Solar panels generating but no saving on bills

bannerman · 16 August 2019 at 6:51PM

We had solar panels installed in November 2018. There are fourteen 300W panels facing West with no shading, a Solis 3.6kW inverter and an OptimisePV wireless immersion control.

They were installed as part of the Solar Together scheme from Suffolk County Council. Unfortunately not by a local company.

The panels are working and have generated 2580kWh in this time. The immersion heating works but the hot water gets extremely hot. Average at moment of 3.5kWh going to the immersion heater per day.

However, there has been no savings on the electricity bills. Between January and July this year we have been billed for 2262kWh by British Gas, the previous January to July with no solar panels was 2188kWh. These are actual readings and not estimated bills. During June which I would think would be the best month for solar it was 218kWh this year and 245kWh the previous year but this year we were away for 5 days which accounts for that saving

So could the problem a faulty installation, a faulty inverter, or a faulty meter or something else? The meter is a smart meter which was already there when the panels were installed.

I have contacted the installer numerous time since first noticing the problem in May but they keep ignoring me. "We are looking into this" emails every couple of weeks from their customer services department! Have also spoken to British Gas who can test the meter but will make a charge of £61 if there is no fault in the meter.

KevinG · 16 August 2019 at 7:20PM

If you have a smart meter surely you can see what consumption is being registered at any time. If the sun is shining it should be showing zero assuming you are not running any high-demand items such as a kettle or a cooker. If it isn't that suggests there is a problem. How are you measuring the generation? You are doing well to get 2580 kWh in that time so I don't see how the installation or inverter can be at fault.

legoman62 · 16 August 2019 at 7:50PM

bannerman wrote: »

We had solar panels installed in November 2018. There are fourteen 300W panels facing West with no shading, a Solis 3.6kW inverter and an OptimisePV wireless immersion control.

They were installed as part of the Solar Together scheme from Suffolk County Council. Unfortunately not by a local company.

The panels are working and have generated 2580kWh in this time. The immersion heating works but the hot water gets extremely hot. Average at moment of 3.5kWh going to the immersion heater per day.

However, there has been no savings on the electricity bills. Between January and July this year we have been billed for 2262kWh by British Gas, the previous January to July with no solar panels was 2188kWh. These are actual readings and not estimated bills. During June which I would think would be the best month for solar it was 218kWh this year and 245kWh the previous year but this year we were away for 5 days which accounts for that saving

So could the problem a faulty installation, a faulty inverter, or a faulty meter or something else? The meter is a smart meter which was already there when the panels were installed.

I have contacted the installer numerous time since first noticing the problem in May but they keep ignoring me. "We are looking into this" emails every couple of weeks from their customer services department! Have also spoken to British Gas who can test the meter but will make a charge of £61 if there is no fault in the meter.

Is your wireless immersion controller actually supplying power to the immersion?

Or are you supplying power from the mains supply to heat the immersion heater?

You could always turn the immersion stat down if the water is too hot!

1961Nick · 16 August 2019 at 7:52PM

I’m not sure what you have in place for monitoring, but a simple check is to see what the smart meter is registering when the immersion diverter is working......it should be zero.

There should be enough sunshine tomorrow to test it even if it means reducing the household load a bit to force the divert.

mmmmikey · 16 August 2019 at 8:16PM

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.

Ectophile · 16 August 2019 at 9:01PM

Do you use a lot of electricity during the day? If not, then the solar panels may be saving you very little. It doesn't help if the panels are generating loads of electricity during the day, but you only use electricity in the evening.

Heating a tank of water a day might save you a bit, but not so much if you are heating it to a far higher temperature than you would have before.

Hexane · 16 August 2019 at 11:21PM

Does the OptimisePV thing show what it thinks is being exported, or how much "surplus" power it is using, at any one time? One of the things I like about my Eddi device (which serves the same purpose) is that its front panel display shows me (with kW numbers) what it thinks is surplus being used to heat the water, what it thinks is surplus being exported to the grid, what it thinks is deficit being imported from the grid, and also when it thinks the immersion heater's "max temp" has been reached. (To expand on something legoman62 said, if your immersion heater's "max temp" is so high that your hot water is way too scalding, then most immersion heaters can be adjusted - your local handyman should know how to do this, but mine didn't).

