Adding solar panels to an existing system.

[graduate_owner]

Hi all, looking for information on solar panels.

We have a 4kW solar panel system which was installed about 13 years ago and so qualifies for FIT payments. I would like to add more panels now, which will not qualify for FIT payments, plus battery storage. I don't want to jeopardise my entitlement to FITs as they are worth around £3000 a year overall now. Is it possible to have another 4kW system alongside the existing one without major issues? Could a battery be used to store energy from both sets of panels? Could both sets of panels be integraded into the existing house mains? I have contacted my DNO and they said I could expand my system without problems.

Any advice would be appreciated.

K

 

[Eshmiel]

Hello Grad,

Yes, you can do as you want - preserving your FiT arrangement whilst adding another array of solar panels, batteries etc. There are some limits and things to watch out for .....

The FiT system needs to remain distinct from any new solar and so forth so that it behaves just as it did before new stuff was added. This means that you shouldn't connect any batteries to it as this would allow you to use batteries to gather more solar from your new panels then export it via your FiT inverter. That would break and cancel your FiT agreement.

You can change your inverter that serves your FiT solar panels (they tend to have a life of only around 12 years) but you can't change or add to your solar generation equipment that is covered by the FiT agreement without breaking and losing it. In most Fit agreements, you can't even change the solar panels for different panels.

You'll probably also have excess solar from your new panels that you export to the grid if you can't use it in the house or get anymore into your batteries because they're full. You can't come to an arrangement to sell that excess solar without, again, breaking and losing your FiT agreement. You have to give it to the grid for nowt. Get an e-car to put it in instead.

Some areas have a grid infrastructure that isn't very capacious. Until recently that meant that proposals for additional solar panels that might also export to the grid (in addition to your FiT export) were sometimes refused on a "grid can't cope" basis. However, there's now a new inverter standard (G100) that allows the grid operator to prevent any excess export from that new inverter if the grid is being overloaded by exports. This means you can have more solar panels as long as they operate through such a G100 inverter.

Hope this helps.