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An Approaching RF Shinola Storm?




 
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KD6VXI
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« Reply #25 on: June 19, 2018, 07:25:21 PM »

They make tape heaters.  Copper foil with a small current through them.

Same principal as what they use on the small pizza box size dss dishes, although they don't cover the entire panel.  Just a small thin strip along the lowest point, to keep anything from. Building up on the lip.

RainX works to prevent buildup as well, although I've never tested it to see if it also lowers the sunlight.

This is a real problem.  There are fixes.





The disconnects should all be rated at 480 or 600 vdc.  On the DC side.  On AC side, they are rated for split phase 240 although most buy in bulk and companies that do commercial will usually buy ones rated at 480 for everything.  Less inventory.

--Shane
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WA2SQQ
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« Reply #26 on: June 20, 2018, 09:39:32 AM »

So while my son was a firefighter here in NJ I recall him telling me that if there's a house fire, and solar panels on the roof, "we aren't going up on the roof". The local Target had a fire. Solar panels on the roof, so the local power company had to come down and disarm them before the FD would go up on the roof.
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KD6VXI
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« Reply #27 on: June 20, 2018, 11:45:00 AM »

We are now required to install what is called RSD or Rapid ShutDown.  It kills all output to 1 volt per panel.

I can't blame him, 4 to 500 volts DC is nothing to sneeze at.


--Shane
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K6JEK
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« Reply #28 on: June 27, 2018, 04:05:28 PM »

We are now required to install what is called RSD or Rapid ShutDown.  It kills all output to 1 volt per panel.

I can't blame him, 4 to 500 volts DC is nothing to sneeze at.

--Shane
KD6VXI
Shane, what does this amount to for existing string inverters? I'd guess a remote disconnect up near the panels that somehow works in tandem with the existing DC disconnect near the inverters. Did I guess right?
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KD6VXI
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« Reply #29 on: June 27, 2018, 10:37:15 PM »

Existing systems will not be required to retrofit.  Stupid.

If it's an optimized string system usually a simple firmware update gives each optimizer the capability to RSD at 1 volt. 

If it's a simple string system, their are a couple RSD boxes available.  Some integrate with an inverter that has a 120 v relay in it.  The RSD box will drop the string voltage to a regulated 24 volts and you run a 2 conductor cable to either the inverter or a pushbutton shutdown (panic button style).  That button just interrupts the 24 volt signal looped.

In a dumb string system with an inverter capable of interfacing with an RSD all they have is a relay that shorts upon successful self test on the inverter.

In any case, the RSD is supposed to be wired to where if the main disconnect to the house has been shutdown (main breaker), you can ONLY have 48 volts ANYWHERE on the roof.

If you Google Fronius RSD, those have pretty good instructions.  Their RSD box is also a combiner so you can combine several strings rooftop before running lots of wire back to the inverter.  A single twin run of 8 is usually cheaper than 4 runs of 12.  I use the combines to also split a roof.  You can combine strings on the east and west side of a house.  As the sun moves, one string comes down in current, the other increases.  They have steering diodes to keep you from backfeeding, and the mppt controllers in the inverter keep the AC power constant.

Win win for Johnnie and Jamie homeowner!

--Shane
KD6VXI
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