Solar panel savings now more accurateWhich? campaign leads to better solar panel rules

12 February 2013

Solar panels

If you're considering installing solar panels, the quotes you'll get for how long it will take for the savings to justify the cost will now be more accurate, thanks to Which? campaigning.

The Microgeneration Certification Scheme (MCS), a scheme which certifies installers of solar panels, has changed its rules on how the amount of electricity generated by solar panels should be calculated. 

This means that companies who are part of its scheme will now provide more accurate estimates of how much money you will make from a solar panel system and how long it will take for the system to pay for itself.

You can find expert tips on how to choose, buy and install solar panels in our solar panels guide.

Solar panel investigation

When Which? went undercover to investigate solar panel installers in July 2011, we found that eight out of the 12 companies we investigated underestimated the time it would take for the system to pay for itself. 

This was mainly because the method the companies had to use to estimate payback and savings was flawed and could lead to inaccurate predictions. 

Which? therefore campaigned on this issue and asked the MCS to change its rules.

Flawed solar panel calculations

One problem with the previous standard was that the calculation of how much power the solar panels will generate assumed every house was in Sheffield. But a house in the South East of England won't receive the same sun radiation over a year as a house in Sheffield or in Scotland.

This assumption has now been changed in the new standard and uses geographical zones to give more accurate and bespoke power output estimates for the solar panel system.

Another change we called for, and that has now been made, is to ensure that the effect of possible shade on the panels is properly accounted for and that installers follow a strict procedure to evaluate it. 

Better solar panel quotes

This all means that consumers should get more accurate estimates of how much power their solar PV system is likely to generate and how much money they will make from solar PV panels.

If you are getting quotes for solar panels in the future, make sure you use an MCS certified installer.

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