On-grid domestic battery storage

rugbyleaguesmate wrote: »

Hi Mart thank you my efforts are below, struggling with format.....

Hiya RLM, for a persistent waffler like me, the formatting on here is a right pain.

If I'm reading your info right, the cross over point for export v's import seems to be around October/November with rising import v's falling export.

I can't see export figures for the summer, but I assume they are very high, and it looks like import is a relatively consistent 9kWhs/day?

Winter looks like a low export of 4/day in Dec but rising fast in Jan (and Nov) so perhaps better to use their low of 7/10, not the 4.

So, my gut feeling, and ignoring all battery losses at this stage, is that on most days, on average, you have 7kWhs+ of export, and an import of 9kWhs+.

So there's the logical smallest USEABLE battery capacity, but since you rapidly meet and exceed the 9kWh mark then the sensible useable battery size is actually 9kWh+.

Simply for comparison, not a suggestion, the PWII has a capacity of about 15kWh, and useable of about 13.5kWh. I assume that avoiding the top and bottom of that range would reduce any loss of capacity over time, and since we are dealing with averages, not actual individual days, then a larger batt will cope with better generation days, and also provide for bad gen days, or a number of days.

So my gut feeling is that you'd want something of that size. What do you think?


Savings wise, and I'm going to oversimplify this, but if we say average out the Nov/Dec/Jan months to about 7kWh's, let say 6, just to be safe, and the rest of the year to 9kWh's, then you might expect (hope) to reduce import by:-
(92 x 6kWhs) + (273 x 9kWhs) = 3,009kWhs

3,000 x 16p = £480pa.

But, as ET points out, is that a NSC tariff, or have you just calculated it in?

If for example the price is say 13p + SC, then savings are £390pa.

The UK PWII site suggests a starting price of £6,700. I assume the 'permitting costs' referred to are just a standard line as it appears in all country quotes, I don't think there are any in the UK.

So it would take you around 14-17yrs to repay, assuming we ignore interest.

I hope this all makes sense, but there is a lot of guesswork and assumptions thrown in, which is another good reason to carrying on waiting.

I also think we shouldn't waste an opportunity that already exists, and this is that Germany and Australia are rolling out lots of storage systems, and I suspect wealthier mainland US households will be doing this too. So we can sit back this decade and see how the systems hold up, what their performance is, how rules change (Australia may require Li-Ion systems to be installed outside) etc etc etc.

Any help?

This article on storage in the Western Power and Distribution (DNO) region, might be better placed on the green energy news thread, but I think it's ok here due to this bit on domestic storage:-

Wave 1 (up to 2020) - Led by response services
Domestic and community scale early adopters.

Wave 2 (early 2020’s) - Co-location business models become viable
The domestic and community storage market expands.

Wave 3 (mid/late 2020’s) – Market expansion and new business models
Domestic electricity storage becomes common


WPD investigates the future of storage following ‘unprecedented’ applications

Western Power Distribution (WPD) has launched a consultation seeking views on the potential growth of energy storage on its distribution network after receiving an ‘unprecedented’ 8GW of applications in the last 18 months.

According to the consultation, WPD has already accepted 1.13GW of battery storage capacity as of 3 May 2017, with a further 1.1GW offered to existing applications. These projects mark a significant increase on the 2.85MW from an existing project and one that WPD is now preparing to accommodate.

Significant increase ....... it's 1,000 times more! :shocked:

Sonnen, Senec and LG Chem dominate growing PV storage market in Europe

On Monday, the German Solar Industry Association (BSW-Solar) also published its current “storage price monitor”. According to this, the costs for storage systems up to a nominal capacity of 10 KWh have decreased by about 40 percent over the past four years. For larger battery systems up 30 KWh the prices have even halved within the same period.

“Due once again to the drop in prices, solar energy storage is becoming increasingly attractive. Accordingly, the demand for solar power storage will continue to rise,” explains Carsten Körnig, CEO of BSW-Solar.

For example in 2016 about 20,000 new installations were added, totaling 60,000 PV storage systems in operation in Germany. The PV storage market in the country is expected to continue to grow and to reach 30,000 new installations for the year 2017, as EuPD Research says.

Also big news on large scale storage in the US, which may have a trickle down influence on future storage costs.

Some time back a PV + storage contract was issued at 14c/kWh, then Tesla stepped in with an 11c/kWh contract in Hawaii. Now Tucson has beaten that by an ickle bit, with a 4.5c/kWh contract (3c/kWh for the PV leccy).

Updated: Tucson Electric signs solar + storage PPA for 'less than 4.5¢/kWh'

If this comes about, and at that price, then that's an absolute killer. No two ways about it, that will re-write the rule book in the US.