One of my worries when having solar PV installed was that some electricity meters allegedly read export as import, therefore with solar panels installed people would pay more, instead of less. When was your meter installed? Is it a smart meter? Do you have the time and patience to watch it for a decent amount of time on a sunny day when you have no appliances running?

If you don't already have a smart meter installed, I do wonder if some electricity supplier might be one of those that is eager for you to have one installed (at no cost to you), this would remove the meter as the possible cause of the problem, without paying the £61. Although, always mention that you have solar panels, and ask for assurances that it will work correctly, before any such meter replacement takes place.

Martyn1981 · 17 August 2019 at 8:11AM

Hexane wrote: »

One of my worries when having solar PV installed was that some electricity meters allegedly read export as import, therefore with solar panels installed people would pay more, instead of less. When was your meter installed? Is it a smart meter? Do you have the time and patience to watch it for a decent amount of time on a sunny day when you have no appliances running?

I was wondering that, seems to happen with some Siemens meters (see PV FAQ's section 4a) but does it happen with some smart meters .... no idea?

Hopefully the smart meter can give import and export figures to help a bit with what's going on.

mmmmikey · 17 August 2019 at 9:43AM

Picking up on the point re: smart meters and readings, are the readings given in the OP readings from the meter itself or from the associated in house display? There is a scenario (which I believe used to be the case with EDF some time ago) where the meter itself deals with imports and exports properly but the in house energy montior / display didn't, so this is something else to check.

bannerman · 17 August 2019 at 5:09PM

Thank you for your replies.

If you have a smart meter surely you can see what consumption is being registered at any time. If the sun is shining it should be showing zero assuming you are not running any high-demand items such as a kettle or a cooker. If it isn't that suggests there is a problem. How are you measuring the generation? You are doing well to get 2580 kWh in that time so I don't see how the installation or inverter can be at fault.

Generation is measured using an app which is showing same as the generation meter. Usage is measured on the British Gas app/online account but that does not show actual usage for about 2 days.

Is your wireless immersion controller actually supplying power to the immersion?

Or are you supplying power from the mains supply to heat the immersion heater?

You could always turn the immersion stat down if the water is too hot!

Wireless immersion controller is supplying power to immersion and the stat is turned right down. I think this might be that the heater is at the top of the tank and the stat is at the bottom

Do you use a lot of electricity during the day? If not, then the solar panels may be saving you very little. It doesn't help if the panels are generating loads of electricity during the day, but you only use electricity in the evening.

As a retired couple we are able to use most of our electricity during the day for cooking, washing, drying, dishwashing. Since having solar have been conscious of what is switched on and not running tumble dryer at same time as cooker etc. This is one of the main reasons I was surprised that there is no saving on the electricity used.

Does the OptimisePV thing show what it thinks is being exported

It shows what it has "saved" during the day, week, month but no other useful information

One of my worries when having solar PV installed was that some electricity meters allegedly read export as import, therefore with solar panels installed people would pay more, instead of less. When was your meter installed? Is it a smart meter? Do you have the time and patience to watch it for a decent amount of time on a sunny day when you have no appliances running?

The smart meter was installed about 3 years ago, on a sunny day it does show export. It is a Landis+Gyr E470 meter. Do you think it is worth getting it tested or could I get it changed by switching supplier

So my main concern is that we are generating a good amount of electricity and using some of it to heat the immersion heater where is the rest going?

The salesman suggested a payback time of 8 years which I did not believe, I was hoping for maybe 12 years but with the FIT payments at about £200 for the year and the saving on gas by not using it to heat water in the summer looks like payback could be 25 years.

legoman62 · 17 August 2019 at 5:22PM

Your Quote:-
"Wireless immersion controller is supplying power to immersion and the stat is turned right down. I think this might be that the heater is at the top of the tank and the stat is at the bottom"

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

My immersion has a stat in the top that I keep high.
I keep my boiler stat temperature lower so that it rarely cuts in:D

Solar panels generating but no saving on bills

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