Thread: Solar panel Amps

Originally Posted by Pedro_The_Swift

My god Weeds,, thats the longest post you've ever made

and it took hours of typing.........

Originally Posted by Blknight.aus

1. full short amps. this is how much the panel will try to pump out if you just short the output, all your wiring needs to be able to handle this if you dont have fusing or circuit breakers at the panel. its aslo the maximum amps that can be pushed through the panel if you have a string of panels
.

You don't use overcurrent protection on the panels, they are current limiting and with any protection it would either be to big to operate or too small and operate in good conditions

eg. ISC of 5A, maximum current ouput of the panel, so when it shorts out, it has 5A current flow in ideal conditions, so what overcurrent protection do you plan on fitting? 4A so it blows all the time or 6A where its completely useless as its impossible to achieve that current draw?........just wondering?



Pedro, just buy what ever is cheap and fits within the voltage regs limits

read again
your wiring must be able to handle these amps IF you dont have fuses or circuit breakers,

Ergo IF your wiring can deal with what the panel can pump out THEN you dont need fuses/CB.

however

I generally use the nominal flat battery voltage to work out the amp rating of a fuse for a solar panel for a 12V system I use 10V just because its easy and most fuses have a fairly generous margin unless you're fitting exotic fuses (auto fuses are about as slow as you can easily buy) and then for a cricuit breaker I use the nominal amps at the correct charging voltage for the battery (so perfect world a 10a breaker on a 138W panel to charge 12V batteries)


on an 80W panel I fit a 10A fuse and on a permamant fixture intended to be left unattended an 8A self resetting circuit breaker.

some panels have a blocking diode built in and others have the regulator as part of the panel. If you're using the blocking diode you dont need the fuse as the diode will burn out doing the same job and the jobbies with an inbuild regulator deal with the problem via the regulator.

Originally Posted by weeds

have you considered the 2 panels folded up and tranported in a carry bag, this allows the van to be in the shade, just face the panel to the north at 30-40 degrees off the deck, sit back and enjoy your beers.

For the fold up panel thing, I just have two normal 59w panels and screwed two hinges to them. This folds the glass fronts onto each other.
Then I double sided taped a Morning Star regulator to the back of one and added long twin cable with the usual small andersen connector on it. Even then I had to make an extension lead.
You will get lots more power back into your batteries if you can move your panels around to avoid shade and follow the sun.

Only down side is they are bulky to pack like this.

Just make sure you're comparing apples to apples. In my experience the larger panels are generally 24vDC and the smaller 12vDC. Once you get to around 130W panels and above then some are still 12vDC but most are generally 24vDC.

As for a regulator I'm using a Plantronics 40amp and that works fine.

Mike

Originally Posted by Blknight.aus

read again
your wiring must be able to handle these amps IF you dont have fuses or circuit breakers,

Ergo IF your wiring can deal with what the panel can pump out THEN you dont need fuses/CB.

however

I generally use the nominal flat battery voltage to work out the amp rating of a fuse for a solar panel for a 12V system I use 10V just because its easy and most fuses have a fairly generous margin unless you're fitting exotic fuses (auto fuses are about as slow as you can easily buy) and then for a cricuit breaker I use the nominal amps at the correct charging voltage for the battery (so perfect world a 10a breaker on a 138W panel to charge 12V batteries)


on an 80W panel I fit a 10A fuse and on a permamant fixture intended to be left unattended an 8A self resetting circuit breaker.

some panels have a blocking diode built in and others have the regulator as part of the panel. If you're using the blocking diode you dont need the fuse as the diode will burn out doing the same job and the jobbies with an inbuild regulator deal with the problem via the regulator.

No need too, the panel has an ISC rating which it won't exceed, current limiting, no need for any protection on the feed from the panel to the regulator, it will either be a nuisance or never work...ever. after the reg on the other hand is different as it will be fed ffrom the battery, capable of lots of amerageres

after having seen the wires from an array merrily melting away I'll fit fuses..

If it only burns your vehicle down once a year, its a bad year.

Originally Posted by Blknight.aus

after having seen the wires from an array merrily melting away I'll fit fuses..

If it only burns your vehicle down once a year, its a bad year.

Correct, they will melt away merrily, but aside from trying to take it to an extreme^^^^, the facts remain, you either fuse it below its rated ISC and it will blow/trip the overcurrent protection or fuse it over the ISC rating and if there is a fault it will continue to merrily melt away

So, either your fitting overcurrent protection on the array side, that will nuisance trip or wont function at all