wiring panels

Discussion in 'Off Grid Living' started by rsbhunter, Feb 12, 2012.


  1. rsbhunter

    rsbhunter Monkey+

    If I am setting up my system for 24 volt, and using outback MPPT controller,if the panels are30 volt,I would want to wire each panel parallel,right? Thanks,rsbhunter
     
  2. BTPost

    BTPost Old Fart Snow Monkey Moderator

    That would depend on the wire size, and length, between the Panels and the OutBack Controller. You run into I2R losses, if you try and force to many AMPs, down to long, and, or to small, of wire. Those losses can be significant. So, what you need to do is figure what size of wire, the maximum length, and expected Current (AMPs) carried, and make an intelligent decision, on what the Panel Buss Voltage should be, taking into consideration the Maximum Input Voltage that you might get, in Full Direct Sunlight, on a very cold Day, so you do not exceed the maximum Input Voltage Spec of the Controller. If that doesn't mess with your Brain, you will do fine..... ..... YMMV....
     
    Nadja likes this.
  3. TnAndy

    TnAndy Senior Member Founding Member

    The panels need to be about 33-35v (Vmp) actually.....30v would be right at the threshold of not having enough to charge WHEN you finally get TO the batteries, due to the reasons Bruce listed above.

    The simple solution is to wire in pairs, or threes, or fours....up to the input limit of the charge controller ( which is 150v on Outback ), less de-rating for the most extreme cold conditions in your area, which will knock you back down in the 120v area.

    Also, when you figure that voltage, you use the higher Voc number.....voltage open circuit.....the max the panels will ever produce....not the lower Vmp.....which is the "normal" max produced at max power point.

    Also, by wiring in strings ( 2,3,4 ), that ups your voltage and lowers your line loss between the panels and the charge controller.....a good thing.
     
  4. larryinalabama

    larryinalabama Monkey++

    Just curious... what would it take to run a 1500w space heater, a 5000btu ac window unit, and 3 15w light bulbs?
     
  5. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    O Great One's charge account ! You do not want to even attempt to go there.
     
    BTPost likes this.
  6. TnAndy

    TnAndy Senior Member Founding Member

    While I agree with Nadja, a LOT, to really quantify "a lot", it would take more information.....biggest one being the TIME element.

    Watts are an instant measurement of electrical flow, but power is how many watts over how much time ( usually an hour ), so if you run a 1500w heater for one hour, you would use 1500watt/hours, or 1.5 kilowatt/hours......about 15 cents worth of electricity in your neck of the woods.

    The AC is a more complicated story. 5,000BTU doesn't mean much when it comes to power used. You'd have to know, again, the wattage, or at least the volts/amps so wattage could be calculated, and THEN, you'd have to know is it running full power for how long, or just fan for how long, and so on.....really, the only good way to tell is plug it into something like a Kil-a-watt meter and record the use for a few days or weeks.

    Even then, it would be a bit of guess, because the run time is gonna depend on the temperatures outside, how well the room is insulated ( my run time would likely be different from your run time ), and so on....
     
