Anyone using battery back up stystems with solar?

[agricrop]

Hello
As a result of high quote to upgrade my transformer for anything over 11kw I have been looking at ways to get around upgrading my transformer. I have stumbled across a company which can install a 50kw-100kw roof mounted solar system and only export 11kw to the grid using special inverters, large battery backups and electricity dumping devices.
Has anyone got a system like this? Is it really feasible to receive say 100kw of feed in tariff with a system of this type while only exporting 11kw? My DNO is with SP energy networks if that helps.
I'm a little sceptical as it sounds too good to be true.

Thanks, Agricrop

 

[Exfarmer]

You cannot receive FIT payments for dumped electricity.
However it should be possible to claim for power stored and used later.
However are you really sure that the economics stack up? A storage battery of this size is going to be very expensive and what is it's working life!.
Remember your max production will be in the summer, your use presumably will be higher in winter.
Normally an 11kw connection will give a max feedback of 8kw that is an absolute max feedback of 192 Kwh a day, my 50 Kw install maxed at 562 last year and I have heard some appreciably higher. You are going to be storing a phenomenal amount of power for a long. Time.
An average tractor battery is 7-8 kWh

 

[agricrop]

Thanks for your reply. The idea was the batteries would run my refrigeration units at night. Figure wise, I had a salesman / company owner round yesterday who hasn't yet given me any figures. He wanted to put a usage metre on farm to work out the cost of a "custom built battery system first" This would cost £500.
I found this battery back up system supplier in the energy now magazine.

 

[Exfarmer]

To check your usage at night turn, just check your meter last thing and first thing divide by hours to find out hourly consumption.
I would suggest if you have a fairly constant demand such as Fridges firstly check if you can install a day night meter.
This should slash the night running cost
Then look at the maximum install you can have, I guess you are single phase so it would be about 8 KW.
If you are using a constant 8 kw for your fridges the payback will be very good as you will not only get your FIT , reduced energy bills but also be credited with 50% Export.
such a system should not cost much more than £9K
You will Earn about £970 per annum in FIT
assuming you use 80%, quite easy when matched to something like a fridge plant running continuously and you are paying 12P a unit. This will save £768 in reduced bills
and you will also earn a further 4000 X .048= £192 in presumed export
total £1930 per year
I reckon this is equivalent to about 22% on your capital.
you can also choose to call the install domestic and not pay tax on the income but you would not be able to reclaim the VAT

 

[mikelaluz]

Thanks for your reply. The idea was the batteries would run my refrigeration units at night. Figure wise, I had a salesman / company owner round yesterday who hasn't yet given me any figures. He wanted to put a usage metre on farm to work out the cost of a "custom built battery system first" This would cost £500.
I found this battery back up system supplier in the energy now magazine.

Hi Agricrop

As Exfarmer says it's pretty straightforward to work out usage figures and I'm not really sure where the £500 meter comes in.

The system your supplier is referring seems to be a mix between EMMA (Energy Micro Generator MAnager) and Battery Storage. And if this is the case why would you want to dump excess generation if you have battery storage?

Your initial premise of generating say 50 kWp and only exporting 11 kWp is now feesible with the use of simple smart switching which costs approx £250 and is supported by all of the DNO's. But it's very much down to the costs v returns - If you are a low day time user then you will receive reduced FIT and very little Export Tariff so this is really aimed at high users.

Please feel free to give me a call and I'll be happy to work out the figures for you

Kind Regards

Mike Smith

 

[agricrop]

I guess you are single phase so it would be about 8 KW.

Sorry I'm three phase. A small system of say 15kw would pay back in 5 years although wouldn't make much of a dent in my electric bill hence looking for a 100kw system.
A 100kw system would pay back in 7-8 years with the added cost of the DNO.
A 5O kw system would take 9-10 years so is a non starter.

 

[mikelaluz]

Hi Agricrop

What is your monthly usage or cost ?

 

[agricrop]

Hi Agricrop

And if this is the case why would you want to dump excess generation if you have battery storage?

Where would the power go once the batteries are full and only 11kw going to the grid at times when I have a low power usage?
My problem is I have a high peak power usage. It can be all or nothing.

 

[agricrop]

Hi Agricrop

What is your monthly usage or cost ?

Good question. Predicted usage is only £750 odd a month. However I have built a cold store since so I'm waiting for a nice surprise in my next electric bill as the meter is way out.

 

[mikelaluz]

Without analysing your usage it will be impossible to tell. But my guess is that battery and EMMA will be a fairly costly job.

If you are in Shropshire it's unfortunate you're not with Western Power their current upgrade costs seem to be very low in comparison to other DNO's

 

[mikelaluz]

Good question. Predicted usage is only £750 odd a month. However I have built a cold store since so I'm waiting for a nice surprise in my next electric bill as the meter is way out.

You need to look at the monthly splits of usage against monthly generation.

A 50 kWp system in Shropshire for round figures will produce 45,000 KwH's per year which at 10p per unit (electricity cost) saves £4,500 per year if you were able to use it all but of course the peaks and troughs of generation mean you produce the majority in the summer months which may or may not suit your business.

The file attached shows the monthly generation figures for a farm in Bristol but it will give you something to measure your monthly usage against (they are looking at about 50,000 kWh's)

 

[Exfarmer]

I am not selling anything, so have nothing to gain. I am unsure how a 100kwsystem can possibly pay back quicker than a 50 unless you are using a huge amount of power, which you cannot be as you have not got the input to balance.
With your current supplier quoting to charge £500 for a meter you do not need I would seriously question his credentials.
Without knowing more details it is difficult to say more

 

[agricrop]

I am not selling anything, so have nothing to gain. I am unsure how a 100kwsystem can possibly pay back quicker than a 50 unless you are using a huge amount of power, which you cannot be as you have not got the input to balance.
With your current supplier quoting to charge £500 for a meter you do not need I would seriously question his credentials.
Without knowing more details it is difficult to say more

Simply the 100kw system will pay back quicker than the 50kw system due to the DNO upgrade cost of over £50k being the same for either system. Therefore the cost is spread over double the kw.

The £500 tempory meter charge was to see what I was using also made me a little cautious. Apparently I would get that back if I bought his system.

 

[Exfarmer]

I think the 100Kw system including DNO upgrade, will actually take 12 years to pay back if you use half the power and borrow the money at 6 %.
If you are currently running the plant on your existing supply I think it extremely unlikely you will use anything more than 20 % of the power, without a huge battery system in place, and it will take your pay back, possibly beyond your FITS period.
I can run the figures very easily and quickly if you wish to send me the following. Estimated install costs I actually allowed £95K Battery cost estimated? power usage based on hourly figures for the fridge plant? expected interest rate?
Will you have to pay rates? This would be £8 x .48 x KW installed
do not forget metering cost for export £650 / annum
feel free to PM me