On-grid domestic battery storage

JD800 · 9 August 2017 at 3:11PM

Mart,
I'm not able to post the full spec sheet so here are edited highlights
Pylon tech US2000B - the latest HESS battery system provided by Pylontech
Advantages
Vertical industry integration ensures more than 6000 cycles with 80% DoD
Deliver up to 5KW with single module (2.4KWh)
Modular design gives the end customers the power of choice of capacity
Compatible with most of the available Hybrid inverters
Simple buckle fixing minimize the installation time and cost
Compact and fashionable design fits in your sweet home environment
Safety Cert.TÜV􀀁CE􀀁UN38.3􀀁TLC
SPECIFICATION BASICPARAMETERS US2000B
Nominal Voltage 48 V
Nominal Capacity 50 Ah
Dimension (mm) 440*410*89
Weight (Kg) 24 Kg
Discharge Voltage (V) 45 ~ 54
Charge Voltage (V) 52.5 ~ 54
Peak Discharge Current (A) 5kW@1Min
Peak Charge Current (A) 5kW@1Min
Communication RS232, RS485, CAN
Charging Temperature 0 ~50C
Discharging Temperature -10~ 50C
Shelf Temperature -40~80C
Certification TÜV / CE / UN38.3 / TLC
Design life 10+ Years (25deg C / 77deg F)
Cycle Life >6000 ( 80% DoD) - although salesman assures me this is now 90 % DoD

For interest only now as I think my further calcs will show I may spend darker months not charging the battery enough to make it worthwhile and summer months only using the battery to replace off peak (7p) units. I've some more work to do with Zeup's links to see whether I can tweak the timings for my GSHP to better utilise whatever PV I can generate.
Going to re-measure roof to see if I can squeeze a few more panels on whilst scaffolding is in place.
Thanks again for advice / interest.
Jim

JD800 · 9 August 2017 at 3:23PM

The struggle to elicit detailed information has made me a bit circumspect about the whole battery installation. My initial quote clearly specifies a Solax battery (but this now seems to have changed to the Pylontech) and the quote states a 10 year warranty but spec sheet indicates a 10 year life but a 5 year warranty (perhaps the installers have their own warranty).
I guess some installers have a stock of "old" batteries sat around they're keen to shift which might drive special offers that don't stand up to detailed scrutiny.
Or perhaps I'm getting cynical in my old age.

Martyn1981 · 9 August 2017 at 5:10PM

Thanks JD, it was the issue of the warranty length that concerned me, as you were clearly working on 10yrs+, which seems fair, but 5yr warranty isn't enough.

There are loads of batts out there with warranties varying from 3, 5 and 10yrs and life expectancies of 2,000, 3,000, 5,000, 6,000, 8,000 cycles or 10-20yrs.

It's all a bit too confusing at the moment, another reason why I want to wait and watch to see how it resolves and what problems occur.

I have to say your first post was extremely comprehensive, all you missed was the post PV knowledge needed for a rough guess at generation, particularly monthly gen, post PV import and potential export, and that comes from having PV for 12+ months, so no way to fake that.

I suspect you'll be getting a batt in 5yrs time, hopefully me too.

JD800 · 9 August 2017 at 9:48PM

Agree that 12 months experience of PV generation with my system and varying utilisation of generated electricity will make my battery decision making more accurate / realistic.
Interesting from your PV FAQs link that the 4th saving (my more efficient use of all electricity) might also have an impact as I think a bit more about timing appliances to match max generation or off peak supply. Just need to train girlfriend to do the same - hair straightening only at Economy 10 off peak times perhaps.
I'll check in every few weeks to update on PV generation and check on battery views / sums.

reeac · 10 August 2017 at 10:32AM

Would the addition of battery storage have any influence on the assumption that 50 percent of generated power is exported? If so then there would be a slight financial impact.

Martyn1981 · 10 August 2017 at 11:57AM

reeac wrote: »

Would the addition of battery storage have any influence on the assumption that 50 percent of generated power is exported? If so then there would be a slight financial impact.

Yep, and in the long run, assuming export is metered and that figure is used, then the savings should be calculated as import rate - export rate.

For myself my export income wouldn't drop as I'd probably use an extra 800-900kWh's, and I'm typically underpaid by that amount. However, in reality, if metered, I would lose the additional income as I'd no longer be exporting more than 50%, but about 50%.

zeupater · 10 August 2017 at 12:00PM

reeac wrote: »

Would the addition of battery storage have any influence on the assumption that 50 percent of generated power is exported? If so then there would be a slight financial impact.

Hi

I doubt it in the short-run ... plenty of installations divert to DHW and it doesn't apply there. Personally, I wouldn't get too worried about the deemed percentage for the same reason as the industry doesn't ... firstly, in terms of total generation purchases it's a rounding exercise well below the decimal point ... secondly, the cost is generally in line/cheaper per kWh than almost all other daylight sources ... thirdly, in deeming at 50% the majority of those with PV are likely to be receiving less than they would if offered a metered export solution ... so there's little benefit for the industry to make a fuss as illustrated by the seeming lack of motivation to ensure that smart-meters are configured to meter exports - there's far too much money to be made by the industry through meter installation followed by time of use billing for them to divert attention to such as relatively minor issue ... maybe in the long term there'll be changes - but .....

HTH
Z

reeac · 10 August 2017 at 3:12PM

Thanks. By my reckoning if I lost all the export payments it would only be around £40 pa off the present £1100 pa so no big deal. I became interested in storage because we live in a rural area and about once a year we lose our power due to fallen trees on power lines. A 5 kWh store would keep our freezers, fridges and lights going for a day or two without the noise of a standby generator.

pinnks · 10 August 2017 at 5:07PM

I think that must depend on your FiT rates. My deemed export on 4,400kWh generated was about £110, whereas my total FiT receipts over the 12 months to June 2017 were about £800.

Martyn1981 · 10 August 2017 at 5:40PM

One more piece of the storage story slots into place as we slowly move towards a more mature industry:

IET publishes long-awaited code of practice for energy storage

On-grid domestic battery storage

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