MarcMassanari
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Is it recommended to have a disconnect switch, fuse or breaker between the solar panels and the MPPT?
PV Panel Disconnect
- Thread starter MarcMassanari
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timselectric
If I can do it, you can do it.
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Yes
If only 1 or 2 strings, you can just have disconnect.
If 3 or more strings, each string needs to be fused.
Either way, a maintenance disconnect is suggested.
If only 1 or 2 strings, you can just have disconnect.
If 3 or more strings, each string needs to be fused.
Either way, a maintenance disconnect is suggested.
littleharbor2
Solar Addict
If you have 3 or more strings of panels you need to have fusing/circuit protection on each string.
Regardless of the number of strings it is a good thing to have a 2 circuit box with DC rated breakers between the PV array and CC AND between CC and battery bank. This is a good way to shut down for maintenance battery switching etc.
Regardless of the number of strings it is a good thing to have a 2 circuit box with DC rated breakers between the PV array and CC AND between CC and battery bank. This is a good way to shut down for maintenance battery switching etc.
littleharbor2
Solar Addict
You always want to shut down PV first before shuting down the battery connection. When rebooting the CC you always want to reconnect the batteries first to let the CC boot up, then turn on the PV.
pellicle
retired ex-professional dingbat
I agree with all the answers, but my question is "why wouldn't you"
I put in a 20A DC circuit breaker which can also be manually tripped (this one) on each of my DC circuits (panel to SCC, SCC to battery). I'm in Australia so I bought that one, but you must be able to find something similar.
No. The less stuff to go wrong the better!
Bad disconnect switches have burned down a lot of houses here in Australia and there really is no need for a fuse.
WYtreasure
It's not happy hour, I'm just like this.
YES
A combiner box with circuit breakers is one way to accomplish the task (without it becoming a fire of known origin). Another product, a safety switch, can safely disconnect a loaded circuit thousands of times without fail. I use both, combiner at the array and safety switch next to the charge controller. I like my house.
Some folks use the wrong type of switch/disconnect and fail to remove the load from the circuit. Some disconnects are designed to be used under load, some are not. A loaded DC current causes a spark when the circuit is broken. There are many stories, with pictures, of switches failing as a result of the spark which occurs when disconnecting loaded DC circuits with the wrong product.
Things to consider when installing and using a disconnect are the current and the frequency of use. Another consideration would be a structure or vehicle fire caused by a $15 piece of ...
A combiner box with circuit breakers is one way to accomplish the task (without it becoming a fire of known origin). Another product, a safety switch, can safely disconnect a loaded circuit thousands of times without fail. I use both, combiner at the array and safety switch next to the charge controller. I like my house.
Some folks use the wrong type of switch/disconnect and fail to remove the load from the circuit. Some disconnects are designed to be used under load, some are not. A loaded DC current causes a spark when the circuit is broken. There are many stories, with pictures, of switches failing as a result of the spark which occurs when disconnecting loaded DC circuits with the wrong product.
Things to consider when installing and using a disconnect are the current and the frequency of use. Another consideration would be a structure or vehicle fire caused by a $15 piece of ...
MarcMassanari
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Thanks for all of the replies. I have 4 100w panels connected in series/parallel.
@pellicle , those circuit breakers look very similar to one that a forum member posted about last year. It was causing havoc in his system. Those breakers may be good for car audio but I would never use them in a PV/LiFePO4 system.
Zwy
Emperor Of Solar
If 3 strings or more are in parallel. Only needs a disconnect if each string is treated separate. An example, the LV6548 has 2 PV inputs per unit. If there are 2 LV6548's in parallel configuration and there are 4 strings each separate with each string running to one PV input, only a disconnect for each string would be required.
If 2 strings are put in parallel at the PV array and then split into 2 at the SCC with 2 PV inputs, it would not require a fused disconnect.
I agree.
timselectric
If I can do it, you can do it.
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timselectric
If I can do it, you can do it.
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Zwy
Emperor Of Solar
kromc5 has been doing it for some time.........
timselectric
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Zwy
Emperor Of Solar
https://diysolarforum.com/threads/v...l-specs-of-the-whole-system.11532/post-396563 Start there, works just fine.
timselectric
If I can do it, you can do it.
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I would never recommend doing that. If, something happens to one mppt, the other will be way overloaded. Which could leave you with nothing.
Just because it seems like it will work, doesn't make it right or safe. But as I said, it's a free world.
Just because it seems like it will work, doesn't make it right or safe. But as I said, it's a free world.
littleharbor2
Solar Addict
How does a MPPT SCC find the maximum power point on 1/2 of a circuit?. How for that matter does it know to take only half of it?. It just plain doesn't make sense. Each SCC needs it's own dedicated array.
timselectric
If I can do it, you can do it.
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I'm guessing that one wins the battle, and the other gets whatever is left.
