ephestione
New Member
- Joined
- Nov 1, 2022
- Messages
- 19
Hi, I am a Jesudom inverter owner, 5.5kW 48V 100A ("VMII plus", a Voltronic clone as many).
I was careless, to say the least, in connecting it with 10x 445W longi panels in series, totalling 480V on open circuit ("heh, the inverter holds up to 500V open circuit, what can go wrong") failing to see how the max MPPT voltage was actually 450V.
Going by the wifi datalogger it reached 470V multiple times during production (only 2 short days of life while actually being loaded, probably went a week with no load at all and just connected to panels before I managed to rewire the apartment), after installation I had it running without battery (was still balancing my EVEs) until one afternoon it just died, error 09; after consulting with the AliExpress vendor (who is always patiently responding to my many questions) the most likely cause is overvoltage (which I tend to believe, I was indeed running it up to 470V without a battery, after all).
DC bus is shorted as are 4 of the IGBTs (all other components on the heatsinks seem fine), so I ordered another identical model inverter from the seller for good measure, + a whole set of new IGBTs and MOSFETs/diode/DC fuse to try and repair the old one.
Now, the seller is telling me that also a lower end voltage below 360V (MPPT runs from 120 to 450V) can damage the transistors IF used without a battery, because the inverter will suffer from voltage instability. I have since then rewired my panels to be 2 x 5 instead of 1 x 10, which makes them 225-240V per string, and I cannot happily add more panels to the strings as I am at 4450W already, with a 6000W limit for the inverter, so could go to 280V per string, but no more.
So, is the above information about selecting optimal voltage solid, and is there any other advice to avoid premature death of an inverter? (except for the usual "keep it away from dust and humidity")
If I really wanted to add more panels to the strings, so they are around 360-400V each, would a safer setup be having two inverters, each one connected to one solar string, and both connected in parallel to the same battery(es), with just one of them supplying AC to the apartment?
Would connecting two separate inverters in parallel both to the battery and the panels make sense at all? No, right? As if one suddenly died, the other would start getting blasted by the whole power of the array, and die in the wake of the first.
Addendum: seller just told me something that doesn't make much sense to me, that is, connecting two inverters to the same battery, even if they are connected to separate solar strings, and only one of them actually provides AC to the house, is possible but will need a large capacity battery or I risk damaging both inverters.
I was careless, to say the least, in connecting it with 10x 445W longi panels in series, totalling 480V on open circuit ("heh, the inverter holds up to 500V open circuit, what can go wrong") failing to see how the max MPPT voltage was actually 450V.
Going by the wifi datalogger it reached 470V multiple times during production (only 2 short days of life while actually being loaded, probably went a week with no load at all and just connected to panels before I managed to rewire the apartment), after installation I had it running without battery (was still balancing my EVEs) until one afternoon it just died, error 09; after consulting with the AliExpress vendor (who is always patiently responding to my many questions) the most likely cause is overvoltage (which I tend to believe, I was indeed running it up to 470V without a battery, after all).
DC bus is shorted as are 4 of the IGBTs (all other components on the heatsinks seem fine), so I ordered another identical model inverter from the seller for good measure, + a whole set of new IGBTs and MOSFETs/diode/DC fuse to try and repair the old one.
Now, the seller is telling me that also a lower end voltage below 360V (MPPT runs from 120 to 450V) can damage the transistors IF used without a battery, because the inverter will suffer from voltage instability. I have since then rewired my panels to be 2 x 5 instead of 1 x 10, which makes them 225-240V per string, and I cannot happily add more panels to the strings as I am at 4450W already, with a 6000W limit for the inverter, so could go to 280V per string, but no more.
So, is the above information about selecting optimal voltage solid, and is there any other advice to avoid premature death of an inverter? (except for the usual "keep it away from dust and humidity")
If I really wanted to add more panels to the strings, so they are around 360-400V each, would a safer setup be having two inverters, each one connected to one solar string, and both connected in parallel to the same battery(es), with just one of them supplying AC to the apartment?
Would connecting two separate inverters in parallel both to the battery and the panels make sense at all? No, right? As if one suddenly died, the other would start getting blasted by the whole power of the array, and die in the wake of the first.
Addendum: seller just told me something that doesn't make much sense to me, that is, connecting two inverters to the same battery, even if they are connected to separate solar strings, and only one of them actually provides AC to the house, is possible but will need a large capacity battery or I risk damaging both inverters.
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