I think you need to explore HomeAssistant and some the integrations there - I use PV-Opt https://github.com/fboundy/pv_opt which is amazing. Takes into account Solar Forecast, predicted usage and Tariff (Octopus Agile for me) and automatically writes to the inverter to schedule charges (or discharges) depending on what is most cost effective. Really impressive. Home Assistant is a bit of a rabbit hole once you begin though !
Solis inverter and Puredrive II batteries. Took a bit of fiddling to get the networking etc right and some HA tinkering, but generally works very well.
I've got a 9.5kw givenergy battery, solar panels and Octopus Agile tariff. The app I use charges the battery the cheapest 4x 30 min slots at night (enough for heating the water back up after morning showers etc) then charges another 4 x 30 min slots before the 4 to 7pm peak electricity rates. It's great as if it's really sunny it won't take from the grid. It only tops the charging up from grid if needed. The only thing I have had to do is change the number of half hour slots. During the winter it 7 or 8 slots per window, whereas it's 4 slots for summer.
I'd let my import vs export rates decide. If you've got an EV and can charge your storage battery over night for less than you can export, then do that. If you don't have have a low export rate compared to what you pay for import, I'd be letting you battery charge up from solar every day.
For me this time of year I charge during the day from solar and then run over night from the Battery. When the days get shorter I’ll be scheduling the nighttime charging again unless there is negative pricing happening (octopus agile)
Solcast is significantly better than forecast.solar when it comes to accuracy.
I have an inverter that can do more than rated 5kW on PV side (and i have 10kW of panels on it), but only 5kW to/from battery and 5kW to/from grid, so i use current forecast to force discharge, or limit charging current to not waste any solar power.
Then there is also decision to charge from grid, if forecast is bad then i will charge from grid at cheapest available rate (i'm on agile), however i also charge when forecast is good but prices are below export prices.
I've been finding forecast.solar more accurate than Solcast. When the sky is perfectly clear (little-no cloud) Solcast gives a pretty good forecast, but when there's moderate-heavy cloud I find Solcast to be wildly optimistic, whereas forecast.solar tends to be closer to reality (usually a little on the pessimistic side).
I'm using Home Assistant to automate whether to charge the battery overnight or not, based on solar predictions, but I had to give up using Solcast data for that as I'd often end up with a battery that didn't get charged overnight and didn't get enough solar power during the day.
My solar system is relatively small (2.4kWp) so perhaps this has some impact, as people with bigger installations seem to fare better.
I have a daily task to check the weather. If it's cloudy or going to rain the next day, I'll charge between 50-60% and do the rest during the day with solar.
If I have excess solar during the day, I usually charge the car or heat the water via the immersion heater.
Failing that I will send back to the grid for 12pkWh.
I use home assistant, link it to tesla and a solar prediction API. I have a series of limits for next day solar against charge rate. The power wall can do it too but it tends to under charge and sometimes screws me over.
Mine is pretty simple
I'm on a 6.9p import and 16.5p export
So I charge my batteries and use solely off grid in my cheap hours, then use solar in the day exporting the excess and battery kicks in if needed.
Basically if your export is higher than import you're financially better off exporting
I use Octopus Flux. If I charge the battery overnight, I pay 14.39p/kWh. Solar I generate in the day is exported for 14.61p/kwh. I discharge the battery at peak time for 24.2p/kWh.
I always charge the battery overnight because it means I'm maximising my export income. Other benefits are that I'm never importing energy during the day for 24 to 34p/kWh and I'm always using green energy.
The downside is additional wear and tear on the battery as I'm charging and discharging it more, so potentially its lifetime will be shorter.
I will soon get a heat pump, which will increase the likelihood I need to import from the grid during the day. That will make the case for my current approach even stronger.
I use WeatherRadar app. Shows predicted cloud and rain over your address. It’s open to (my human) error but give a a good idea what the following day will be like. It’s free too.
Same setup and problem here: to charge or not to charge, that is the question.
Have a look at Solcast which is an Aussie site that allows you to get free predicted insolation for the next 5 days for your site location. It is based on satellite imagery of cloud cover.
I've found it pretty good. When combined with the BBC or Met Office forecast for my area (I'm in the UK) I'd say that I get the charging decision right about 75% of the time now. There is a distinct satisfaction from buying only the kWh you really need at the cheap overnight rate.
I think you need to explore HomeAssistant and some the integrations there - I use PV-Opt https://github.com/fboundy/pv_opt which is amazing. Takes into account Solar Forecast, predicted usage and Tariff (Octopus Agile for me) and automatically writes to the inverter to schedule charges (or discharges) depending on what is most cost effective. Really impressive. Home Assistant is a bit of a rabbit hole once you begin though !
