Hello there
Since some time now we’re running a few residential systems with DC Coupled PV into an ESS with about 30kWh of storage. All are in the very common situation with static time of day based high and low tarrifs, commonly refered to as Day/Night tarrifs, and a feed in reward that is 25% below the low nightly tariff.
Some times we see the situation in the acompanying screenshots where in the first period of pv power coming in the pv and even part of the battery capacity are beeing fed into the grid.
That battery capacity had better been used to cover more of the nightly consumption as savings would have been 25% above the feed in reward.
Is there a way to influence / optimize that?
Basically our primary target is to cover 100% of the 24h consumption and have feed in as a secondary objective only for excess solar power.
Cheers and thanks for your fantastic products Victron Team.
Henk
I can confirm a kind of similar behavior of my DESS system at the very beginning of PV-in on some days. The system reacts after a relatively short time and starts to charge the battery (less than an hour).
I see a grid consumption at night in your chart. Is it really the case, that your battery cannot cover that load due to low SOC or does your DESS behavior show the same effect as my one does? Consuming power from grid at night, although the battery would have enough SOC to cover the load?
My battery Capacity is large enough to cover just about 24h of consumption.
That feed in from battery cannot make any sense as long as it leaves some time open relying on grid import.
Of course DESS needs to prioritize. But only if the entire Dusk to Dawn period is covered with battery capacity and the battery is full should feed-in of excess Solar occur.
The 24h Fixed Feed-in Tariff being lower then the low purchase tariff would make anything else cost more.
I see a similar behavior on my side. From my observation, DESS sets a high target SOC (50% or more) at night for no obvious reason. Although my battery is still over 50% in the morning, the high target SOC lead to grid consumption at night and even grid to battery charging. Since days, my battery never drops below 50% but I import from grid, even in times with high costs.
