Hi, I have a system with EasySolar II GX, 48V LiFePo 100Ah battery and one string of 2kWp panels. This operates at 150-170V, so easily handled by the MPPT250/70 of the EasySolar.
The panels are facing south, but in the morning i have shading, so real charging starts after 10:00, thus I am “starving” for energy when activity starts at house.
I thought of adding another mppt at roof, direction SE, where I have little real estate for panels. If I use 1.7m long panels, Voc 37V, Vmpp 31V, wise selection would be to put a string of minimum 3, with a proper controller. But I have no such space up there, neither I want 1500Wp more, for only a slot of morning sun. I’d be happy with even one only panel (400W), which I could fit to the roof.
But one Vmpp 31V would not charge the 48V battery (needs 56V at least, +5V of controller).
I searched for Orion isolated dc/dc controllers, I can only see 12/24V system models.
Can you think of any solution to step up panel’s voltage?
Ideally, it would be mppt and would communicate to rest of GX system. But since it will be of little power (400Wp), at a time that battery surely will be well below top up (07:00-10:00, after this the SE orientation will have very little yield), even an “un-controlled” step up charger, but with mppt, would be acceptable.
TIA
You need to use 2 panels in series with at least 72 cells.
Worth looking for.
Or use micro inverters.
So panels to ac direct.
Yes, thank you for that.
Obviously micro inverter (AC coupled to output of MPII) is the other choice, with some cost concerns.
What brand/model would you suggest? APSystems, Hoymils, Enphase?
As of low cost, but proved interoperability (freq shift) with Victron…
I have no personal experience with any of the micro inverters (wish list items)
There are quite a few guys here on the forums who have mods for hoymiles and cost wise they seem more reasonable.
I guess for you it will come down to budget vs return and sizing
@grfloater
I use 3x HMS-2000-4t, 1x HMS-1000-2t and a HM-600. All are integrated using OpenDTU and Debus-dtu from github. I am happy with the setup.
Alternatively look for Maxeon module with 70 Voc
BR
Bjoern
Hi
I had somehow the same type of study recently to add a bit of power for end of day.
Microinverter or small MPPT with proper panel setup if you can put two panels in series.
Indeed one or two panels with a micro inverter may be a way to go… but I found it to be an incorrect way, implying a more expensive setup, playing with grid setups of microinverters to make them frequency ■■■■ enabled, opendtu, no possible frequency shift while on grid, etc.
Let’s say that I was about to go with it for the technical game this was implying, but honestly, more expensive and not as well integrated as native MPPT.
I ended up with a tiny MPPT 100/20 with 2 panels in series with around 38vmpp each - the DMEGC 500 to 510w currently on the market have a very good fit with this small MPPT. Simple and easy.
If you have only room for one panel, then the micro inverter way is probably your sole option.
Thanks you all!
I cannot easily (or cheap) source Maxeon or DMEGC panels in my area.
Microinverter goes a little pricey and needs hacks (openDTU etc) to be integrated. If I put it, I might leave it “free running” (without VRM) - anyway the yield will be minimum (E-SE).
But I will follow the advice and search for two panels in series, small enough (in size, but with 35Vmpp), and a simple MPPT controller.
I do not seem to have “west” starving, but if the E-SE solution is performing, I might consider two more panels at S-SW (for extra juice for the night). The difference is that at this orientation, there is a very high probability that the battery will be full (from day long insolation), so Victron DC control is a must.