Solar storage

[jason121]

Can anyone recommend a decent storage system for a domestic installation.
Going to try and install 10kw and customer wants to store some and use at night

Thanks

 

[infinity]

I've used Nedap, good system, expansive though!
I like the idea of emergency backup as well on it.
Easy to install and monitoring is good, you can also change all settings or even reset it remotely of you like

 

[Worcester]

And the cost per kWh of the storage over its lifetime?

There is some new battery technology in the pipeline that within 5 years is really going to open this market up

 

[Gavin A]

about 5p per kWh for the forklift batteries we're sourcing.

a lot depends on the usage and charging rates to determine the number of cycles the batteries can cope with before dying, and the batteries being sold by UK Nedap suppliers will all die inside 6 years at the recommended daily discharge levels, but if it's done right with the right batteries I'm relatively confident it can be made to just about make economic sense - at least for someone who places a value on the back up capacity in case of grid failure.

 

[SolarPro]

I've used Nedap, good system, expansive though!
I like the idea of emergency backup as well on it.
Easy to install and monitoring is good, you can also change all settings or even reset it remotely of you like

I do agree with Infinity.
Happen to know Nedap (Dutch company). But the number of suppliers is rapidly increasing, especially in the German marketplace. Most of them are Li-Ion.
But cost-price will remain quite heavy. Price slashing is expected to occur (half the current price) in 4 to 5 years.
Alternative strategy (widely discussed in Germany and to some extent in the UK as well) is increasing self-usage of solar energy. This also means reducing the size of the required storage.

 

[jason121]

Whats the payback figures like

 

[SolarPro]

Hope this helps Jason. It's not easy to translate the figures from the German marketplace to the UK, since investment in self storage is heavily subsidised in Germany.

Anyone who buys a new storage system with a new PV system will receive up to €600 per kilowatt-peak installed.
But despite the funding, lead batteries will still cost operators an additional 10 to 15 Eurocents per kilowatt-hour of stored PV power. Users of lithium-ion batteries should expect to spend even more: between 20 and 25 Eurocents per kilowatt-hour.

 

[SolarPro]

Hello Jason,

I have gone through the figures which I supplied above because they don't seem very plausible (ouch, I didn't check them).

I made calculations myself. I have taken two current systems, both Li-Ion, because they will last longer, although they are on average 30% more expensive than lead batteries.
One is a system from SMA, the other from IBC Solar.

The SMA storage system has a usable storage capacity of 4,4 kWh.
It would last about 6000 cycles, which means it can last 20 years.
The system storage capacity will degrade about 0,5% a year (in 20 years from 4,4 kWh to 3,96 kWh).
This means the battery is able to store 83.380 kWh in 20 years (assuming optimal use !!).
This system costs € 11.500,- (without installation) and without German subsidy.
The cost per kWh would be € 0,138

The IBC Solar system has a usable storage capacity of 4,5 kWh.
It would last about 5000 cycles, which means is lasts 15 years.
We work with a similar degradation of 0,5% a year.

It is able to store 64.800 kWh in 15 years (assuming optimal use !!)
It costs € 9000,- (without installation).
The cost per kWh is quite similar: € 0,1388

I think this is a more suitable answer, although it is still pretty expensive.

In the German situation (feed-in tarif: € 0,16 and an electricity price of
€ 0,28 p/kWh) there is no solid business case. It can only be done with subsidy. A storage like the IBC Solar with a nominal capacity of 5 kWh, would receive a subsidy of € 3500,-.
Of course we didn't take into account a potential increase in electricity prices (during the lifetime of the storage).

Comparable figures can be calculated for other types of Li-Ion and lead batteries.

 

[SolarCity]

With cheaper electricity in UK, the case for storage is even harder to make.

 

[Worcester]

I had a look at two systems at ecobuild this year (one not on display though may be next year ) both came out at UK grid parity costs, i.e the cost of the system over it's lifetime amounted to the cost of the electricity.

And if you take the example above, they are starting to stack up - it costs €0.138 / kWh yet we buy in a €0.18 /kWh so if grid stability is also a concern for you, then they now make economic sense. - Charging from the grid doesn't however seeing as in the UK we are NOT on net metering and are paid on generate and export whether we do or not, storing the excess over self consumption add up