Solar panel/ battery advice

Ajco123

I have 16 solar panels and 1 battery. We have a water tank and boiler . As I understand it our solar panels have a solar boost box which is connected to our emersion switch and our water tank. This enables us to heat our water via the panels. So therefore we are not using our boiler system to heat our water. However we need to keep the emersion switch on constantly.  My question,  is this the most economical way . I ask because my monthly bills are £220 which is more than my current neighbouring house ( same size / people ) although they have a combi boiler . My yearly cost are 2,700. We do recieve around £800 back regarding fit payments? . Thanks 

Netexporter

Solar diverters are going out of fashion. You can earn more exporting your solar than it costs to heat the water on an off-peak rate. You just need a smart meter to be able to access.

Heedtheadvice

....and fitting a smart meter means that you are not eligible for FIT so you need to work out if that would be better for you.

It could be that having you immersion switch on all the time means that you are buying expensive electricity at the times when your solar or battery is not providing the water heating  power. That will be a very expensive situation if you need another of hot water a d switched on 24 hours.

If you space heat generally from your gas (?) boiler - you do not say what type it is- then that is likely to be cheapest and around a similar cost to the better low cost import and export tariffs.

However much depends upon things like time of year ( generated Solar power) how your diverter works and how it interacts with your battery and the capacity of the latter and how your battery inverter works/ is set up and your needs.

It is most likely that you could  generate/ store enough electricity for your needs in late spring through to early autumn but will almost certainly not meet your needs in  winter.

Without  lots of figures of what you consume and store and generate and your Fit rate, at best, we  an only make general guesses. Suggest providing lots more data?

I am in a broadly similar position to you. I could get  better value on the electricity front by fitting a smart meter and the better tariffs for electricity but then risks losing FIT/deemed export - which income is guaranteed and increases with inflation for some time to come.   EDIT[ The 50% deemed export payment is the loss see posts below]

I maybe do not have the best setup I admit but heat water and space fairly cheaply in gas in the colder months ( much less in summer), store PV to time shift electricity,  charge a hybrid car, mildly heat a greenhouse in spring, top up via diverter/immersion any excess etc. The diverter has paid for itself over the years but now (' out of fashion ') is used less frequently but not owing to the latest tariffs but less need over the whole year.

I am quite a heavy user of electricity even not being my main heating ( over 4500kWh per annum ) but I only purchase about 1500 ( under £50 per month ). On top of that is gas at 1200kWh.

You are right to ask the question but we need to know your aim ( financial or green or  combination) and your specific data. Could well be you would be best to abandon FIT and go for smart meter/SEG but nobody can be certain at this stage of information.

Alnat1

You need to think about what temperature is the tank being heated to and could that be lowered? Ours is set to 55C on the tank thermostat and that's great for a hot shower.

How much hot water do you actually use? If you have a family all wanting baths/showers every day and manually wash dishes then the tank might need to be reheated a lot. If only 1 or 2 people who mostly have a shower and you have a dishwasher, then heating it for just an hour a day (possibly with gas) will definitely save you money. Our tank is only on for 40 minutes and uses around 4kWh of gas, plenty for our 2 showers and some left over to fill a mop bucket etc.

It's possible to keep the generation payments for FIT (larger payment) but give up the 50% deemed export and go with metered export, you can get 15p/kWh for that and it could work out better for you. You need to do the maths

paul991

Fitting a smart meter does not mean you can not still get  FIT , But  you can change the deemed 50 % export to another tariff if it suits you ,as my house is occupied during the daytime there is little advantage in it to me .If you are a high user you should working out what is causing it.   If you do change the deemed export amount you can not change back later. 

Screwdriva

I would not use immersion electric heating for hot water unless you are on FIT or lack any other option other than oil (for environmental/ ethical/ convenience reasons). If you are on FIT then it warrants a closer look, as does a battery.

I have not been able to find a more economical way to heat hot water that bests a Mixergy iHP heat pump cylinder on running costs.

Heedtheadvice

paul991 said:

Fitting a smart meter does not mean you can not still get  FIT , But  you can change the deemed 50 % export to another tariff if it suits you ,as my house is occupied during the daytime there is little advantage in it to me .If you are a high user you should working out what is causing it.   If you do change the deemed export amount you can not change back later. 

Quite. I did not have it fully correct!

For reference from OFGEM:

"What is the Smart Export Guarantee (SEG) and can I apply for it even if I’m a FIT generator?

The Smart Export Guarantee (SEG) requires electricity suppliers to pay small-scale generators for low-carbon electricity which they export to the grid. SEG Licensees determine the rate which they will pay SEG Generators, the contract length and other terms, but the tariff rate must always be above zero.

Most accredited FIT installations will be eligible for the SEG, provided they have a smart or export meter installed. However, you cannot receive both SEG payments and FIT export payments for the same electricity. In order to register for the SEG, you must first opt out of FIT export payments for their installation by contacting your FIT Licensee."

Points to consider; deemed export on FIT ( for the later Installations only I understand ) is guaranteed for 50% of the generation.

SEG rate for the actual export power  is subject to the contract with the Licensee so the rate ( that can be better than the deemed export rate ) is not fixed just must be more than zero.

If you use a lot of your own generation you might also loose out compared to the 50% deemed export.

The use of batteries can help a great deal in these respects buying cheap selling at higher rates.

As far as I am aware ( hopefully someone will correct if not the case) there is potentially more risk with SEG than with FIT. So choice is worthy of careful consideration

Alnat1

What is the FIT rate for your deemed export? It changes, depending on when the system was fitted.

paul991

2014 ,6.79 p then half it

theboylard

Ajco123 said:

I have 16 solar panels and 1 battery. We have a water tank and boiler . As I understand it our solar panels have a solar boost box which is connected to our emersion switch and our water tank. This enables us to heat our water via the panels. So therefore we are not using our boiler system to heat our water. However we need to keep the emersion switch on constantly.  My question,  is this the most economical way . I ask because my monthly bills are £220 which is more than my current neighbouring house ( same size / people ) although they have a combi boiler . My yearly cost are 2,700. We do recieve around £800 back regarding fit payments? . Thanks 

We've got a solarimmersion diverter, been running for 10 years now so lots of free hot water spring to autumn.

If it was installed correctly, then it should only be diverting the solar export to the immersion heater. Ours is switched on permanently, but we have a switched fused spur with light that lights up when heating with solar.

However, since adding an ac side 2nd inverter and batteries, I'm going to disable the diverter.

If you have a smart meter, check that your FiT provider doesn't need to be informed.

Good Energy have recently advised that if you have a smart meter, then you can no longer be paid for export via deeming. You must inform them, they will apply for an export MPAN, then you will be paid for the actual export.

Good Energy do pay 15p/kWh for export, so it's not all bad.

Solarchaser

I had my fit with edf, they also fitted a smart meter, and fit was unaffected. 
I left edf and went to bulb, fit unaffected.
I then went to octopus who had to fit a different smart meter, fit unaffected. 

However I have now contacted them to move to seg for the export portion of fit as the 15p rate they are paying makes for an attractive proposition, vs the deemed 3.5p part of the fit.

Also a 2014 installation. 
The majority of the fit is generation based rather than export.