Hello everybody,
I have problems with my little off-grid solar system. It has two S-ENERGY SM-255PA8 panels connected in series to a Epever 3210N MPPT charge controller and a 12V 70Ah AGM battery is being used. Load connects to a 500W inverter. The solar panels are used, I cannot tell how old they are.
The panels have the following ratings: Pmax = 225W; Voc = 36.6V; Isc = 8.25A; Vmpp = 29.7V; Impp = 7.6A.
Although they are connected in series and in unobstructed, pure sunlight, the charge controller displays a solar voltage of around 16V and the power goes to a maximum of around 100W (a load of around 250W was connected). The first time i connected the system, I once got around 250W at 36V with two panels in series, then it dropped quickly to the 16V with a complete cut off between that shortly. If only one panel is connected to the charge controller, there is no solar power at all, the solar voltage sits at around 13V, 0A current.
I measured open circuit voltage and short circuit current of both panels, which almost matched the ratings on the datasheet on the panels (just a little bit below). Open circuit voltage and short circuit current while connected in series also matched expectations. I tested all bypass diodes on each panel, which were all fine. So the panels seem okay to me.
So i thought it might be a faulty charge controller: i tried different charge controllers (PWM and MPPT, but of the same brand), which all gave the same result. Lately i tried another but brand new single solar panel on my charge controller and it showed, that the charge controller was okay, because it matched the Vmpp of that solar panel with around 36V and could deliver much more power while the solar voltage was always consistent.
Does somebody have an idea, what could be wrong in this system? I am guessing that I am dealing with faulty panels here, but I have no clue what exactly could be wrong with them. Maybe someone can give me some advice on this.
I have problems with my little off-grid solar system. It has two S-ENERGY SM-255PA8 panels connected in series to a Epever 3210N MPPT charge controller and a 12V 70Ah AGM battery is being used. Load connects to a 500W inverter. The solar panels are used, I cannot tell how old they are.
The panels have the following ratings: Pmax = 225W; Voc = 36.6V; Isc = 8.25A; Vmpp = 29.7V; Impp = 7.6A.
Although they are connected in series and in unobstructed, pure sunlight, the charge controller displays a solar voltage of around 16V and the power goes to a maximum of around 100W (a load of around 250W was connected). The first time i connected the system, I once got around 250W at 36V with two panels in series, then it dropped quickly to the 16V with a complete cut off between that shortly. If only one panel is connected to the charge controller, there is no solar power at all, the solar voltage sits at around 13V, 0A current.
I measured open circuit voltage and short circuit current of both panels, which almost matched the ratings on the datasheet on the panels (just a little bit below). Open circuit voltage and short circuit current while connected in series also matched expectations. I tested all bypass diodes on each panel, which were all fine. So the panels seem okay to me.
So i thought it might be a faulty charge controller: i tried different charge controllers (PWM and MPPT, but of the same brand), which all gave the same result. Lately i tried another but brand new single solar panel on my charge controller and it showed, that the charge controller was okay, because it matched the Vmpp of that solar panel with around 36V and could deliver much more power while the solar voltage was always consistent.
Does somebody have an idea, what could be wrong in this system? I am guessing that I am dealing with faulty panels here, but I have no clue what exactly could be wrong with them. Maybe someone can give me some advice on this.
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