Discharge battery before peak solar

[BVGC]

I'm not sure if this is common but it seems that the way my inverter (luxpower) is setup is that it can outperform its limit if it is able to charge the battery at the same time as exporting.

I have a 7kw inverter with a 10kw PV system & 10kw battery. I've noticed that if the battery is charging during peak solar, i can actually get 10kw of solar because 3kw can go to charging the battery and 7kw can be exported. If the battery is full then i can only get 7kw solar which is immedaitely exported. Is there a way in predbat to intelligently automatically discharge my battery in the morning, prior to peak solar should the expectation be for PV input >7kw? This way I can maximise my throughput by charging the battery to full whilst also exporting to reduce PV lost due to clipping.

Thanks

[BVGC]

I think I’ve since discovered that this is already supported. I didnt realise because i set my solcast solar estimate to only perform with low efficienty (80%). This was to compensate for the fact that i get shading in the afternoon. Once i changed this to 100%, the plan appears to be managing the battery as i would have hoped.

Is there a way to penalise the solcast forecast specifically for a few hours during the day when shading is expected but to have it at normal levels for the remainder of the day?

[CossieRob]

In the Solcast integration, when you click configure there is an option to set dampening. I'm fortunate in that I don't suffer but it may be an option.

[BVGC]

Perfect thank you

[springfall2008]

You could also try the Predbat auto solar calibration

[BVGC]

Thanks just seen your youtube video. I will give the auto solar calibration a try

[BVGC]

predbat_debug.yaml.txt

I tried this out today (predbat auto solar calibration). Initially the plan looked sensible - It would charge to capacity overnight and then discharged to 65% from 10am onwards. However, what i found was that once the solar output started to exceed 7kw (my inverter limit), the system stayed capping out at this level. The battery refused to be charged and would just export a trickle (or nothing at all) alongside the PV solar of 7kw. From what i could tell this was because, in the Predbat plan, force discharge was still enabled. I note in the plan that, whilst the state is "EXP", it still expects the "SOC%" to increase which isnt happening. I have "inverter_can_charge_during_export = false" so not sure why its assuming the battery will charge. Once i switched predbat to monitor, and disabled force discharge, the system instantly increased PV to 8kw (5kw to battery charging, 3kw export).

Also to note is that there is a switch on my inverter which predbat doesnt seem to touch called "Charge Last". If i enable it then my solar instead, with 8kw output, sends 1kw to battery and 7kw to export. This seems like a more preferable solution during the periods of peak solar as otherwise the battery could fully charge again within the hour meaning i'd be getting clipped once more. I presume it is the effect of this which predbat is trying to emulate by keeping the export state enabled?

I don't know if this is something specific to my inverter that means when force discharge is enabled, the battery cant charge at all even if solar exceeds inverter limit. Is there a way during this time for predbat to no longer force discharge to allow the battery to charge (and also to prioritise exporting through charge last)?

Thanks

[BVGC]

I decided to use automations to create a hacky solution for this during summer months but if anyone has a more robust solution im all ears. Naming is specific to the luxpower inverter:

10:00am - turn on predbat read only mode, Turn off Inverter AC Charge Enable, Turn on Inverter Charge Last
10:01am - If Inverter Battery % >60% Turn on inverter forced discharge
11:00am - Turn off inverter forced discharge
16:30pm - Turn off Inverter Charge Last, Turn off predbat read only mode

[springfall2008]

I just checked your debug yaml and 'inverter_can_charge_during_export' is still True.

Did you put

inverter_can_charge_during_export : False

Into apps.yaml?

[BVGC]

Thanks for your reply.
Yes I did change this later although it didnt generate any charge freeze periods and plan looked similar. Does predbat use any clear sky solar data? In my plan below, predbat is set to export between 13:00 and 14:30. At first glance this seems fine because the solar expected to be generated in these half hour periods is less than my inverter limits. However, i will still end up getting clipped here because there are likely to be moments when the skies are clear so my inverter is generating 9kw not 6kw (even if it average 6kw over the course of the 90 minutes). This will mean my solar will underperform expectations during this period.

If predbat was able to model clear skies, then for periods where max possible output is greater than inverter limits, it could ensure not to be exporting from battery whilst ensuring charging the battery is lowest priority. Is this something that is possible? I note that forecast.solar does provide clear skies data although only for the professional 70 euro/year model. I doubt this level of accuracy is required though as it would probably model well enough if it assumed that clear skies for the months of April to September to assume clear skies between 11am and 5pm produce > inverter limits

[gcoan]

Predbat uses the solcast 30 minute forecasts, and by default a blend of the PV50 and PV10 forecasts, i.e. the 10% (worst case) and 50% (generally likely) forecasts.
You can change this if you want or change the weighting of the forecast used.

Solcast on the hobbyist account doesn't give clear sky data, but to be honest I doubt how much extra accuracy and generation that would give you. At the end of the day it's just a forecast and the reality never 100% follows the forecast.

BTW, on your original comment, rather than putting predbat into read only mode and controlling the inverter yourself why not use select.predbat_manual_force_export to set a series of forced exports in the morning. It's what I do to ensure my battery is empty and it can be used to reduce clipping. I also (via automation) control the charge rate during the day so it doesn't fill up too quickly