I'm looking to add 10 solar panels They will be about 250 feet from the controller. The panels are 28.90 Vmp, 36.1 Voc. Do I go by the Vmp or the Voc? I want to put 5 together to get the wire size down. I live in Maine. 150 or the 200?
Thanks Brian
Brian
You would use the VOC so 36.1 multiplied by 5 would give you a non temp corrected VOC of 180.5 with a 1.2 multiplier you would be around 216VOC this would keep the Classic 200 from waking up on those cold mornings. I would go with a 250 or a different configuration on the panel layout. I forget what battery voltage you are running now but seem to remember 48? Also what wattage are the 10 panels?
Ryan (In Maine as well)
Hi Ryan. Remember me I came up to see your wind turbine two years ago.
The panels are 220 watts. And my batteries are at 24 volts. Would I be better off just tiring just 2 panels together?
Thanks Brian
Power (W) 220 Watts
Open Circuit Voltage (V) 36.10 Voc
Short Circuit Current (A) 8.21 Isc
Maximum Power Voltage (V) 28.90 Vmp
Maximum Power Current (A) 7.62 Imp
These are the specs of the panels I haven't bought any yet, just planning.
Brian
Brian
At those specs and distances a 250 would work with 2 strings of 5. A Classic 150 with 2 in series would be the best charge controller wise but that will mean heavier wire.
With 5 strings of 2 panels going to a Classic 150 I show 2/0 cable with a 2.59% Voltage Drop
With 2 strings of 5 going to a Classic 250 I show #6 with a 2.01% Voltage Drop and #8 with a 3.19% Voltage Drop
We typically shoot for 2% or less on the voltage drop so you can see there is a difference in wire size so the question is do we pay for the wire or pay for the extras to run high voltage? You will need a 300 volt combiner with 2 300 volt breakers this will cost about the same as a 150 volt 5 position combiner. and you will need a 300 volt breaker at the input of the Classic so the cost difference is not a lot.
Ryan
So the out put amps would be ok on the 250?
Brian
You did say 10 panels total if I am reading correctly so 2200 watts on a 48 volt battery is just fine the 250 is good for 300 to 3200 watts.
Thanks but my batteries are at 24 volts.
Thanks Brian
oops my fault :o
Ok this would change things as a 250 on a 24vbat is good for 1600 the Classic 150 is the only one in the line up that could do this with one controller.
Ryan
But as you said above with 2 strings of 5 each one would be 36.1X 5 = 180.5 X 1.2 = 216.6 Volts.
The 250 would handle the volts
The output amps for the 250 is 62A at 24 volts. If my thinking is correct the panels are 8.21 A @ 35.1 Volts, I tie the 2 together at the combo box bring it to the controller at 216.6 Volts and 16.42 Amps would the output be 82.1 amps at 24 volts. So is the only way to do it, would be to be 48 volts 41.05 Amps at the combo box to the controller 24 volts 82.1 amps out making the 150 the only way to go? Is think correct or am I confused?
Thanks for your time as I try to get this right in my mine.
Brian
see post #3 here by boB it is a very good simple explanation of your problem
http://www.wind-sun.com/ForumVB/showthread.php?14351-Midnite-Classic-Maximum-Voltage
HTH
Ok, thanks it's starting to sink in here!! :D