I am running a 3-phase MultiRS setup managed by VRM DESS.
The system has planned the feed back solar energy to the grid in the morning while prices are still reasonably high, charge the battery from grid and solar at the three hours with the lowest prices, feed excess solar back to the grid when prices rise again in the afternoon and empty the battery in the evening at the best prices… So far all seems well.
However while charging the battery at the three lowest price hours, I notice that my MultiRS throttles the MPPT down to be able to draw more power from the grid. Prices are low but still well above zero.
Manually limiting grid current (if needed all the way to zero) allows the solar panels to go up to full power again.
I would prefer my solar panels to only be throttled at tarifs below zero, or to prevent overcurrent situations. Am I missing a setting somewhere? Is there an easy way to manipulate this from Node-Red without having to fully create a DESS in NodeRed?
I am very pleased with the MultiRS performance but figuring out how to fully tweak ESS/DESS from NodeRed is somewhat of a challenge.
we recently discovered this behaviour and a fix is being worked on.
It requires some changes, so we cannot say when this will be released.
For the time you could only limit the battery charge rate in DESS to a value that would allow your multirs to utilize 100% dcpv and only pull the difference from grid. Or if dcpv is enough to saturate the mpptrs output, place a grid2battery restriction during the questionable hours and DESS will schedule accordingly to not request additional power from grid.
Given that I can detect the unwanted behaviour from the "MultiRS | MPP operation mode " in NodeRed I chose to create a rudimentary feedback loop gradually lowering my AC Current Limit while the MPPtracker shows ‘1 - voltage/current limited’ and gradually raising my AC Current Limit if it is operating at full capacity…
Obviously this limits all three of my MultiRS’s because the AC Current Limit is a global setting, but that is a small price to pay compared to wasting solar from my roof while buying energy from the grid
On a sidenote:
Given that the MultiRS can obviously throttle the onboard MPPT an easy way to actively control this throttling from NodeRed for optimising revenue by charging the battery from the grid instead of the MPPT in case of well below zero energy prices is on my wishlist for the future…
A simple on/off switch for the onboard mppt while still allowing charging from the grid could work about as well for me, I guess…