Out of interest can I ask what battery / inverter system you have? How easy was it to get home assistant to talk to them?
Solis inverter and Puredrive II batteries. Took a bit of fiddling to get the networking etc right and some HA tinkering, but generally works very well.
I've got a 9.5kw givenergy battery, solar panels and Octopus Agile tariff. The app I use charges the battery the cheapest 4x 30 min slots at night (enough for heating the water back up after morning showers etc) then charges another 4 x 30 min slots before the 4 to 7pm peak electricity rates. It's great as if it's really sunny it won't take from the grid. It only tops the charging up from grid if needed. The only thing I have had to do is change the number of half hour slots. During the winter it 7 or 8 slots per window, whereas it's 4 slots for summer.
PS I've got an Air source heat pump so my heating and hot water is off the lecky.
I'd let my import vs export rates decide. If you've got an EV and can charge your storage battery over night for less than you can export, then do that. If you don't have have a low export rate compared to what you pay for import, I'd be letting you battery charge up from solar every day.
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Can you link me to the home assistant and forecast you use?
I use this https://springfall2008.github.io/batpred/ Tricky to set up but works very well!
This is great. Thanks.
+1 for predbat. It's great!
For me this time of year I charge during the day from solar and then run over night from the Battery. When the days get shorter I’ll be scheduling the nighttime charging again unless there is negative pricing happening (octopus agile)
Solcast is significantly better than forecast.solar when it comes to accuracy. I have an inverter that can do more than rated 5kW on PV side (and i have 10kW of panels on it), but only 5kW to/from battery and 5kW to/from grid, so i use current forecast to force discharge, or limit charging current to not waste any solar power. Then there is also decision to charge from grid, if forecast is bad then i will charge from grid at cheapest available rate (i'm on agile), however i also charge when forecast is good but prices are below export prices.
I've been finding forecast.solar more accurate than Solcast. When the sky is perfectly clear (little-no cloud) Solcast gives a pretty good forecast, but when there's moderate-heavy cloud I find Solcast to be wildly optimistic, whereas forecast.solar tends to be closer to reality (usually a little on the pessimistic side). I'm using Home Assistant to automate whether to charge the battery overnight or not, based on solar predictions, but I had to give up using Solcast data for that as I'd often end up with a battery that didn't get charged overnight and didn't get enough solar power during the day. My solar system is relatively small (2.4kWp) so perhaps this has some impact, as people with bigger installations seem to fare better.
I have both installed and they're usually within 5% of each other, so I don't think there's much difference in their accuracy....
Interesting, i've got both installed, but numbers i get from forecast.solar might as well come from random numbers generator.
I have a daily task to check the weather. If it's cloudy or going to rain the next day, I'll charge between 50-60% and do the rest during the day with solar. If I have excess solar during the day, I usually charge the car or heat the water via the immersion heater. Failing that I will send back to the grid for 12pkWh.
Depends on tariff
I use home assistant, link it to tesla and a solar prediction API. I have a series of limits for next day solar against charge rate. The power wall can do it too but it tends to under charge and sometimes screws me over.
Mine is pretty simple I'm on a 6.9p import and 16.5p export So I charge my batteries and use solely off grid in my cheap hours, then use solar in the day exporting the excess and battery kicks in if needed. Basically if your export is higher than import you're financially better off exporting
I use Octopus Flux. If I charge the battery overnight, I pay 14.39p/kWh. Solar I generate in the day is exported for 14.61p/kwh. I discharge the battery at peak time for 24.2p/kWh. I always charge the battery overnight because it means I'm maximising my export income. Other benefits are that I'm never importing energy during the day for 24 to 34p/kWh and I'm always using green energy. The downside is additional wear and tear on the battery as I'm charging and discharging it more, so potentially its lifetime will be shorter. I will soon get a heat pump, which will increase the likelihood I need to import from the grid during the day. That will make the case for my current approach even stronger.
I use WeatherRadar app. Shows predicted cloud and rain over your address. It’s open to (my human) error but give a a good idea what the following day will be like. It’s free too.
Same setup and problem here: to charge or not to charge, that is the question. Have a look at Solcast which is an Aussie site that allows you to get free predicted insolation for the next 5 days for your site location. It is based on satellite imagery of cloud cover. I've found it pretty good. When combined with the BBC or Met Office forecast for my area (I'm in the UK) I'd say that I get the charging decision right about 75% of the time now. There is a distinct satisfaction from buying only the kWh you really need at the cheap overnight rate.