Battery only storage - Worth it?

[Creakyride]

After a big disappointment with a solar installation and still chasing my money back off the credit card company, I am wondering if having only a home battery storage make more sense.

A new company taking some selective job from the company that has gone under, is offering to do the solar installation for the same price I had agreed with the previous company. After going through the specs, I am not convinced that the intended supply of a Sun Synk inverter would perform that well for my 2 string setup. The company want to instal 4 of the 10 panels on a North East 40° slope roof. The problem I see with this is that the hybrid 3.6KW inverter has a start up voltage of 150V. I am no electrician but I don't think that it would work well.

So I am thinking to go for the battery only route... Is this a wise decision?

Currently the house needs around 10-13KW of electricity and I have just came in possession of a new EV with a possible need of around 40KW weekly.

Keen to hear any suggestions.

What would you do?

 

[binky]

What would I do, be wary of the new company. I would check out the directors for any links to the old company.

 

[johnb2713]

So I am thinking to go for the battery only route... Is this a wise decision?

Keen to hear any suggestions.

What would you do?

I have done both over the last year - solar + battery and an additional battery and inverter. The solar and battery is brilliant when the weather is good and about as much use as a chocolate teapot during winter. My standalone battery and inverter is easy to calculate the cost savings. 21kWh usable, so that gets charged from grid if you dont have solar, peak electricity is £0.38, off peak is £0.075 therefore a saving of £0.305. 21kWh @ £0.305 = £6.40 per day. Fogstar batteries are £1350 for 5kWh so 4 of those would give you 20kWh, a 5kW inverter would be circa £1000, total cost of a system like this £6400, payback 2.75 years.
Obviously the size of battery can be reduced with appropriate savings in cost, a 10kWh system would be £3700, payback would be 3.3 years based on the same figures.
If I had my time over again, I wouldn't bother with the solar PV.

 

[binky]

I have done both over the last year - solar + battery and an additional battery and inverter. The solar and battery is brilliant when the weather is good and about as much use as a chocolate teapot during winter. My standalone battery and inverter is easy to calculate the cost savings. 21kWh usable, so that gets charged from grid if you dont have solar, peak electricity is £0.38, off peak is £0.075 therefore a saving of £0.305. 21kWh @ £0.305 = £6.40 per day. Fogstar batteries are £1350 for 5kWh so 4 of those would give you 20kWh, a 5kW inverter would be circa £1000, total cost of a system like this £6400, payback 2.75 years.
Obviously the size of battery can be reduced with appropriate savings in cost, a 10kWh system would be £3700, payback would be 3.3 years based on the same figures.
If I had my time over again, I wouldn't bother with the solar PV.

if only you could get a decent FiT!

I would tend to agree, batteries are greener than people think, becuase to max the benefit you need to charge on off peak over night, soaking up energy from sources like wind. Effectively, the government wants us to do this, as it saves them having to build massive battery systems.

 

[Creakyride]

I have done both over the last year - solar + battery and an additional battery and inverter. The solar and battery is brilliant when the weather is good and about as much use as a chocolate teapot during winter. My standalone battery and inverter is easy to calculate the cost savings. 21kWh usable, so that gets charged from grid if you dont have solar, peak electricity is £0.38, off peak is £0.075 therefore a saving of £0.305. 21kWh @ £0.305 = £6.40 per day. Fogstar batteries are £1350 for 5kWh so 4 of those would give you 20kWh, a 5kW inverter would be circa £1000, total cost of a system like this £6400, payback 2.75 years.
Obviously the size of battery can be reduced with appropriate savings in cost, a 10kWh system would be £3700, payback would be 3.3 years based on the same figures.
If I had my time over again, I wouldn't bother with the solar PV.

This is the reason why I am debating if to go for the battery only option.

I can see the positive in my negative experience, no pan intended.

So, what kind of inverter is normally used for battery only?

What is the maximum charging/discharge of a 5 kw inverter?

How much should I allow for installation cost?

Would I need to insulate my old garage against extreme temperatures changes? It's has no heating and the a corrugated metal roof, so it's cold in the winter and in the summer.

Would I need to use installers with some kind of certification?

 

[bladerunnerpv]

If I had my time over again, I wouldn't bother with the solar PV.

Know you're very keen on your batteries John, I never though I'd hear you say this though!

 

[bladerunnerpv]

Creakyride, IIRC there was a thread a few months back looking at pros, cons of solar PV + battery or just battery. I'll see if I can dig it out

Edit: This one...
https://electricianforum.co.uk/threads/solar-panels-vs-battery-only.55863/
Also IIRC no VAT if you have panels a part of the install, but if it's lots cheaper without panels then that's a moot point.

