Solar panels generating but no saving on bills

bannerman

Is the stat at the bottom a boiler stat linked to the C.H.?

No it is not connected to the Central Heating and have turned the gas boiler water heating off during summer, sometimes on days when the sun does not shine have turned the boiler on for an hour to heat the water.

bannerman

Hi - worth keeping in mind that last year we had a record breaking heatwave and this year we had a late start to summer - I was still heating into the beginning of June. So comparing last year and this may not be valid.

I am comparing 7 months last year when we did not have solar panels with the same 7 months this year when we did. Although we had a cold start to summer this year we did not get the 'Beast from the East' which we had the previous year so they probably cancel each other out.

Is it possible that the system has been wired incorrectly so that all the power generated is exported instead of being used in the house?

mmmmikey

Hi


In order to test everything out, could I suggest you do a controlled test yourself as follows? I hope I'm not being patronising here, it's very difficult to know from these forums how techie folk are, so please accept my apologies if this sounds a bit simplistic



You will need to find an appliance with a rating of about 1kW - an electric convector heater would be perfect, it needs to be something you can leave on for about 15 minutes while you do the test. The rating isn't critical, it just needs to be there or there abouts. You should do the test on a sunny day when you think the panels will be generating continually. The test will involve switching off power to most of your house, hopefully you have a co-operative family What you want to find is somewhere you can plug the appliance in where you know it's the only thing on. In my case, I would switch off everything at the breakers at the main fuse boc, except the garage, and plug the heater in there, but what you do will depend on your own house.


1. Plug the appliance in ready.
2. Switch everything else off.
3. Take a reading from the generation meter and supply meter.
4. Wait 15 minutes and take readings again, and work out the difference between before and after. The supply meter show show the same amount of export as the generation meter. If the supply meter shows import and export separately, there should be no import.

5. Now repeat this but with the heater on, again taking before and after readings . The supply meter should now show less export than the generation meter. Again, there should be no import.


(I'm assuminging that your meters show a couple of digits after the decimal point, if not then you'd have to do this for a longer period)


If you can try this and then post your figures back, we should be able to work out between us if all is working OK. Hope this all makes sense, and again sorry if this sounds a bit basic or patronising, that isn't my intention.


Hope this helps, Mike

markin

If your water is over 60c you should have a plumber fit a thermal mixing valve, it mixes cold water into the pipes so all taps are at a safe temp.

https://www.screwfix.com/c/heating-plumbing/t-static-mixing-valves/cat831694


Have you measured how much gas saving you have made? Or do you turn it off every summer.


How many KW is the system? The immersion control starts at 70W

Martyn1981

bannerman wrote: »

Is it possible that the system has been wired incorrectly so that all the power generated is exported instead of being used in the house?

I've heard of that once, where the PV connection was made to the wrong side of the import meter. TBH that's an astonishingly stupid thing to do.

Just check that the feed from the TGM (total generation meter) is then going to the CU (consumer unit). If it is, then it will be used by the house and excess exported.

Is there any chance that something new has been added that has increased your demand by a significant amount? Any chance that you have an old freezer that is faulty and cycling constantly, as that can result in a vast increase in leccy consumption?

I'm not trying to be difficult, I totally agree that you should have expected to see a noticeable difference, just trying to remove any other explanations.

For comparison, we generate approx 4,500kWhs per year, and our import dropped from 3,000 to 1,500.

EricMears

Martyn1981 wrote: »

I've heard of that once, where the PV connection was made to the wrong side of the import meter. TBH that's an astonishingly stupid thing to do.

It would of course have been illegal to interfere with any cable(s) on the supply side of the import meter !

bannerman

In order to test everything out, could I suggest you do a controlled test yourself as follows? I hope I'm not being patronising here, it's very difficult to know from these forums how techie folk are, so please accept my apologies if this sounds a bit simplistic

Thanks for this suggestion, not patronising at all, I will try this in next couple of days

If your water is over 60c you should have a plumber fit a thermal mixing valve, it mixes cold water into the pipes so all taps are at a safe temp.

That is a good idea, seems odd that the immersion heater and hot water outlet are on top of the tank with the thermostat and cold feed on the bottom so hopefully that should solve that problem.

Just check that the feed from the TGM (total generation meter) is then going to the CU (consumer unit). If it is, then it will be used by the house and excess exported.

Yes it goes to a consumer unit. We do have 2 consumer units, one of them is in an annexe which is also where the smart meter is located. The TGM is wired into the 2nd of the consumer units in an airing cupboard in main part of the house. I did point this out to the surveyor and the electrician when they fitted the panels.

I only suspect faulty wiring because I had no confidence in the electrician who installed it. He had driven from Merseyside to Suffolk, arrived 2 hours late having been stuck in traffic, and then rushed everything to get to the next installation in the afternoon.

For comparison, we generate approx 4,500kWhs per year, and our import dropped from 3,000 to 1,500.

That is the sort of figures I was expecting, and we have not added any extra large appliances.

joefizz

Reads to me like your immersion diverter might be faulty or thermostat or something, which is resulting in all your pv output being diverted to the immersion.


Disconnect this (or pull the fuse/circuit breaker on the immersion, it should be separate with a cut off isolation switch) and see if that makes any difference.


Leave this out and do mikes test.

Its the first thing I would look at, particularly if your water is hot, dont assume your thermostat, diverter, measurement loop is working, or a combination of those might be failing.

Martyn1981

bannerman wrote: »

We do have 2 consumer units, one of them is in an annexe which is also where the smart meter is located. The TGM is wired into the 2nd of the consumer units in an airing cupboard in main part of the house. I did point this out to the surveyor and the electrician when they fitted the panels.

OK, I'm going to ask a really stupid question now, and it's for everyone.

I've just looked at my set-up as I also have a second CU, the classic 'garage board' installed recently. The PV however (both feeds) go into the original CU.

Now, the main power comes in, it goes through the big breaker (mine's a 100A unit), then goes to the import meter, then to two blocks, which I think are called 'Henley Blocks'(?) with a feed then going off to each of the CU's.

Now, whilst my PV isn't on the new board, if it was, is there any way for it to avoid my old CU, and the vast majority of my household consumption and instead 'sneak out' the house?

I'm assuming this is complete and utter gibberish and that in such a situation the leccy would flow from the Henley Blocks to the CU asking for power, but I figured I'd throw myself in front of the bus, and ask the daftest question(s) just to clear up any possibilities. Or if by accident I've raised some related mis-wiring issue that could have happened.

mmmmikey

Martyn1981 wrote: »

OK, I'm going to ask a really stupid question now, and it's for everyone.

I've just looked at my set-up as I also have a second CU, the classic 'garage board' installed recently. The PV however (both feeds) go into the original CU.

Now, the main power comes in, it goes through the big breaker (mine's a 100A unit), then goes to the import meter, then to two blocks, which I think are called 'Henley Blocks'(?) with a feed then going off to each of the CU's.

Now, whilst my PV isn't on the new board, if it was, is there any way for it to avoid my old CU, and the vast majority of my household consumption and instead 'sneak out' the house?

I'm assuming this is complete and utter gibberish and that in such a situation the leccy would flow from the Henley Blocks to the CU asking for power, but I figured I'd throw myself in front of the bus, and ask the daftest question(s) just to clear up any possibilities. Or if by accident I've raised some related mis-wiring issue that could have happened.

Not a stupid question of you don't know the answer - none of us are born as electricians


Simple answer is everything as it should be.