[athers71]

Hi, we moved to this house 2 years ago and inherited a 4kWh PV system and a FIT that started in August 2013.

Our FIT statement 1/12/2023 stated:

Energy generated 365.00 kWh @ 21.73 p/kWh. £79.31

Energy exported 182.50 kWh @ 6.79 p/kWh

£12.39

So we received £91.70.

Next to the Energy export it says (deemed 50%).

Our electricity charges, including standing charges and Vat etc for the past 12 months were £1,128 and we received £604 in FIT payments, so just over 50% of our consumption.

I have a couple of questions...

1) Is our electricity bill net of what we generate and use? or are will billed gross?
2) Is that 50% export amount fixed or can it be changed - is it likely to be better?
3) Am I making the best use of the PV panels? Should I have a battery? Can I or should I leave FIT if there are better options available?

Apologies there is a quite a lot there, but its been on my mind for ages!

[retrotecchie]

@athers71

1. Your electricity bill and your earnings from FiT are completely separate. You are billed gross for what you use.

2. Your deemed split can only be adjusted by having the system recertified. Not worth the hassle or the expense and you are more likely to lose out.

3. You will make best use of your system if you use energy when the sun is shining. You can export a unit of solar for 6.79p but by not having to import a unit at 29p or thereabouts, you will be saving money. A battery will help if you use the majority of your energy at night.

[athers71]

Originally Posted by retrotecchie

@athers71

1. Your electricity bill and your earnings from FiT are completely separate. You are billed gross for what you use.

2. Your deemed split can only be adjusted by having the system recertified. Not worth the hassle or the expense and you are more likely to lose out.

3. You will make best use of your system if you use energy when the sun is shining. You can export a unit of solar for 6.79p but by not having to import a unit at 29p or thereabouts, you will be saving money. A battery will help if you use the majority of your energy at night.

Thanks for the very quick response. So in respect of point 3, our peak usage will depend on the time of year and what day of the week it is. So without any battery storage, whilst we do get paid for everything we generate, some of that energy will be lost if we don't have a demand for it at that moment. So if we captured all our energy generated to battery, and then used it in the evenings, would that be more efficient and economical?

[athers71]

That's made me go and look at my annual generation, so around 2,500 kWh in each of the past 2 years. I don't have any historic data from previous owner. I'm 150 degrees SE facing but in the North West, clear line of sight though! That seems to be well below the "3,400 kWh" the average 4kWh system generates in the UK. Does that feel right or do I need to get my system/panels checked?

I generate less than I consume, so perhaps a battery may be a good idea!?

[retrotecchie]

@athers71

Unless your panels are facing due south and you live in Cornwall, 2500kWh sounds reasonable for a 4kWp system at your location.

A battery will possibly help maximise your system performance but will be expensive. You'll need to figure out whether the investment pays back over a couple of years.

I use my solar as it's generated as I tend to use most of my power by day but my 800Wh battery gives me a bit of storage for occasional nighttime use. My solar is completely standalone so I don't have FiT or SEG but has paid for itself in around 7 months on my energy savings, so every watt now is pure profit.

[wizzo227]

2500 kWh per year from a 4 kW(peak) system seems a bit down on expected for 150 degrees SE facing, unless you live somewhere as cloudy as Clitheroe. 3800 kWh per year is par this far South; anything less must be for a reason. Is it mucky enough on the roof to want to call a window-cleaner with a tall ladder ? Are there obvious not-quite-rights such as too many stacked boxes obstructing cooling air near to the inverter in the attic ? Don't buy more things until you've found out why your rooftop generation is underperforming.

[wizzo227]

Did you find a reason why your free locally generated solar electricity might be making less for you than your 4kW rooftop ought to be capable of ?

[Lee_EONNext]

@athers71 Your estimated Generation will be based on the Total Installed Capacity, this figure should be on the MCS certificate that relates to the system.

Solar Generation does depreciate over time, however there are so many factors to generation and it's amount, for me personally and given my experience I would expect a 4kw system to generate more than 2500 units, however again, the weather, are the panels covered by anything, dirt etc, how's the weather realistically been etc.

Not that I'm an installer but I've seen things effect generation such as a faulty inverter or one of the panels is not doing what it's meant to etc, again in my experience we seem to see these being changed around the 7-10 year mark. It could just be this is what your system is generating what it's expected too.

Do you have the MCS certificate? The certificate will have the estimated annual generation (EAG) and the installer details, the installer would probably be the best person to speak to, if you wanted the system checked over?

If the installer is no longer trading, any MCS accredited installer can check your system over.

If you don't have the document pop me a DM, I will see what I can do 🙂