The sun has been out finally and thoughts now turn to the long awaited holidays that we all deserve. With that in mind, I wondered if anyone had any thoughts or recommendations on suitable settings while leaving a solar/battery installation unattended for few weeks.
Our current configuration is 5.1 kWh solar with a 9.5 kWh battery coupled with Octopus flux.
Instinct says just let it run as normal,
Your batteries will get to 100% quicker as your not using any extra power, and if you are getting paid for export then you’ll just make a bit more.
There is an argument that you could reduce your battery full from 100% down to maybe 50% so you start exporting earlier.
And to do that I would just need look how low your batteries are first thing in the morning and then set your battery full % to that amount whilst you are away.
then change is all back either the day before you leave your holiday or as soon as your back.
I also have the exact same install as you :-) - so would be interested on what you did as I am also soon to go on holiday.
You have just given me another advantage of Intelligence Octopus Flux that I have been on for 6 days. I would feel happy just leaving octopus to manage the battery.
Otherwise I think I would reduce the max SOC and just leave it to charge and export.
We have an AIO and 10.6kw solar hooked up to HomeAssistant using an add-on called Predbat. It works out the best model to reduce cost/increase profit using your GivEnergy variable (import and export) rates, solar forecast and daily use to develop a plan that is updated every 5 minutes. There is also a holiday mode where the historic use is bypassed to get a better prediction/plan.
Highly recommend taking a look. An incredible bit of software.
Hi John,
We went away the other week and I had just the same question.
I am coming to the conclusion that the simplicity of Octopus Flux is the answer and you can do as armstrng2 suggests - “run as normal”…
…Octopus Flux has 2 rates that are good to use:
15p/kWh to import at cheap rate and export during the day
25p/kWh to import during the day and export at peak rate.
There are also 2 rates to avoid:
5p/kWh to export at cheap rate
35p/kWh to import at peak rate.
(For simplicity I have rounded the above to the closest penny)
Based on this simplification, you can set a ‘universal schedule’ from the inverter remote control page on the cloud user interface:
ECO mode as a default
charge to 100% at cheap rate
discharge to a ‘low %age’ in the evening peak rate
Setting this ‘low %age’ is a little bit suck it and see, I aim at about 10% to 20% so that I don’t risk running out before 7pm and so importing at 35p/kWh. It doesn’t matter too much if the %age is higher - you just miss out on exporting at 25p/kWh and then importing at 25p/kWh after 7pm - as long as you empty the battery between 7pm and 2am, when cheap rate starts and you can fill your boots with 15p/kWh electricity.
I think that a more sophisticated control strategy (eg using an external control computer like Home Assistant) would be able to take account of the fractional penny differences in rates and perhaps start considering issues like weather forecasts etc, but to a 1st order of magnitude the above works with one caveat…
…you can only really use ‘end time’ to exit discharge mode - the system then returns to ECO mode. It seems that if you hit the % SOC lower limit then the battery is disabled until you hit the ‘end time’ and only then does the system return to ECO mode. This is a shame as if the behaviour at % SOC lower limit was also to return to ECO mode then you could run the battery much closer to empty/4% without risk of importing at 35p/kWh. Eg while we were on holiday our night time electricity consumption was ~100W, so between 7pm and 2am that is 0.7kWh - this would work well - HOWEVER, I use time as the endpoint to avoid the lower SOC% and battery disabled mode and so I was typically going into the cheap rate/charge period with about 15% to 20% battery charge remaining (ie I could have sold another 1 or 1.5 kWh at 25p/kWh and replenished at 15p/kWh).
My take is that, during the summer, other than for a few extremes (like holiday or high consumption during the peak rate) this works well and gets me to within ~10p/day of the optimum. My worry is that during the winter then this will be much more unpredictable. My system was installed in March this year, so this is just my theory until we hit winter…
…my understanding from informal communication with GivEnergy is that the ‘disabled battery mode’ is a known issue and I hope that it will be resolved before the winter. If the system returned to ECO mode when the lower SOC %age limit was reached then I think that the schedule could be easily set once for the whole year, including holidays, and you would be well within 10p/day of the optimum use of Octopus Flux (ie within £36.50p of the optimum).
Enjoy your holiday:)
Dave
Thanks Dave, a well considered approach which I will try to apply. The setting that I’ve struggled with is the limit on discharge. I think that when I set a moderate %age limit on discharge during the peak period it also restricted how the bettery operated after the discharge period. In that because the limit had been reached then the battery did not fulfill household demand.
It may be that I needed to switch the battery into a new mode of operation.
Hi John,
I struggled with the same issue. I ended up with 3 x 30min discharge periods:
-each with progressively lower SOC %age limit (70%, 40% and 10% I think).
-mostly the discharge periods are short enough that I never hit the SOC % lower limit (this takes a bit of trial and error)
The approach is not very robust, eg:
-gloomy days (like yesterday in Lancashire)
-high demand (eg cooking and washing during the peak period).
However, so far, since March it has not been too bad and is the best I can think of until the ‘disabled battery issue’ is resolved.
The thing that saves you is the Octopus Flux tariff - if you run your battery close to empty then you maximise selling electricity at 25p/kWh and end up buying some between 7pm and 2am at 25p/kWh (ie makes no difference) and if you don’t manage discharge/sell everything possible at 25 p/kWh in peak then you don’t need to import/buy at 25p/kWh between 7pm and 2am.
Good luck and hopefully you can relax on your holiday leaving your solar system to earn you a few £s - it won’t be optimised, but it will not be too far from optimum.
Dave
Hi, I have a system similar to yours with everything for Predbat set up. But I’m wondering myself, under the smart tariff on the GE dash, there is a button to ‘stop automation’. Should I be checking that to prevent conflict between pred and Octopus?
My system is a 15kw array (maxing 10.5kw inverter during peak) and a 13.5kw battery. We use a fair bit, but even with the hot tub running, we get through the nights in summer with 40-50% remaining on the battery. is ‘Intelligent’ still the best tariff here?
I should correct that… we were getting through the night with battery, now, of course 'intelligent has just been doing its thing.
Hi,
I just checked my mobile GE app and it says:
Automations
Currently on: none
For both imports and exports.
