Upgrade to existing 2011 solar panel system? 17 December 2020 at 10:42AM in Green & ethical MoneySaving 18 replies 278 views

pip895

We are the lucky owners of a 9 year old system split between SSE and WSW roof.  The larger array is on the WSW roof and has issues with shading from a chimney.  Having said that the system has been great and paid for itself compliantly last year.  

What are you allowed to do with an existing system - presumably not replace the panels with more efficient ones, but can you fit something like solar edge to reduce the effect of the shading?

On a separate note we are relatively heavy power users with an EV and heat pumps Koi pond etc so use the great majority of the energy produced.  However we are assumed to export 50% as we don’t have a smart meter.  Would we loose out on the assumed export if the metre was upgraded? We do like the idea of charging the car via octopus agile or the like but economically it might not make much sense..

Martyn1981

Hiya, you will need to check with your FiT provider, and if they are your leccy supplier, whether their smart meters are used to calculate export - note, they may measure export, but that doesn't mean they will necessarily use that figure instead of the deemed export.
You can add more panels to your existing system, and even replace panels with more efficient ones, but you'll need to advise the FiT provider (and double check this first before you do anything), and they will then apportion FiT's in the ratio of the original system to the new total. For instance if you have a 4kWp system and add 2kWp more, then they will pay FiT's on the ratio of 4/6ths of what you generate.
You can upgrade to Solaredge under the existing FiT's as you aren't changing the panels, so it's akin to replacing an old or failed inverter with a more efficient modern one, and also something that could have been in place from day one without affecting the subsidy.
Hope that helps.

Hexane

I've had a smart meter since before my solar panels install (around two years ago). Although it's long been trailed as being policy that deemed export will eventually be a thing of the past, that change hasn't happened here yet and there's no sign of it happening. My view has always been that "eventually" is a very long eventually and the various parties involved have far more other things to fix or implement that are further up their priority lists and they're struggling with.

So for example Scottish Power still can't work out how to implement a website that shows me gas and electricity usage over time based on my smart meter data (which is supposed to be sent daily), they still can't access daily smart meter data to resolve billing issues when I phone them up (asking me to go outside to manually check the meter instead and insisting the meter only sends data quarterly), they still can't work out how to send someone to check or inspect my generation meter which they're supposed to do on a regular basis, last time I checked they still couldn't accept generation meter readings on the tariff change date despite gleefully telling me that this was possible. And then there's the vastly expensive and vastly delayed and shoddily justified smart meter rollout itself. And the government's constant fiddling with what the energy companies are allowed to do, in order to promote an impression of fairness. And the electrification of transport and heating, and the supposedly imminent arrival of the smart self-balancing grid to make it all possible. 

mickyduck55

My electricity is supplied by Octopus and FIT by Eon so I'm guessing Eon have no idea what my export is.. I don't mind either way. I have recently had a battery system installed so in fairness I would be happy to only be paid on actual export.  After saying that for the almost 10 years that I have had my panels I have exported way in excess of what I have been paid for.  I was working full time in London so out of the house for at least 12 hours of generation every day.  In winter 5 days a week would export probably 50 % because of my base load.. the other 9 months of the year I would export 70-80 %... 5 days a week and plenty at the weekends. 

Pile_o_stone

If you are adding some more panels then don't connect them to your existing system, just connect them to a new, second inverter. This means your existing Feed in tariff would be unchanged. Your new panels won't be earning any FIT or export payments but as you're a heavy user, it won't be an issue.
You can add solar optimisers to an existing system without impacting your current FIT payments. Instead of fitting solar edge and having to replace your inverter you could look at TIGO optimisers which work with most inverters and you only need to add them to the panels that are actually in shade.

Solarchaser

I've had a smart meter for just shy of 4 years, been on deemed export for 6.
No issues there.

If you have an old spinny meter though, you will lose the fact that it spins backwards when solar panels are doing their thing.

However charging the car on 5p rather than 15p for the last 2 months has been great

pinnks

I would ask why you want to update anything and why you think you would get a return on that investment? If it ain't broke and all that...
I have a shading issue on my smaller system which "costs" me about 3kWh per day on good sunny, summer days.  If you are really generous and say that I lose that amount on 150 days that is only 450kWh per year.  At 18p (total FiT rates for that system) that is about £80 per year.  The cost of installing anything to combat the shading would be massive - scaffolding, micro inverters or similar, new inverter and labour.  Seems unlikely that I would come in under £1,000, maybe more, so the ROI is 12 plus years, by which time the inverter might need replacing again, and so on.  I decided to just live with the "mistake" I made when doing the original install.   

EricMears

I'd tend to agree with pinnks that it's probably not worthwhile but thought that possibly pip895 might have other works on his roof planned (e.g. replacing some tiles or fitting a Velux window nearby might mean some panels need to be moved or removed temporarily and scaffolding would be in place anyway.  If so,  it was a serious question and deserves a serious answer.

So,  providing original panels (or replacement ones that FIT payer agrees are equivalent) remain,  almost anything else can be added - e.g. Solar Edge, more efficient inverter, heavier duty cabling etc etc.  But don't take risk of adding new panels to same inverter as old : FIT payer's apportionment of new/old split probably won't agree with your own !  A completely separate system with its own generation meter is by far the best route.

mickyduck55

Solarchaser said:

I've had a smart meter for just shy of 4 years, been on deemed export for 6.
No issues there.

If you have an old spinny meter though, you will lose the fact that it spins backwards when solar panels are doing their thing.

However charging the car on 5p rather than 15p for the last 2 months has been great

I thought the spinny back meters were illegal... wish I had one LOL

pip895

I wish we had the potential problem of wheels spinning backward lol.  I doubt we ever get close - meter is more modern anyway.  

We might get away without scaffolding or at least with very little as the problem panels are above a balcony.  I think the original installers just used a section of tower scaffolding. If we were just adding TIGO optimisers to a couple of panels would we need to inform anyone?
We have been toying with getting a new array fitted + a battery but there is no room on the roof so we would be looking at a set in the paddock- not sure how practical that would be though.. We might try and get some quotes for doing both sets of work and see if it all makes sense.

EricMears

mickyduck55 said:

I thought the spinny back meters were illegal... wish I had one LOL

Some 'spinning wheel' meters had some form of ratchet to stop readings reducing.  Older models probably didn't and even those that had them might fail..

They're not actually "illegal" and it's the owners responsibility (not customer's) to detect and swap any that act that way.  No doubt it's terrific fun trying to decide what a fair correction would be.