I'm having my system installed this week but an export limit has been imposed at 3.68kW so how I manage my generation is going to change.
Initially I was having 28 panels, FoxKH10.5 inverter and Fox EP11. My plan was going to be charge up the battery at night and send as much solar back to the grid and let the battery fill in the gaps.
Now the DNO has capped the inverter size to 6kW and export at 3.68kW so panel amount has had to reduce for the inverter size to 22 panels.
Now my question is I don't think my original plan will work as I won't be able to export fast enough. In the summer months if I fill the battery to 50% is it possible to set it up so as the system exports at the 3.68kW whenever charge is above 50%? I've read about the feed in work mode, but my question with that is does the battery discharge if solar generation is below 3.68kW?
And will this work or am I still unlikely to be able to export fast enough? Second battery required?
If you run in Feed In workmode the priority for PV generation will be to House first, then export then battery (if you exceed the export limit).
So if you have an export limit of 3.68kW set then everything above that once house load is accounted for will be used to charge the battery.
If the solar generation is below 3.68kw the battery obviously won’t get charged but you could charge overnight as you originally suggested with a MaxSoC of (say) 60% set - then you would start the day with a 60% battery charge and any spare above your export limit would go to the battery.
On a dull day - let’s simply say zero solar your battery would be used during the day to run the house and would very likely run out before you get through the night.
On a bright sunny day you’ll be exporting flat out and will have charged the battery by mid morning at which point unless you can use it in the house heat pump, EV charger, water heater etc.. the inverter will clip (which will be a massive waste)
Because of your export limitations having a second battery would be more than helpful as would having a dynamic approach to charging - either based on solar forecasts (or at least a seasonal approach such as summer don’t grid charge over night, autumn grid charge to 60%, winter grid charge to 90%)
Not sure i’ve answered your question fully but fire away if you need more answers.
So if you have an export limit of 3.68kW set then everything above that once house load is accounted for will be used to charge the battery.
If the solar generation is below 3.68kw the battery obviously won’t get charged but you could charge overnight as you originally suggested with a MaxSoC of (say) 60% set - then you would start the day with a 60% battery charge and any spare above your export limit would go to the battery.
On a dull day - let’s simply say zero solar your battery would be used during the day to run the house and would very likely run out before you get through the night.
On a bright sunny day you’ll be exporting flat out and will have charged the battery by mid morning at which point unless you can use it in the house heat pump, EV charger, water heater etc.. the inverter will clip (which will be a massive waste)
Because of your export limitations having a second battery would be more than helpful as would having a dynamic approach to charging - either based on solar forecasts (or at least a seasonal approach such as summer don’t grid charge over night, autumn grid charge to 60%, winter grid charge to 90%)
Not sure i’ve answered your question fully but fire away if you need more answers.
Thanks Dave, it sort of answers my question. In feed in mode, if the solar is below the 3.68 limit what does the battery doing?
In an ideal world what I'd like to be able to do is have a steady 3.68kW export regardless of where it comes from, effectively using the battery as a generation buffer.
In an ideal world what I'd like to be able to do is have a steady 3.68kW export regardless of where it comes from, effectively using the battery as a generation buffer.
In Feed In mode if the solar is below 3.68kW the battery will be idle, any solar will meet the house load and what’s left will go to the grid - if the PV generation falls below the house load the battery will discharge to fill in the house load but it won’t be used for export.
What most people do is to use the scheduler to charge the battery first in the morning and export the remainder and then later in the day switch to a Force Discharge mode which uses a mix of PV / Battery to export your 3.68kW.
Ideally you would set up a home assistant which would allow you much more granular control of what is happening, using solar forecasts to blend when you charge and when you discharge the battery to make sure you use all the excess solar - but as mentioned above using the scheduler, particularly with time of use tariffs like Octopus Flux you’ll get close to what you are after.
What most people do is to use the scheduler to charge the battery first in the morning and export the remainder and then later in the day switch to a Force Discharge mode which uses a mix of PV / Battery to export your 3.68kW.
Ideally you would set up a home assistant which would allow you much more granular control of what is happening, using solar forecasts to blend when you charge and when you discharge the battery to make sure you use all the excess solar - but as mentioned above using the scheduler, particularly with time of use tariffs like Octopus Flux you’ll get close to what you are after.
So if the battery is set to force discharge at 3.68kW and solar generation is say 1kW, will the battery discharge at 2.68kW and then the 1kW from the solar feed in?
Is there any guides on the home assistant side of things for what you're suggesting? As it's definitely something I'd be interested in.
Is there any guides on the home assistant side of things for what you're suggesting? As it's definitely something I'd be interested in.
Yes that’s correct.
If you go to the videos section of the forum you’ll see a load of youtube videos by William Eccles, if you go to youtube and look at his channel their are videos there that explain how homeassistant can be setup and what it can do (which is essentially real time control of the inverter).
If you go to the videos section of the forum you’ll see a load of youtube videos by William Eccles, if you go to youtube and look at his channel their are videos there that explain how homeassistant can be setup and what it can do (which is essentially real time control of the inverter).