June 7, 20223 yr I have an Axpert/VM-3000 inverter, panels, lifepo4. As soon as it starts getting light in the mornings, about 1.5 hours before the panels can produce usable energy my inverter switches over to solar/battery, same in the afternoon, the last 1.5 hours of daylight does not produce much energy. I don't want the inverter to use battery power. It must use solar when enough is available to power the load, and switch to Utility when PV input falls below what's needed. I don't want it to use battery power as it adds cycles on the batteries. Where do I go from here: Add a timer switch on the PV input wires, and only connect the panels to the inverter during the hours I know they can power the load? That leaves the issue of cloud cover during those hours when it will use battery till "Back to grid V". Back to grid is 25.5V max on my inverter, so it will drain a lot from the batteries before switching back. I can write a small program on a PIC or Arduino to look at the batt V, or pull data from inverter to see when PV W fall below a certain threshold, and disconnect the panels to force it back to grid. In case of cloud cover it can retry to run from panels in x minutes to see if enough power is available? Many options. What do you think I should do?
June 9, 20223 yr Hi @DJ1 ok , can you provide an image of the identification label on the side of your VM inverter . ?
June 9, 20223 yr @DJ1 Great to see you have some ideas. This seems to be how these inverters operate. Mine is doing the same. Looking at the extend of the problem I rate it not so serious to "loose" 37Wh x 2 daily as this is the self consumption of the inverter. As a percentage of say a 2400Wh or larger battery it is a very small value. Normally during clouding the PV would produce over 25W so it should not cycle the battery. It is due to this reason that a minimum size of PV is indicated in the specs.
June 10, 20223 yr Author For now I'm running MultiSIBControl app with 2 rules at 5 minute intervals. 1) Switch to Grid if: Grid is available AND Battery SOC is below 99% AND Solar input is below 100W 2) Switch to solar if battery SOC is above 99% between 08H00 and 16H00 The last 2 days it worked well to prevent battery power being used.
September 16, 20223 yr 19 minutes ago, DJ1 said: In the end I built this to measure and control everything... Hats off to those DIY skills! 👍 Edited September 16, 20223 yr by jumper
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