I have a Quattro 5000/48 with 10 KWh managed battery.
I now temporarily use it for back-up in my apartment.
Although there are much cheaper solutions available, I chose Quattro because of its versatility for potential future projects.
Now, I want to connect a charge controller to it, but due to restricted space and other factors, I can only use 2 solar panels which are not too large, e.g. 1722x1134.
I’ll put the panels on my balcony windows (i.e. indoors behind glass) for a temporary setup with as little drilling as possible (ideally - no drilling).
I’ll test self-consumption and ESS scenarios using this setup (yes, I’m aware of anti-islanding protection), I’m not planning to feed energy back into the grid (mostly because of bureacracy).
I’ve searched various models, and they typically come in 400-450W range, with
around 39 V, 14.5A open/short circuit
around 32 V, 13.8A at maximum power point
I then proceeded to select those models (or input their params manually) into MPPT calculator, but it doesn’t suggest anything unless there are 3 panels in series.
Actually, trying various combinations, I wasn’t able to get the tool to recommend the MPPT100/20 model.
By doing manual search, I found out that MPPT 100/20-48V will work for my case and satisfies minimum voltage required to start controller.
I then confirmed it for two models in the Excel calculator (I had to find actual Excel to open it, which was a pain)
The 450 watt module does come close to maximum output current and close to maximum voltage at coldest weather, but realistically it will never happen for me.
Is there an error in the online calculator? Or it simply doesn’t represent the entire model range?
Update: I think I can also go with more expensive MPPT 150/35, but it doesn’t suggest it either.
The problem with only two panels in series is the “low” voltage at the highest temperature.
The MPPT need a PV voltage that is 5V higher than the battery voltage.
Och, halte dich doch bitte einfach raus, wenn du keine Ahnung hast.
Bei steigender Temperatur geht die PV Spannung runter.
Wenn man die Systemspannung mal auf 36V stellt, wird der 100/20 vorgeschlagen mit diesen Werten:
Wobei ich da gerade auch noch nicht ganz nachvollziehen kann wie der Rechner auf den Wert kommt.
Ich komme auf 56,3Vmpp bzw. 67,7Voc ← was zum starten der Ladung ja relevant wäre.
Werde da nochmal nachfragen, wie da die Berechnung im Hintergrund genau läuft.
@articice I’m not sure about the calculations in the background, I will ask the developers.
Yes, but I’m using a managed Pylontech battery, it’s float is at 51V.
Right now it’s fully charged and is at exactly 51.31V, and max I’ve seen historically is 52.45V (although at this point it doesn’t need charging for sure).
So, at 90 degrees, minimum requirement coming from fully charged battery is in range of 52.31-53.45V, which is around lowest PV voltage 53.22V calculated earlier.
It would be kind of bad if during summer time battery got fully charged and then inverter can’t supply extra power because MPPT has shut down.
Thanks a lot for your time!
I will build this and test it out in winter and summer, consider an upgrade to 3 panels.