    larryinalabama, Nadja and BTPost like this.
  7. rsbhunter

    rsbhunter Monkey+

    Panels

    This is the info on the panels: Candian Solar's Newedge CS6P 235 Watt Solar Panel I wish i knew enough to know , but i AM paying attention to all of you that DO know!!! Thanks a million, and change...rsbhunter
    <TABLE border=1 cellSpacing=0 cellPadding=3 sizset="0" sizcache="9"><TBODY sizset="0" sizcache="9"><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Nominal Maximum Power at STC (Pmax):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>235W</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Optimum Operating Voltage (Vmp):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>29.8V</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Optimum Operating Current (Imp):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>7.9A</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Open Circuit Voltage (Voc):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>36.9V</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Short Circuit (Isc):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>8.46A</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Operating Temperature:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>-40°C ∼+ 85°C</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Maximum System Voltage:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>600V (UL)</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Maximum Series Fuse Rating:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>15A</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Power Tolerance:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>+5W</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Temperature Coefficient Pmax:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>-0.43% / °C</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Temperature Coefficient Voc:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>-0.34% / °C</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Temperature Coefficient Isc:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>0.065% / °C</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Temperature Coefficient NOCT:</TD></TR></TBODY></TABLE>
    <TABLE border=1 cellSpacing=0 cellPadding=3 sizset="0" sizcache="9"><TBODY sizset="0" sizcache="9"><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Nominal Maximum Power at STC (Pmax):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>235W</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Optimum Operating Voltage (Vmp):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>29.8V</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Optimum Operating Current (Imp):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>7.9A</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Open Circuit Voltage (Voc):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>36.9V</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Short Circuit (Isc):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>8.46A</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Operating Temperature:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>-40°C ∼+ 85°C</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Maximum System Voltage:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>600V (UL)</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Maximum Series Fuse Rating:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>15A</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Power Tolerance:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>+5W</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Temperature Coefficient Pmax:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>-0.43% / °C</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Temperature Coefficient Voc:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>-0.34% / °C</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Temperature Coefficient Isc:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>0.065% / °C</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Temperature Coefficient NOCT:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>45°C</TD></TR></TBODY></TABLE><TABLE border=1 cellSpacing=0 cellPadding=3 sizset="0" sizcache="9"><TBODY sizset="0" sizcache="9"><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Nominal Maximum Power at STC (Pmax):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>235W</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Optimum Operating Voltage (Vmp):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>29.8V</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Optimum Operating Current (Imp):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>7.9A</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Open Circuit Voltage (Voc):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>36.9V</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Short Circuit (Isc):</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" align=middle>8.46A</TD></TR><TR vAlign=top><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px">Operating Temperature:</TD><TD style="PADDING-BOTTOM: 5px; PADDING-LEFT: 5px; PADDING-RIGHT: 5px; PADDING-TOP: 5px" colSpan=2 align=middle>-40°C ∼+ 85°C</TD></TR></TBODY></TABLE>
     
    larryinalabama likes this.
  8. rsbhunter

    rsbhunter Monkey+

    wiring

    So, would i want to run 5 banks of 2 panels wired in series, to the jct box, then parallel, then to the controller? rsbhunter
     
  9. Nadja

    Nadja RIP 3-11-2013 Forum Leader

    I would run 2 banks of 5 panels ea to ea charge controller. Wired in parallel, that is positive to positive on each panel and neg to neg.
     
    rsbhunter likes this.
  10. TnAndy

    TnAndy Senior Member Founding Member

    Nope.....2 "banks" ( called strings in the solar biz ) of 5 panels would exceed the input limit on an Outback charge controller.

    For the second or third time:

    Take the Voc.....36.9......multiply times 5....you get 184.5v BEFORE you start de-rating for temperature. The max in on Outback charge controllers is 150v, uncompensated for temperature.

    The REAL limit is about 120v in Colorado Mtns, where my guess is the max low is around -20 or so.
     
    Gafarmboy and BTPost like this.
  11. larryinalabama

    larryinalabama Monkey++

  12. TnAndy

    TnAndy Senior Member Founding Member

    I'm like you, Larry, I'd be interested in the price.

    Since they are selling it as a "solar" unit, my guess is the price is jacked about 50% over the same price as an 18,000 BTU ( which is a 1 1/2 ton unit ) AC model. You can buy the equipment only for a single point system like this for under $2,000.

    I have that size "mini-split" system in my house, Mitsubishi brand....does a real good job cooling the main area of the house. I didn't put AC in when I built the house, and later, this mini-split ductless system was the easiest way to go adding AC. Mine is about 10 years old, and the SEER rating is only about 12.....they have new ones up in the mid 20 ratings that actually use inverters to change the AC into DC at the unit, so it isn't much of a leap to simply make the whole unit DC.....and I'd think if you were gonna make a "solar" version, you'd get the SEER rating well above the 18 that one has.

    Fujitsu, for example, makes a 26 SEER rated unit that uses an inverter. The advantage of the inverter ( AC back to DC ) is it's easy/efficient to vary the speed of the compressor to match the exact cooling/heating load requirements.

    Even though I added mine after the fact, I think if I were building new, I'd consider mini-split systems over a 'standard' duct system. Cost, for one thing, is a lot cheaper. SEER ratings a lot higher. AND you can cool/heat ONLY the area you want in zones.....why treat (and pay for) the whole house as one zone ( like typical ducted systems do ) if you're not USING the whole house at one time ?
     
    larryinalabama likes this.
  13. larryinalabama

    larryinalabama Monkey++

    My centural AC still works fine but it old and innefficent. I find it may be eaiser to heat and cool the rooms of the house and may try to add solar power to one room. I dont mind lighteng the wood stove but its a hassele unless its cold and Im home for a few days, and it is not worth a crap at cooling. Updating th centural unit isnt cheap and neighter is the solar option, Im just trying to get an idea if it would even be worth it.
     
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