ShutterStuff
Port Angeles, WA USA
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Almot wrote:What Mena said - get controller for maximum power that you're planning. Or you'll spend money on 15A PWM and then some on cables appropriate for this current, and some sweat. Then you'll get more panels and discard the first controller, and possibly - the cables that you've pulled through, and start pulling thicker cables.
I only have room on the roof for 1 panel. I just want to supplement the batteries while driving and the kids are using power and I am not running the generator.
That said and with what you and Mena said above, my best bet would be this controller:
Morningstar SS20L-12 SunSaver 20
Then I would be done with it.
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pianotuna
Regina, SK, Canada
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Hi,
Yes, go with the Morningstar--and forget about the MPPT options. If you are not adding another panel a 10 amp Morningstar will be enough controller for you.
Regards, Don
Kustom Koach Class C 28'5" 256 watts Unisolar, 875 amp hours in two battery banks 12 volt batteries, 2500 MSW watt inverter.
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ShutterStuff
Port Angeles, WA USA
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Thanks! You have all helped my solar education and I am ready to tackle this in the next month or so.
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bogen2
Edmonton
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You may want to consider the Prostar PS15. Its only $15 more but provides 3 stage charging which I don't think the SS20 does. Its 5A less capacity but with a single panel you should be fine.
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Almot
Vancouver BC
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There is no need in 20A controller. 15A should be enough. This is 145W panel, with 14V output the current is 10.1A assuming zero losses, so in reality it will be less than 10A.
BFL13 is correct, there is this "cloud edge effect", when edge of cloud is passing, causing momentary surge in output current. Controller will cut off the excess current if this happens. This burst can be about 20% above the nominal panel power (2A in the OP case), but it doesn't last long.
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smkettner
Southern California
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Isc is 8.37 amps. See specs in above link.
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BFL13
Victoria, BC
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Isc is taken at 25C so when cooler you can get a little more. Eg, my panel is rated 8.2 but will sit at 8.3 or 8.4 on cool days.
My controller lets the amps through if they get over 16a, as seen last year when I had two panels and with clouds I saw 19amps (Trimetric) so it does not cut off the amps if over its rating. It might get warm or hot if the overage lasts, but with cloud effect it doesn't last. Some controllers do cut off the amps AFAIK.
That controller says it is series not shunt. I am unclear on the difference for how they regulate the voltage, but either will work fine for the OP's purpose
You don't need three-stage charging for that job, just a voltage limiter. If anything like how ours goes, you will not get the batts all the way full before dark anyway.
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smkettner
Southern California
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Morningstar Sunsaver SS-10L-12V controller is rated for 25% overload.
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Almot
Vancouver BC
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Isc of the panel is 8.4A before controller, but after the controller it will be maximum 10A charging current at 14V (except for periods of edge effect). Or does it just pump out whatever voltage comes in from the panel?
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BFL13
Victoria, BC
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The controller voltage at its battery terminals will be the same as the battery voltage. When SOC rises to where the controller starts to control starting when battery voltage reaches the controller's upper set-point, the voltage then bats back and forth between upper and lower set -points (mine has a 0.8v spread 13.5-14.3
Mine goes into an on off routine with duration of On time reducing and Off time increasing. while others stay on but taper the amps which is considered to be a more refined method (I doubt the batteries can tell though)
To read panel voltage you have to remove the panel wires from their controller terminals and read across the ends of those wires.
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