So I took every EPEver/Victron/PWM/Renogy solar charge controller, and tried to fry it by connecting it only to solar panels, and not to a battery... guess which one survived?
EVERY SINGLE ONE! I couldn't destroy any of them, and I left them connected to a high voltage array (80 volts) for 4+ hours each.
I connected each one to a lifepo4 bank after the test, and they functioned perfectly. Tested output with a watt meter before and after as well, no change.
I read in the manuals that you must NEVER connect an SCC to an array without connecting it to a battery first, because the potential that it can fry. I know that having improper gauge wires on an SCC can cause overheating around the terminals (dedicated voltage sensing leads would probably fix this problem, but many SCC use the charging lines as voltage sensing, which makes it wise to over gauge them most times. The voltage drop of a long run of hot wire can be horrible). But to actually connect an array to an SCC, and not to a battery, in my experiments, no issue.
I am thinking that the feedback signal in the converter circuit needs a reference voltage at the output to work. Then it can track the power point between the panels resistance and internal resistance of the battery, then push current to the max. If you only have the input powered up but no current is flowing, what would it stress? The panel would be in an open circuit voltage, and possibly use some power to charge up caps on that side of the circuit, but thats about it. Should be fine to leave connected.
Am I wrong? I know some MPPT's circuit designs are pretty complex, but they are still a simple converter circuit with inductor and capacitor and basic logic system to modulate it. I know some current limited converters can handle amp sources at input/output, and others can't. but because the solar panel is open circuit in this instance, and the output is also voltage sensing of the battery, I don't think any damage can occur.
What do you guys think? How can I destroy one?
EVERY SINGLE ONE! I couldn't destroy any of them, and I left them connected to a high voltage array (80 volts) for 4+ hours each.
I connected each one to a lifepo4 bank after the test, and they functioned perfectly. Tested output with a watt meter before and after as well, no change.
I read in the manuals that you must NEVER connect an SCC to an array without connecting it to a battery first, because the potential that it can fry. I know that having improper gauge wires on an SCC can cause overheating around the terminals (dedicated voltage sensing leads would probably fix this problem, but many SCC use the charging lines as voltage sensing, which makes it wise to over gauge them most times. The voltage drop of a long run of hot wire can be horrible). But to actually connect an array to an SCC, and not to a battery, in my experiments, no issue.
I am thinking that the feedback signal in the converter circuit needs a reference voltage at the output to work. Then it can track the power point between the panels resistance and internal resistance of the battery, then push current to the max. If you only have the input powered up but no current is flowing, what would it stress? The panel would be in an open circuit voltage, and possibly use some power to charge up caps on that side of the circuit, but thats about it. Should be fine to leave connected.
Am I wrong? I know some MPPT's circuit designs are pretty complex, but they are still a simple converter circuit with inductor and capacitor and basic logic system to modulate it. I know some current limited converters can handle amp sources at input/output, and others can't. but because the solar panel is open circuit in this instance, and the output is also voltage sensing of the battery, I don't think any damage can occur.
What do you guys think? How can I destroy one?
