Is solar battery storage worth it?

Freepost

Qyburn said:

Freepost said:

Can somebody please check my maths, 

The missing bit is export credits. On metered export you could be receiving 1200 x 15p = £180.00 per year. But I don't know what you currently receive for deemed export, nor whether you'd still retain that payment after adding a battery.

There is no deemed export. With my system being installed in 2011 the current FiT provides me with a generation tariff of 71.85p/kW plus export tariff of 5.07p/kW x 50%. Combined = 74.38p/kW which over a year = £2380.16.

Adding a battery would make no difference to the income, the meter simply calculates how much the system has generated with an assumption that 50% is exported.

Reed_Richards

Freepost said:

Qyburn said:

Freepost said:

Can somebody please check my maths, 

The missing bit is export credits. On metered export you could be receiving 1200 x 15p = £180.00 per year. But I don't know what you currently receive for deemed export, nor whether you'd still retain that payment after adding a battery.

There is no deemed export. With my system being installed in 2011 the current FiT provides me with a generation tariff of 71.85p/kW plus export tariff of 5.07p/kW x 50%. Combined = 74.38p/kW which over a year = £2380.16.

Adding a battery would make no difference to the income, the meter simply calculates how much the system has generated with an assumption that 50% is exported.

The assumption that 50% is exported is what is called "deemed export" because it is deemed to be 50% of what you generate rather than anything that is actually measured

Qyburn

Freepost said:

There is no deemed export. With my system being installed in 2011 the current FiT provides me with a generation tariff of 71.85p/kW plus export tariff of 5.07p/kW x 50%. Combined = 74.38p/kW which over a year = £2380.16.

On 3,200kWh generation your deemed export is therefore 1600 x 5.07p = £ 81.12.  So switching to metered export would gain you nearly £100/year.

Freepost

Qyburn said:

Freepost said:

There is no deemed export. With my system being installed in 2011 the current FiT provides me with a generation tariff of 71.85p/kW plus export tariff of 5.07p/kW x 50%. Combined = 74.38p/kW which over a year = £2380.16.

On 3,200kWh generation your deemed export is therefore 1600 x 5.07p = £ 81.12.  So switching to metered export would gain you nearly £100/year.

So, if I am understanding this correctly, I can switch to a metered export and retain the FiT?

So, how do I sign up?

Back to the question though "is solar battery storage worth it?, I assuming that it wouldn't be cost effective for my system.

Thanks for your help.

F

Qyburn

Freepost said:

Qyburn said:

On 3,200kWh generation your deemed export is therefore 1600 x 5.07p = £ 81.12.  So switching to metered export would gain you nearly £100/year.

So, if I am understanding this correctly, I can switch to a metered export and retain the FiT?

That's correct. There are a few hoops to jump through to go metered. You need a smart meter for a start. You'll need to look out your MCS certificate and G.83 notification, you would have needed those for the FIT application. Your supplier will need these to get your smart meter enabled for them to collect export data.

Generally you get the best export rates if you're also a supply customer of the supplier. But you can change supplier while leaving the FIT generation with whoever it's with at the moment.

mickyduck55

greenmeany said:

Having just read the article about batteries and solar power I would like to see a reference relating to those of us on the old Feed in Tariff having had Solar Panels for around 12 years now. We got in under the line when the government decided the scheme was too generous and was dealt with by the European Courts! Never been so lucky in my life.
My panels have paid themselves off and raised a further £5.5k in profit....yes,  and I get a "deemed" payment of 0.0482p per kWh from assumed use  and 0.6830p per kWh for generated energy back to the grid.  Anyone in my position would be bonkers to even consider buying a battery and should be warned...there be sharks....

I am in a similar position to you with the same FIT however I do have batteries.  I do not see where your logic lies here battery or no battery you will still get the same deemed export and the same export generation payments.  With the battery you will use a lot more of your generated power.  I have actually moved to metered export rather than deemed as Octopus will pay me 15p rather than the 5p you are receiving. 

retireby50

NedS said:

Qyburn said:

PDoffwiththeBBC said:

Hi,

    A much cheaper way of "storing" your excess solar output is to use an immersion diverter. 

Surely that only makes economic sense if your normal water heating costs you more than 15p/kWh. Otherwise you're better "storing" you excess in the grid.

