Kia ora all, I have an off grid EasySolar II GX set up with AGM batteries and a PV inverter on ACout 1 of the EasySolar. The EasySolar has about 3 kW of panels facing morning sun and the PV Inverter has 3 kW facing the afternoon sun.
The EasySolar uses Frequency Shift Power Control to choke off the PV Inverter when the batteries are full.
This works rather well in that it provides a long period during the day with enough production to charge my EV (10 A, 230 V).
What could be better is that the EasySolar seems to favour powering the AC circuit by inverting from the battery, generating heat in itself while choking back the more efficient PV inverter.
Is there a way I can tell the EasySolar to prefer using the PV Inverter to power AC circuits?
Thanks
Graham
The trouble is the system also has to protect the batteries, so it is safer to have the PV inverter ramp down.
You can do a more clever control using node red so it runs more, but we had to add an energy meter to make that happen more smoothly.
Thanks Alexandra.
We have a BMV700 monitoring the battery. Does that qualify as an energy meter?
No, mine also has a BMV but we needed something for the bigger loads specifically.
So you need an AC meter for this idea. We are currently using a shelley to monitor the loads then a calculation done in node red with modbus control to ramp up or down. (Frequency shifting still works).
That’s great, I love Shellies, all my lighting and a few power outlets are Shelly-controlled. Are you able to share your code to do that please?
No, it is an SMA SunnyBoy HF3000- quite an old model. It has RS485 ports and it can be controlled over them by YASDI, but I haven’t probed far into that.
@spicedreams
Sorry i didn’t reply. The i use the smart meter information then send commands via modbus to the fronius. Wouldn’t be possible with your SMA.
The only thing i can think of to make the sunny boy work for AC loads is to use its energy meter on the output of the inverter to orevent it feeding back but then that means battery charging may become an issue from AC PV.
Unless it has some kind of i out to tigger to stop feedback on command? I am not familiar with the units.
Thanks Alex @lxonline
The SunnyBoy uses what seems like “industry standard” AC frequency control to stop it putting power out when not needed. When the Multiplus gets close to full battery and no load, it increases the frequency of the AC Out by 1-2 Hz. The SunnyBoy responds by reducing power output at first, then when the change is >1 Hz it stops completely. I think this is ‘factory’ behaviour for the SunnyBoy, all the settings I can see are protected by SMA’s “Grid Guard” which prevents untrained people doing anything that would compromise the public power grid.
I have two arrays of solar panels: “morning” is connected to my SmartSolar, “afternoon” is connected to the SunnyBoy. The slight problem is that the Multiplus tamps down the ‘afternoon’ SunnyBoy in preference to the ‘morning’ SmartSolar even in the afternoon and even with a decent continuous AC load (charging EVs). So if the battery is full the afternoon array is throttled back; the Multiplus has to work to charge the EVs (and gets hot), AC demand exceeds what we get from the morning array, so the Multiplus has to draw from the battery- until the battery gets low enough for the Multiplus to reduce AC Out frequency again, allowing the SunnyBoy to send AC direct to the EVs.
What I would like is for the embedded GX to stop the SmartSolar from overcharging the battery, leaving the SunnyBoy throttled only enough so it can meet EV demand without sending any excess to the battery via the Multiplus. It seems like the behaviour I am seeing is Multiplus-native to protect the battery, whereas the GX could see the bigger picture.
How is your pv assistant set up?
TAB: Assistants
TAB: Assistant Configuration
PV Inverter support (size:799)
*) Restart PV Inverters when the (temperature compensated) battery voltage
becomes lower than 54.00 V.
*) The solar converter will start reducing its output power at 50.20 Hz.
Output power will be reduced to minimum when the frequency is 51.50 Hz.
The converter will disconnect when the frequency is higher than 51.70 Hz.
*) Total installed PV inverter power is 3000 Watts.
Total installed PV panel power is 3000 Watts.
Try adjusting this one a bit lower, see if it helps with things.
I ma surr the sunny boy has a table to help with the choice
Thanks @lxonline . If the SunnyBoy were to reduce its output at a lower frequency, then surely it would cause the Multiplus to reduce the relative input from the SunnyBoy. My intention is to increase the relative input from the SunnyBoy because that is converted into AC for immediate use more efficiently than via the SmartSolar → 48v DC - > Multiplus → AC.
What should I adjust on the Multiplus to swing the balance so the AC comes more from the SunnyBoy, not less?
Yes. So you want the throttle frequency where the sunny boy is working a bit. It will take some tuning.