Solar Questions, yes more solar questions
Okay, before you say it, I did search, and have been reading on this for days. Here is my question. I have a bonus coming possibly and am trying to decide if I want to use it for solar on our ...
Forum Discussion
KE6IRJ wrote:
Am I on track?
More-less.
The audit is flawed, but yes, you need about 300W solar. Won't hurt getting more, for rainy days. Converting to LED is almost mandatory with a small solar.
Proper audit:
(watts)*(run time of EACH DEVICE SEPARATELY) =daily watt-hours. This is the minus side of the balance sheet.
The plus side is more complicated. As a rule of thumb, solar harvest in watt-hours = (panel wattage)*5 hours.
Those Ebay panels Link
are unknown stuff, but this is not uncommon. The industry is in disarray, reputed brands disappear. Everybody seems to cobble up panels in their back yard. I don't even see established Chinese brands like Trina anymore, not to mentioned old US and German brands. I don't like it being Monocrystalline, would prefer Poly, but the price is good with free S/H.
30A PWM is dangerously small for 3*160W.
2*160W have 18A current, so with 20% safety margin you need 21.5A PWM, the closest bigger size is 25A. If you add 3rd panel, you'll need 35A.
For a 35A PWM consider Xantrex aka Trace aka Schneider, with their optional remote temp sensor. Plus, digital Drok voltmeter. Don't be tempted with $4 meters on Amazon, Drok is about the only accurate meter. Or get Xantrex meter, costly but nicer. I wouldn't want bright LED display in the night.
As noted, you can also use MPPT, they are more expensive but will simplify the install as you will be able to wire panels in series and run same MC4 #10 cable to controller, without junction box. You can wire in series either 12V or 24V panels, it doesn't matter for MPPT, though 24V are cheaper. OTH, with PWM you are limited to parallel wiring, i.e. rooftop junction box and thicker cable.