Exactly - gas is priced at around 6p per kWh and excess solar is worth 15p per kWh (assuming SEG of 15p), so you'd be much better off exporting excess solar at 15p and then paying 6p to heat your water as required with gas.

One of the problems with this discussion and working out what is best is there is a tendency (me included) to assume "our" situation applies to all. For example the above: I have an immersion diverter and it makes absolute financial sense (for me) as I am on the original solar tariff where get a low rate for an ASSUMED amount sent back to the grid (50% of my output). So I get paid the same amount irrespective of how much of the generated energy I use. So previously a direct gas saving and now, with an ASHP, direct electricity saving. Obviously different if you get paid for the actual energy sent back to the grid, but even then different if you have ASHP vs gas boiler. As an interesting (?) aside it's noteworthy how much less PV is being diverted with my nice new tank!

powerful_Rogue

Just read the guide and it's very poorly written. Why on earth are you calling it a 'solar battery'?

Alternatively, you could have a domestic wind turbine installed in your garden, and use a battery to store the energy its generates.

Yeah, at over £20k for a 5 kWh wind turbine.

retireby50

Freepost said:

Is solar battery storage worth it?

I have a 3.8kw solar PV system, installed Nov'2011, and I had pondered the installation of batteries for the past years but I seem to have a mental block on justifying the addition of batteries to the system. 

Prior to the installation of Solar PV my annual electricity consumption was ~ 4800kWh. Since the installation my average consumption has reduced to 2800kWh. For me this indicates that the system has saved me 2000kWh/year. 

The solar PV system is generating ~3200kWh/year and from the above, I am using ~2000kWh with the other 1200kWh being lost to the grid. Now if I install batteries then I can store and use this 1200kWh, perhaps nearer a 1000kWh with incurred loses, and that's money saved but what will I save? The cost of a kWh from Octopus is approx. 26p which times a 1000kWh = £260.00/a, would this saving justify the cost of installing battery storage? I don't think it does, remembering that my system was installed in 2011 and that I am only guaranteed the FiT for 25years which means that I only have 12 years left and 12 x £260.00 = £3120.00. 

Can somebody please check my maths, I may have done something stupid, I also fully understand that my system will not stop working in 12years time but the FiT does.

Thanks

F.

Not sure what impact your FIT has on your potential savings from batteries. Assuming your figures are correct it's £260 per year for any FIT or no FIT, isn't it? (If you have a real export tariff then that does impact).

Having said that my rough calculations always lead me to the same conclusion. Take your 1200kWh assumed export which can potentially be stored - you've assumed 1000 stored and used, and this is my area of concern. I'm probably being too simplistic, but to get near to maximise savings I need to fully charge my battery with surplus PV and then use it before I have surplus PV again. The problem is the time of year I could fully charge my battery (with PV) is the same time of year I would struggle to empty it. Having an EV would significantly help address this issue.

One saving you haven't taken into account, and that is perhaps because you appear to have  a single rate for electricity, is the potential to charge your battery on a cheap rate to be used, say, during the day when rates are higher.

Even taking that into account I still couldn't make batteries pay within 10-15 years. 

Others are much more positive and almost certainly more knowledgeable on the matter.

EricMears

Freepost said:

The cost of a kWh from Octopus is approx. 26p which times a 1000kWh = £260.00/a, would this saving justify the cost of installing battery storage? I don't think it does, remembering that my system was installed in 2011 and that I am only guaranteed the FiT for 25years which means that I only have 12 years left and 12 x £260.00 = £3120.00. 

Can somebody please check my maths, I may have done something stupid, I also fully understand that my system will not stop working in 12years time but the FiT does.

Thanks

F.

Rather surprised that you're paying Octopus 26 ppu at the moment.   I'm on a split tariff (Intelligent Go) and my daytime rate is only 22.784 and I'd really expect a single rate tariff to be less than my daytime rate.

The real saving that I make from my batteries is that I import very little at the daytime rate - batteries are charged from solar panels (effectively free as I too am on deemed export) or at my off-peak rate of 7ppu.

You can't of course join OIG unless you have an EV but there are other split tariffs available from Octopus that would allow overnight imports at a lot less than 26ppu.