A long explanation;-)
House i Finland, NordPool day-ahead electric price (floating)
Onsite is an old fully upgraded MultiPlus 12V 2kW with 600-800Ah LFP-bank with CCGX and mobile-internet connection.
Tested-> DESS works via vrm-portal and removed again. I tried to look at DESS and lost my mind totally, no chans to understand how to configure settings. And rules are clear, no greenwashing allowed
No solar, no generator, grid stability is excellent
I try to figure out how to do changes in MultiPlus for avoiding extreme elect.prices this winter by avoiding grid use when price are thru roof, always cheaper to charge batterybank at night
House:
Heatpumps 24/7 on, stupid versions. (Cut power and they stay in waiting mode until manually on again)
Instead MultiPlus providing “grid” 24/7 to them → this works perfect
Oilburner- furnace is connected to a 12V800W MultiPlus with 400Ah LFP:s
Question:
But how to easy way give Multi a relay-order to ignore grid with high price hours and delay charging to batterybank at night from a Shelly connected to NordPool/ Entso-E day-ahead prices?? Use of generator relay??
@Mekaniker as a really simple solution you could have the autogenerator start relay control a contactor on the input to your multiplus…
I am guessing the pricing variation follows a pattern that could be programmed into the auto generator start parameters. That could also follow a trigger based on time and state of charge. For instance, if the battery SOC ever gets so low as lets say 5%, allow mains on the Multiplus. If the battery SOC is below lets say, 80% between 2am and 5am, allow mains on the mltiplus. This means that between 2am and 5am if the SOC is below a certain level the cheaper power will be used to charge the batteries. If the batteries get very low at any time, the batteries will use mains to charge them.
Of course if you want to manully apply mains you can by manually “starting the generator”.
I know the relay, with manual/ scheduled switch it isnt possible to have grid assist if necessary
A scheduled on and off is possible but not delayed charging
Why a delayed charging?
With floating day-ahead prices on electricity it is a serious money-saving every day: Buy at night to batterybank and use from batterybank at day;-)
But I have a more serious problem now:
Installed DESS again and now I have a crippled MultiPlus, undervoltage alarms blocking use totally…
I got a message from a forum-member here and it seems to be a serious bug somewhere in software??
All firmware are on last versions
Must try to find a answer to that issue tomorrow
Depends on how good your programming skills are.
What I implemented is roughly to keep track of the amount of energy in my batteries and the average price, and with an assumed efficiency number, charge when it is cheapest and the price is lower than my “battery price”, and discharge when it is higher.
Setting the ESS to discharge, idle, or charging is easy, just set the “minimum SOC unless grid fails” to 20%, the current SOC or 100% respectively, via modbus.
This is of course basically what DESS in “green mode” should do, but I agree with you that it still needs development.
Fi is chosen as start, chose a another and compare;-) Every day at 14:00 we get new price to live with. It is also the price for export to grid from ex. solar or from battery if its allowed
And why that low just now: Someone have fun to cut our grid-cables to Estonia
