I have decided to place an additional layer of protection between my Ecoflow Powerkit and my solar panel array. To ensure that no more than 150v/15a(breaker rating) get to my powerhub I am going to put the breaker next to the powerhub between it and my solar disconnect switch. I am very new to this type of wiring. The breaker only has a positive set of terminals, and I understand that the breaker is polarity sensitive....am I correct that I only need one breaker for the positive line and that the negative line needs no breaker?
DC breaker question
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In short it won’t work. Your controller will not take more amps that it is rated for and so the breaker won’t trip unless you undersized it for less than your unit can handle also the breaker won’t trip for voltage and so you get no protection that way either. It is a good Idea to have a switch to turn off the array so that you don’t damage the connections from arcing when unplugged live but that should be an oversized double pole breaker or switch rated over the max VOC of your array. It needs to be double pole to avoid back feeding.
I don't understand this. I've only used single pole on the positive to disconnect the array from the charge controller for "maintenance". on the charge controller. I've also seen others only use single pole. Why the double pole?
The goal of installing the circuit breaker is to avoid my solar array from being able to feed more than 150v/15a to my powerhub as a safety. I already know if you feed more power to the Ecoflow Powerhub than it is rated for (it can be damaged like any MPPT I've seen on many videos). My question is simply do I need two breakers, one for negative and one for positive or just one for the positive solar panel feed?
John Frum
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Please explain.
My point was that the breaker will not trip for high voltage. The only thing a breaker does is limit amperage. Since breakers do not trip immediately upon receiving higher than their rated amperage even the breaker limiting amperage will not work to protect your MPPT controller. As far as whether it should be double pole or single pole for turning off the array in regards to cutting power a single pole will work. However double pole breakers or switches are recommended because if a solar panel malfunctions it is possible to have live power backfeeding through grounded metal surfaces. It’s a safety thing.
First of all if the charge controller is attempting to put a load on the panels there will be power between one side of the breaker and the other side of the breaker and you can get shocked there that’s an unlikely scenario since most controllers simply turn off when they don’t sense voltage. The more likely scenario is that you have a wire from a solar panel shorted out against a metal surface or a malfunctioning solar panel this can make voltage between any grounded surface and the incoming line that is not switched. although unlikely these scenarios are extremely dangerous because they will be totally unexpected. Very easy to prevent with very little additional money.
I do want to clarify that I am making these statements in regards to the 150 V charge controller at the beginning of this thread. If your solar array is has a VOC of less than 48 V a single breaker is probably fine it’s the shock hazard is extremely low under those circumstances.
John Frum
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Do both of these scenarios assume an isolation fault in the solar charge controller?
UPDATE: Question mooted by near simultaneous response.
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John Frum
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@Bobert have I correctly summed your scenarios?
Especially with less than 3 strings which are commonly un-fused and since panels are current limited and therefore unlikely to clear a short or ground fault, the double pole switch provides extra protection.
Which is increasingly important as the string voltages increase.
I think I see GFCI for pv circuits coming down the pike.
Especially with less than 3 strings which are commonly un-fused and since panels are current limited and therefore unlikely to clear a short or ground fault, the double pole switch provides extra protection.
Which is increasingly important as the string voltages increase.
I think I see GFCI for pv circuits coming down the pike.
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Thanks for the responses. I am right at the limit on my solar panels generating the 150v and 15amps. Given that I think it's technically possible(IE cold day and perfect solar angle) to exceed the rating, I'm putting in extra safety into my build. If it never trips, then fine and I'll still be happy.
Just as long as you realize that a circuit breaker will not trip for over voltage. Slightly over amperage is common practice and really seldom a problem except for the 500v + controllers. Over voltage is different it can happen and usually does happen with no load on the controller. I know of no way to protect against that other than the proper panel configuration.