 

[binky]

Creakyride, IIRC there was a thread a few months back looking at pros, cons of solar PV + battery or just battery. I'll see if I can dig it out

Edit: This one...
https://electricianforum.co.uk/threads/solar-panels-vs-battery-only.55863/
Also IIRC no VAT if you have panels a part of the install, but if it's lots cheaper without panels then that's a moot point.

Installation costs will be far lower than fitting panels on a roof.

 

[Creakyride]

I need a quote from a reliable source for an install in Oxford.

 

[matt.bram]

I have done both over the last year - solar + battery and an additional battery and inverter. The solar and battery is brilliant when the weather is good and about as much use as a chocolate teapot during winter. My standalone battery and inverter is easy to calculate the cost savings. 21kWh usable, so that gets charged from grid if you dont have solar, peak electricity is £0.38, off peak is £0.075 therefore a saving of £0.305. 21kWh @ £0.305 = £6.40 per day. Fogstar batteries are £1350 for 5kWh so 4 of those would give you 20kWh, a 5kW inverter would be circa £1000, total cost of a system like this £6400, payback 2.75 years.
Obviously the size of battery can be reduced with appropriate savings in cost, a 10kWh system would be £3700, payback would be 3.3 years based on the same figures.
If I had my time over again, I wouldn't bother with the solar PV.

Very insightful, thank you.

Do you factor in the life/cost of battery when working out the ROI?

 

[binky]

I need a quote from a reliable source for an install in Oxford.

Any electrician can install a battery.

 

[Creakyride]

But what about installing and configuring the inverter and dealing with the g99 and DNO?
I know an electrician but unfortunately he doesn't deal with solar PV or battery. I will look to find someone else I guess.

 

[Oldman22]

But what about installing and configuring the inverter and dealing with the g99 and DNO?
I know an electrician but unfortunately he doesn't deal with solar PV or battery. I will look to find someone else I guess.

Also don't forget the MCS certification should you wish to export at all this it seems is a requirement.

 

[johnb2713]

Know you're very keen on your batteries John, I never though I'd hear you say this though!

Dont get me wrong, solar is impressive and it's an amazing feeling to be driving around with energy from the sun. In pure financial terms, the batteries are much better bang for your buck. Another thing thats really good is the brighter the sun, the more AC I can run from the solar, it's been pretty cool in my house for the last few weeks

 

[johnb2713]

Very insightful, thank you.

Do you factor in the life/cost of battery when working out the ROI?

The EVE cells I've used in my batteries (and the Fogstar ones mentioned) have a predicted life of 6000 cycles, a cycle is fully charged and discharged. Assuming one full cycle per day, that's 16.4 years. A couple of points, the batteries don't fully cycle every day so that 16 plus years is longer and when they're deemed end of life is when their capacity drops to 80%. Even at end of life they're still providing worthwhile storage eg 20kWh would be down to 16 kWh.

 

[binky]

Also don't forget the MCS certification should you wish to export at all this it seems is a requirement.

If you have battery only, why would you want to export? I know some people do this, but, if you export the cheap leccy you charged the battery with, it's then not available when you want it, so you end up buying leccy at standard rates. Plus you would have to pay MCS registered installer £k extra for the work.

 

[johnb2713]

If you have battery only, why would you want to export? I know some people do this, but, if you export the cheap leccy you charged the battery with, it's then not available when you want it, so you end up buying leccy at standard rates. Plus you would have to pay MCS registered installer £k extra for the work.

A few people are driving their systems following the likes of Octopus Agile (there are a few inverters that link into this automatically). Buy when it's cheap and sell back when it's at a premium. It's possible to make very good money at times.

 

[Andy1733]

I'm agreeing with John. Battery only is prob the better option (whilst cheap rates are available) My panels are south facing and are pretty useless for 4 month of the year. Yeah they make some power during the winter but nothing noticeable.

 

[Mr Aargh]

North facing isn't suitable for solar at all. You may want force discharge capability to exploit agile prices properly.

 

[binky]

A few people are driving their systems following the likes of Octopus Agile (there are a few inverters that link into this automatically). Buy when it's cheap and sell back when it's at a premium. It's possible to make very good money at times.

I get that, but are they paying out more than the standard rate you would have to buy leccy at if your battery is flat if an evening?

Has to be said, it would be good for RoI if you have a larger battery than you need. Sonnen were talking about this years ago, although I don't think they ever really got off the ground in the UK.