Gen 1 3.6kw Inverter

Ultimately I'm trying to work out if it cost effective to have a second battery (currently have gen 1 8.2kw battery). Part of my rough work out is knowing the rate of charge I'm putting into the battery during the Octopus 12.30 - 04.30 slot. I've read a few articles and viewed some videos and my feeling is that, based on the winter months, I should looking at something like 2.5kwh, so 4 x 2.5 = 10kw and in the good months perhaps 4 x 3 = 12kw from the inverter. Both these figures exceed the capacity of battery so an additional battery would give me extra 'battery supplying the home' time before the battery runs out. If in the future I moved to something like Octopus Intelligent with a 6 hour window I could have 6 x 2.5 = 15 and 6 x 3 = 18. (In the summer I would have potentially lots of solar this has to be taken into account). I appreciate there are probably lots of other variables but I'm guessing I have to work on 'approximations'. Am I right in thinking, in the winter, irrespective of the overall battery size (8.2 + 5.2, 8.2 + 8.2, 8.2 + 9.5) the limiting factor is the charge rate of my inverter and time to recharge? I.e. time period x 2.5

For your inverter (and mine) the charge rate is nearer to 2.4kWh for AC conversion and is as you think the most limiting factor. The inverter will charge slightly quicker from solar @2.6kWh.

I went to Eco7 as i have Gen1 5.0 and 9.5 battery (gen 2 promised but not available at time). It charges at 2.6kW supposedly and with 7 hours of charge time I could get say 18.2kWhr stored.
I plan to get a second 9.5 battery in Feb when VAT is dropped and I suspect for about 6m months per year I will be pretty much grid import free as I have 27 panels.
Charge both during day (plus a bit of export to pay for winter).
The extra battery is really to help in winter and just fill the batteries on Eco7 off peak to see me though each 24hr cycle.
Currently on the darkest days I have to import about 5kWhr at day rate from about 18:00 as the battery is flat

SteveCook .... Interesting what you say - but will a 2nd battery cost in for you? It seems only a few months are you importing 5kwh. The majority of the year you are probably OK

quarkrad
Hi Yes i think a second battery will be about £3k. I know savings not too great, but cost of power will rise I am sure.

When my smart meters worked I was on Flux and could get really good peak export rate, so with 2 batteries I should be able to do a peak dump for 3 hours every day in sunny months and still have enough battery power to run without import. I am waiting for Octo to fix meters though! 45 months so far!

Another benefit I will get from another battery is I have EPS running permanently on fridge, freezer, boiler, smoke alarms, burglar alarm, router, sky box and lounge power, so in the event of a power cut we can sit in the warm and watch TV, so more storage the better/longer.

I'm trying to find 'a simple' way of estimating my 'high rate' consumption. I've looked at the daily inverter detail but the figures do not really add up. My battery tends to run out about 18.30 so I downloaded the consumption readings (copy & paste to spreadsheet) from 18.30 on, but the total figure was way way out compared to the graphs from the Givenergy Reports. Closer inspection showed there was a few high figures in the inverter detail figures. I think what happens is there are some very short spikes that are recorded. I have examples (that is specific days) when my overall consumption might be 35kwh but when I look at the inverter data for that day between 18.30 and 12.30 it can add up to 49kwh. Mad - except if there are these very short spikes (assuming this is what they are) that are recorded in the inverter data but not long enough to effect the overall consumption figure shown in the graph reports.

Try this post. I used it to check my Octo bills.

https://community.givenergy.cloud/d/2881-report-data-download-as-excel-file

quarkrad Yes, as you say, the data is just snapshots of instantanous power. Have a look at the meter data instead - I think those are the cumulative energy figures over time (so energy use between two times is the difference in readings at start and end).