small solar system help

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TheArmsman
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Re: small solar system help

Post by TheArmsman » Mon Aug 14, 2017 5:19 pm

Vonz90 wrote:My thoughts on PV (Keep in mind that I am an engineer on the NPV side, not a consulting engineer. However, we make a lot of components that go into PV systems, etc - mostly on the utility level rather than residential, but some of that too.) I do occasionally go vote on the NFPA stuff related to it too.

1. I am mostly not a fan, but it has it niches.
2. I would never put solar panels on any permanently occupied structure (like my house).
3. Putting it on remote or out buildings is probably okay (so your friend's application is potentially okay in my book).
4. Don't go too cheap, some of the crap from China and whatnot is dangerous IMHO.
5. Make sure you put an emergency disconnect that is well marked and accessible or the fire department will let your structure burn to the ground if the see solar panels on it (they may anyway, but at least you have a shot at them doing something.)
2. Regarding this question, why would you not put solar panels on a permanently occupied structure? Are they a fire or electrical hazard?
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Vonz90
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Re: small solar system help

Post by Vonz90 » Mon Aug 14, 2017 8:32 pm

TheArmsman wrote:
Vonz90 wrote:My thoughts on PV (Keep in mind that I am an engineer on the NPV side, not a consulting engineer. However, we make a lot of components that go into PV systems, etc - mostly on the utility level rather than residential, but some of that too.) I do occasionally go vote on the NFPA stuff related to it too.

1. I am mostly not a fan, but it has it niches.
2. I would never put solar panels on any permanently occupied structure (like my house).
3. Putting it on remote or out buildings is probably okay (so your friend's application is potentially okay in my book).
4. Don't go too cheap, some of the crap from China and whatnot is dangerous IMHO.
5. Make sure you put an emergency disconnect that is well marked and accessible or the fire department will let your structure burn to the ground if the see solar panels on it (they may anyway, but at least you have a shot at them doing something.)
2. Regarding this question, why would you not put solar panels on a permanently occupied structure? Are they a fire or electrical hazard?
They are only nominally more of fire hazard than any number of other things. However, unlike most other things there is no way to "turn them off" if something bad happens. The bad thing that happens does not have to be caused by the PV for the presence of the PV to cause a problem.

Most fire men/departments are not real into being electrocuted to death when spraying water onto a fire. By code most everywhere, there is an outside disconnect on your home/business they can open and be safe to spray down the building. If you have PV cells on your roof, they will likely stand back and let it burn because they have no way of knowing that they will not spray something energized.

The emergency disconnects are supposed to cut the power withing XX ft of the solar array (I do not remember off hand and do not feel like looking it up but say 5 feet or something like that). So they can spray without worry. Of course they still may be worried that it is installed right. If they think you have a "Wall of power" battery system or something like that in your house they may still not do it even if it is night time.

The disconnects are going into the NEC in 2018 (already approved and such) but they will not filter down to all of the local codes until somewhere between years and never. Still a good idea if you are installing a system even if code does not require it. (... and the company I work for does not make said disconnects so I am not trying to sell anything.)

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Termite
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Re: small solar system help

Post by Termite » Mon Aug 14, 2017 9:09 pm

If he stays with a 12 or 24 volt DC only system, electrocution isn't really a hazard. 24VDC systems have an open circuit voltage of about 40VDC, 12vdc systems are half that.

If he goes with high voltage DC to AC grid inter-tie using a phase matching inverter, then yeah.
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Vonz90
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Re: small solar system help

Post by Vonz90 » Tue Aug 15, 2017 1:30 am

Termite wrote:If he stays with a 12 or 24 volt DC only system, electrocution isn't really a hazard. 24VDC systems have an open circuit voltage of about 40VDC, 12vdc systems are half that.

If he goes with high voltage DC to AC grid inter-tie using a phase matching inverter, then yeah.
Sure, it would be safe but it doesn't really matter. It depends on the perception of the guy on the scene. Some PV systems go up to 1500 Vdc. Not many residential rooftop systems go up above 48 Vdc or so, but some go up over high enough enough to be a potential danger, and if they are pared to a 120 or 240 volt inverter then you still have 120 or 240 Vac somewhere. If the firefighters show up and say they do not want want to risk it, then the house goes down.

Maybe low risk in the big pictures scheme of things, but I am risk averse to that sort of things, especially considering the marginal benefits to a PV system.

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