used solar panels

[doublegregg]

a recycling place near me has used solar panels...  he said 190w for $76, 120w for $48... he said 37v. that sounds appropriate for my controller - that is, for my epever controller, which can take 12 or 24 v dc. does this all sound good for potential vehicle use? what should i look for other than just testing open circuit voltage? i believe they will take them back if they don't work... and when i last looked at these panels - the ones i looked at were pretty big and heavy.i'm just guessing......... 5' tall? um... heavy, for me.......i'm guessing... 50 pounds?

do i want poly or mono????  and i guess these would be good for home use, except for the low voltage... altho - i'm just learning this stuff... so i guess you could connect them serially to increase the voltage, and then they'd be good for the home?

ty!

 

[jimindenver]

The fact that your charge controller can do 12 or 24 volts has nothing to do with the solar panels. It means that it can be used on a 12 or 24 volt battery bank. You need to make sure that you have a MPPT controller to take advantage of higher voltage panels.

Personally I prefer the output of poly panels in overcast situations unless you are talking about a high efficiency panel like those from SunPower.

I only design Off grid and RV solar. On grid is a much more complicated matter.

 

[jonyjoe303]

As long as the panel fits on your roof use it. I have a 240 watt panel on my astrovan and I would get a bigger one if i could get it to fit without going over the edges. 37 volts is about normal for the large panels, thats what I get on my panel. The smaller panels like 120 watts are in the 21 volt area. Your epever is probably mppt and will work with most panels, there is usually a max voltage not to exceed, my mppt controller maxes out at 45 volts some go as high as 150 volts.

I would get the biggest panel that would fit on your roof, for me 190 watts would be too small (maybe 9 amps charge power), with the 240 watts I get an average of 12 amps, I wouldnt want to go lower then that. I wouldnt even consider getting a 120 watt panel (about 6 amps).

 

[doublegregg]

thanks jim. it is an mppt controller, an epever. if i use the panels at my house, they won't be tied in to the grid. i no i don't no how to do that.

and thanks jonyjoe, i'll lean to the 190w or more.... i'm kind of trying to be a little stealth, so don't relish a huge panel up there... i'm thinking of occasionally removing it as needed. also, i have not figured out about putting that hole in the van for it.......... that'll come later, as i can only absorb so much.... i also have 300w in a dokio portable unit...

so - anyone else - does this sound like a good deal, assuming the panels work? it seems good to me, and i'm thinking of getting one........ as i said, i'm new to this solar stuff, and jumping in. and i wanted to be able to use this on either my home or vehicle...

 

[Trebor English]

Check the solar charge controller spec for maximum input voltage.  Often it will kill the controller if you give it more volts than it can take. 

Most general purpose multi meters are suitable for measuring the 40 volts open circuit voltage.  If it is a 200 watt 72 cell "24 volt" panel the short circuit current (Isc rating on the sticker) will be about 7 or 8 amps.  Most multi meters can measure that too.  If the panel voltage open circuit is good and the short circuit current is good it is probably a good panel.  If the rating is 7 amps and the panel is not aimed right at the sun expect substantially less than 7 amps. 

If you try to measure current and use the wrong meter scale you can pop a fuse in the meter or fry the meter.  Most cheap meters come with test leads that will be challenged by a current that high.  If you have no experience with measuring current you might want to skip this test.

For the same wattage poly panels are a bit bigger and a bit cheaper than mono.  Since your price is a whole lot lower than $1 per watt you won't be going wrong. 

I have a 100 watt panel on the roof of my mini-van with no hole in the roof.

 

[doublegregg]

thanks for the reply, trebor, and instructions. i could do a current test... not used to that, but can.

how did you put the panel on the roof with no hole? i am, liek most i guess, not happy to think of putting a hole in my roof. i watch marine videos on solar --------- the guy there advocated holes in vertical surfaces... no possible pooling of water. a boat probably has a wider variety of surfaces than a vehicle.

i just was wondering if the say $67 for a 167w sharp mono panel was a bargain, or pretty much going rate for used panels... it's a nd 167u3a, listed as residential... i'd want it for either my van or to try at home. no, not tying into the power grid.

my epever 40a controller has a max pv open circuit V of 150v --- so i'm assuming however the panels are wired up ---- that's the maximum V my controller will take?

bob mentioned santan solar, in his live feed recently. i'd consider going there, or elsewhere, but it's a two day drive from the bay area...

 

[Trebor English]

My Ford Windstar came with a roof rack.  My panel is bolted to that using holes drilled in the cross bars.  The wires pass through the left rear door and down the B pillar that separates the left front door from the left rear door.  It's vertical so there's no water pooling.  The foam rubber door gasket formed to match the bump where the wires pass through.  The wires are held in place by zip ties at the roof rack and inside through a couple of holes in the plastic panel over the B pillar.  That door gets opened very rarely.

 

[highdesertranger]

got one of my current 435 watt panels from SanTan solar. from Southern California it was still a 2 day run. was it worth it? hell yes. I got another of the same panels from JiminDenver for a total of 870 watts, thanks Jim. luckily I could pick them both up on the same trip. highdesertranger

 

[doublegregg]

thanks hdr, i'll check otu santan.... sounds like they have great prices. you can fit 870 watts on your roof?

trebor, i'd like to avoid putting holes in too.... i'll maybe try to sneak in one of the doors... idk, maybe i'll hook up my roof panel as required.... i have my dokio...

g

 

[highdesertranger]

yes and I have room for more,




highdesertranger