Battery only storage - Worth it?

[BorisJ]

All these calculations assume the batteries are 100% efficient, i.e. you get out as much as you put in. You don’t. I don’t know about modern lithium ion batteries but previous batteries the figure was about 70%.

 

[johnb2713]

All these calculations assume the batteries are 100% efficient, i.e. you get out as much as you put in. You don’t. I don’t know about modern lithium ion batteries but previous batteries the figure was about 70%.

My Victron system runs at approx 93% efficient (energy in to energy out).

 

[johnb2713]

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.

Heres today:

 

[Creakyride]

Do the kits come with full instructions?

Does the home insurance company need to be notified?

 

[johnb2713]

Do the kits come with full instructions?

Batteries and inverters have manuals of varying degrees of detail.

Does the home insurance company need to be notified?

I told ours of the solar and battery installation, it was added to the building insurance with no increase in premium but a £15 service charge was made.

 

[binky]

Heres today:

View attachment 15695

Average UK price is 34p per Kwh according to a quick google, so it would only really be worth selling back to the grid between 16.00 and 18.30. Even then you are down a ha'penny for any energy purchased due to lack of battery stored energy. Every ha'penny counts you know .

This Sonnen video doesn't discuss money for energy sold, but is a good example of how smart energy networks are proposed to work.

 

[Creakyride]

Batteries and inverters have manuals of varying degrees of detail.


I told ours of the solar and battery installation, it was added to the building insurance with no increase in premium but a £15 service charge was made.

Thank you @johnb2713.
I want to have all my ducks in a row before I try talking to an electrician to do the job.

 

[johnb2713]

Thank you @johnb2713.
I want to have all my ducks in a row before I try talking to an electrician to do the job.

The electrical installation is simple.

Grid supply onto inverter. (this may need a separate small consumer unit)
DC Supply from batteries to inverter
comms cable from battery to inverter
CT from inverter around meter tail.

Job done.

 

[bladerunnerpv]

A curve ball to to bear in mind perhaps

It's possible to find, for ukpowernetworks at least, information on your local grid primary substation and the substation loading and headroom and remaining headroom predictions thereof.

In my area it's indicating demand is increasing and excess demand, i.e. zero headroom in capacity, will be reached by 2031.
Nearby town 10miles up the road is between 5% overload and 5% headroom now

Projection depends on what growth factors they're taking into account, e.g. new housing planned, EV usage growth, industry demand, more extreme weather variation, etc etc, and the assumptions being made of course.

Point is that the grid is gradually heading towards insufficient available capacity vs the demand, I would presume supply may also become less reliable as headroom reduces.

Battery storage systems in the home will help with load balancing, a solar component will help even more presumably and potentially give you supply when the grid can't.

 

[matt.bram]

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.

Interesting. Roughly how much does that work out per kWh?

 

[johnb2713]

Interesting. Roughly how much does that work out per kWh?

See post #3

 

[Jedw]

Not posted for a while, but this topic is of interest. I agree with John and some others. I have a Solis Hybrid 6kW and 4 * pylontech US5000. Perfect for me all year round as on Octopus Go, 8.25p off peak . I use something like 0.3kW max peak daily as the inverter arbitrates the grid potential on load step changes. But I am considering an ASHP ( A2A) and gas aga conversion to my own design electric conversion, Alexa linked, so looking at another 4 pylontech US5000 as opposed to a 5kWp solar install. At 8.25p / kWh or less if I go onto Octopus intelligent, why install solar ( even though, like lots of others, I like the idea of generating...for 8 months of the year...when I probably won't need heating !! and 10kWh battery storage capacity is enough ) The 4 extra plyontechs and 6-7 hours of off peak make perfect financial sense. charging at at night while the home, ASHP and AGA all get up to temp on the off peak grid.

 

[Jedw]

btw...the added advantage of having battery storage only...if you sell your home and move...and the buyer won't fork out for your inverter storage system....it's as easy as taking your washing machine or fridge/freezer with you...lol
solar not so easy !!

 

[binky]

btw...the added advantage of having battery storage only...if you sell your home and move...and the buyer won't fork out for your inverter storage system....it's as easy as taking your washing machine or fridge/freezer with you...lol
solar not so easy !!

Solar is a selling point these days.

We are thinking of moving in a few years time. Losing my solar system and FiT payments will be a barsteward

 

[Geoff1946]

There are hundreds, more likely thousands of new houses being thrown up, sorry built around here and the roof structures look to be getting flimsier by the week. I have to wonder of these are stressed to take solar panels, or offer adequate fixing. Anyone know if this is an issue?

 

[Creakyride]

@johnb2713

Hi John. I had a look at the Fogstar batteries and liked the look of this:
https://www.fogstar.co.uk/collectio.../fogstar-energy-48v-15kwh-rack-battery-bundle
In the specs, it mentions that these batteries will provide 6000 cycles at 50% DOD, and 4000 cycles at 80%.
I am not sure if all lithium batteries give the same performance. I have not seen this 6000 Cycles @ 50% DOD before... Not sure is something ithe manufacturers tend to hide or not.

 

[Oldman22]

By the time 4000 cycles (10+yrs) are up we will be using the next big thing in storage

 

[johnb2713]

Octopus at one point were offering pre-built roof systems which included solar et

@johnb2713

Hi John. I had a look at the Fogstar batteries and liked the look of this:
https://www.fogstar.co.uk/collectio.../fogstar-energy-48v-15kwh-rack-battery-bundle
In the specs, it mentions that these batteries will provide 6000 cycles at 50% DOD, and 4000 cycles at 80%.
I am not sure if all lithium batteries give the same performance. I have not seen this 6000 Cycles @ 50% DOD before... Not sure is something ithe manufacturers tend to hide or not.

EVE cells are the best in the field second to none. It looks a tidy unit for sure.

 

[Creakyride]

On the Fogstar literature it mentions something about the fact that those battery banks do not require an inverter to work. That's puzzling... I wonder how would the AC/DC/AC conversion happen?
Surely it needs an inverter!

I assume a standard inverter would be required, without the need for hybrid? This should cost less too.

 

[Jedw]

he 4 extra plyontechs and 6-7 hours of off peak make perfect financial sense. charging at

what I was intending to point out is payback of solar over battery is much longer if you are buying cheap off peak energy versus peak expensive energy....thats why I wouldn't for for solar in my situation.

Losing my solar system and FiT payments

ahhhh....one of the lucky few .....a lucrative FiT

I assume a standard inverter would be required, without the need for hybrid? This should cost less too.

Quite right Creaky...sorry...its only a battery system...very nice though with self heating and builyt in DC breaker.....you still need to go from 52VDC to 220 AC using a suitable inverter