Santiago
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Solar panel wiring diagram
Continuing Doug's solar threads, I intend to wire my stuff together on 3/4" plywood following this wiring diagram. Anyone see anything wrong with this or differently they would do?
Thanks
edit: my only difference is that I will have different makes of chargers/inverters and I will not wire in 220v at this time. I'm talking a small
600-800watt system. my inverter will only be a 1500.
[Edited on 8-19-2010 by Santiago]
[Edited on 8-19-2010 by Santiago]
[Edited on 8-19-2010 by Santiago]
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Bob and Susan
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if you are using a better controler that can convert higher voltage to 24v
bring the current from the panels down at 72v
your combiner box needs to support this
the controler then draws it in at 72 volts
and distributes it at 24 volts
this will elliminate heat problems in the summer
and you can use smaller wire
or
use #2 cable from the solar panels to the controller at 24v
heat in the summer is you enemy
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monoloco
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The size cable between the array and charge controller is determined by the amperes of the array and the distance to the controller. Refer to a wire
sizing chart for the correct wire gauge for your application.
[Edited on 8-20-2010 by monoloco]
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Bob and Susan
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| Quote: | Originally posted by monoloco
The size cable between the array and charge controller is determined by the amperes of the array and the distance to the controller. Refer to a wire
sizing chart for the correct wire gauge for your application.
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no...this is BAD advice THIS time
people size for temps in the usa not baja
its way hotter down here
thus... more resistance in the wire when its hot
lots of problems here in the summer with people that used this system
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monoloco
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You are correct about temperature and compensating with larger wire, but if someone was running a couple of 75 watt panels and they were only 10 or
15' from the controller there would be no need for #2 wire, conversely if they had 3kw of panels, and they were 100' from the controller #2 wire would
be grossly undersized. You just can't make a blanket statement regarding wire sizes.
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Santiago
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I understand the issue of distance, voltage etc. I think at most I am about 12' of run from the nearest corner of the PV array and the combiner box
and I will oversize one wire size. I will probably have three 205 panels so I think I must run them to the combiner box at 12v. Big wire, si?
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monoloco
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It depends on what type of controller you use. If you use an mppt type controller you can wire the panels in series and will not need as large of wire
as you would need if the panels were wired in parallel at a lower voltage. Higher voltage= lower amps= smaller wire. It is just like when you are
running a tool at 220v vs.120v, there are half the amps at 220v so you can run smaller wire.
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Pompano
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I found this very informative..maybe it will help in your decisions with the wiring.
Good luck and have fun with solar power like the rest of us Baja nuts.
http://www.freesunpower.com/wire_calc.php
I do what the voices in my tackle box tell me.
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Bob and Susan
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i disagree with them...
but i'm only a old guy with no professional training
now...lots of resistance in a 12v system
plan for the future and build the wiring for that
big stranded wire is better
200w is the match for ONE 6 volt battery
you need 400w for two
an mppt controler will not work well on a small system
it "sleeps" until it receives 200w
remember the sun is only "full-charging" about 5 hours a day
nighttime use is maybe 6 hours
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Doug/Vamonos
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Damn Santiago! I got dizzy just looking at that schematic. The cervezas probably did not help. What are you planning to build there? Maybe you can
sell some power to me?
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BigWooo
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Santiago,
Do you plan to use an E-Panel (where the drawing came from), or buy and build the breaker boxes, etc. yourself? I did the math and added up the cost
of buying all the components myself, or just purchasing an E-panel. It was only slightly more to buy the pre-assembled E-panel. The cost was close
enough that it wasn't worth the headache of building it myself.
You may be more talented than I am, but I definitely couldn't come up with a cleaner package than they offer by doing it myself.
Midnight Solar E-Panel
Edit: add link
[Edited on 8-21-2010 by BigWooo]
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monoloco
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I did the same thing, and I'm glad I did. The E-panel rocks.
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BajaGringo
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| Quote: | Originally posted by Bob and Susan
i disagree with them...
but i'm only a old guy with no professional training
now...lots of resistance in a 12v system
plan for the future and build the wiring for that
big stranded wire is better
200w is the match for ONE 6 volt battery
you need 400w for two
an mppt controler will not work well on a small system
it "sleeps" until it receives 200w
remember the sun is only "full-charging" about 5 hours a day
nighttime use is maybe 6 hours |
I agree with Bob on the wiring. We are in San Quintin, farther north and lower summer temps but we still see a loss on the warmer days. At least 10%
on our parallel wired panels feeding our 24 volt system. I will be rewiring my panels coming down to series-parallel this coming week to double the
voltage.
Bob - what kind of mppt controller do you use that it doesn't wake up until 200w? I have a pair of Xantrex XWMPPT60 controllers and I routinely see
them start pumping out amps at less than 30 watts on early mornings.
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monoloco
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The loss you are seeing could also be due to the fact that solar panels lose efficiency at higher temps.
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Santiago
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I waffled on the DYI or buy-the-E-panel but since I'm a little bit stupid on this stuff I figure I will be forced to learn how this all works. Most
of the 'experts' I've talked to seem to think I should stay away from the MPPT with such a small system (500-600 watt PV).
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BajaGringo
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| Quote: | Originally posted by monoloco
The loss you are seeing could also be due to the fact that solar panels lose efficiency at higher temps. |
True and the loss is enough that it makes it very difficult to equalize my batteries in summer. Another good reason to go with the higher voltage.
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monoloco
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I'm sold on the MPPT controllers and higher voltages, it's a much more efficient way to go.
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Bob and Susan
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| Quote: | Originally posted by monoloco
I'm sold on the MPPT controllers and higher voltages, it's a much more efficient way to go. |
us too...
we have outback mx60 controllers
one died in the hurricane last year
so i'm using a back up junky trace for one inverter
(remember: here in baja ALWAYS have a "backup plan")
i'm looking for a replacement but want the "correct price"
they are easy to read, program and equalize the batteries
the new replacement mx80's are better
i agree...you should send down 72 volts from the panels and use as 12-24-48-72 volts at the inverter
the controller takes care of this
some of my "palapa neighbors" had trouble with their outbacks "sleeping" because they didn't have enough wattage from their panels
maybe you can change the setting for "sleep"...i don't know
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