the period of your feed-in tariff payments. The actual amount offered is calculated using factors including your FIT rate, how many years you have left to receive it, the size of your solar panel system and your generation meter reading.

Calculate how much you'd expect to receive in feed-in tariff payments during the remainder of your contract, and compare this with any lump sum offers you're made before deciding whether to go ahead.

Read more about free solar panels and solar buyback.

If the company that installed your solar PV has stopped trading

Some consumers have been approached out of the blue by companies offering solar panel products and services after the company which originally installed the solar panels has ceased trading or gone bust.

If you are in this situation, ask the company how it got your contact details. Consider carefully its offers of any add-ons or services, and whether they are necessary.

As with solar panel systems themselves, you should not feel pressurised into signing a contract with a new company without having all the information you need to make the decision. Ideally, you should see clear calculations demonstrating how and add-on will increase the benefit you get from your solar panels, set against its cost.

Check our solar panels sales checklist for tips - including avoiding 'limited time' discounts.

*(Online survey, May 2018: 2,163 Which? members with solar panels)