[No longer] Going for a Givenergy 8.2 kWh AC Coupled battery

Reed_Richards

JKenH said:

How quickly does the battery respond ...

I think it is the inverter that controls the timing.  If the sun comes out from behind a cloud it does not immediately direct full (spare) power to the battery so there might be a short period of an export which a solar diverter could pick up so you would end up heating your water instead of charging the battery.  If the sun goes behind a cloud then battery might switch to providing power to the diverter and you drain the battery.

There is a similar problem if you boil a kettle (or similar).  If this is battery assisted when the kettle turns off the battery will briefly export power to ramp down its output.  If this export is seen as spare solar power by the diverter you could again drain the battery unintentionally.         

QrizB

JKenH said:

Magnitio said:

I decided to get a battery to reduce my stress levels when my wife does the cooking and washing when the sun isn't shining. I also have the fun of working out how to maximise income from the agile Octopus.

How quickly does the battery respond on days when clouds are scudding across the sky and the sun is popping in and out?

As R_R says, the battery is a simple electrochemical device and responds pretty much instantaneously. It's the inverter that takes time to switch.

My Sofar switches within one update cycle of my smart meter IHD; if I eg. put the kettle on the load will shoot up then drop back down with the next update. I haven't timed it but I'd guess not more than 3-4 seconds?

Reed_Richards

Whereas my battery appears to respond much more slowly but that is based on data supplied by the inverter.  Those reading are updated more slowly and I don't know if the reading is instantaneous or some sort of average. 

Magnitio

QrizB said:

JKenH said:

Magnitio said:

I decided to get a battery to reduce my stress levels when my wife does the cooking and washing when the sun isn't shining. I also have the fun of working out how to maximise income from the agile Octopus.

How quickly does the battery respond on days when clouds are scudding across the sky and the sun is popping in and out?

As R_R says, the battery is a simple electrochemical device and responds pretty much instantaneously. It's the inverter that takes time to switch.

My Sofar switches within one update cycle of my smart meter IHD; if I eg. put the kettle on the load will shoot up then drop back down with the next update. I haven't timed it but I'd guess not more than 3-4 seconds?

I have similar experience with Huawei inverter; it reacts quickly to change in solar output based on IHD readings.

zeupater

Reed_Richards said:

JKenH said:

How quickly does the battery respond ...

I think it is the inverter that controls the timing.  If the sun comes out from behind a cloud it does not immediately direct full (spare) power to the battery so there might be a short period of an export which a solar diverter could pick up so you would end up heating your water instead of charging the battery.  If the sun goes behind a cloud then battery might switch to providing power to the diverter and you drain the battery.

There is a similar problem if you boil a kettle (or similar).  If this is battery assisted when the kettle turns off the battery will briefly export power to ramp down its output.  If this export is seen as spare solar power by the diverter you could again drain the battery unintentionally.         

Hi All

This is a really important point that many fail to consider when looking at installing battery systems. I've seen mention of energy storage response times ranging from virtually immediate where UPS/EPS backup is required right through to somewhere around ~30 seconds of power ramping (both up and down), which obviously results in huge differentials in battery system viability or payback calculations.

The main reason (/excuse) for extending the power ramping period seems to revolve around protecting the batteries and therefore increasing their useful lifespan - however, the argument for a kettle switching requirement of 3kW on ~10kWh of domestic LFP batteries (0.3x load to capacity) requiring considerable ramping seems to be totally out of step with an EV with (say) ~60kWh of LFP battery capacity capable of delivering (say) ~150kW under acceleration (2.5x load to capacity), so around an 8x higher ratio yet still capable of (say) ~1million miles to ~70% remaining degraded capacity, so well over 4000 cycles in a considerably more demanding environment .... seems like the reason (/excuse) tends to fail under some very fundamental & basic scrutiny!

Perhaps this should be the subject for a dedicated thread (?). where battery system response times can be shared & discussed as I've seen very little comparison of this 'feature' anywhere ....

HTH - Z 

#Edit - Done, New thread link - https://forums.moneysavingexpert.com/discussion/6358224/domestic-battery-storage-systems-energy-storage-response-times-ramping-delays   

Indio

8.2kWh GE battery, HY3.6 GE inverter, 3.34 kWh solar Panels. I'm paying less for energy this year than last year when I was still on a pre invasion tariff. I now don't use any ( well 2-3kWh pcm of daytime (high priced) electricity when I previously had to struggle to keep my usage of daytime down to 100 kWh pcm. I'm not even bothering to claim export to OVO because this would mean losing my economy 10 meter, they only do an Econ 7 smart meter. This is even with an ESE facing roof. OVO also give 5% on any credit which until recently was better than most savings accounts and probably works out at more than current export tariff would be. At current prices, I reckon the whole system will pay for itself in well under the 7 years estimated, well worth it.

1961Nick

2nd_time_buyer said:

Have you factored in the roundtrip losses?

For solar energy stored and going back to the grid, there would be losses for-

-DC (solar) to AC inverter

-AC to DC charge inverter
-Battery charging

-Battery discharging 

-DC to AC (grid) 

I am genuinely not sure what the total of that lot is but I wouldn't be surprised if it was upwards of 20%

My round trip loss (metered) is 20.83%. I use 9p/kWh rather than the 7.5p/kWh Intelligent Octopus off peak tariff for my savings spreadsheet.