Solar-Panel to Controller Loss
Much has been made of the lower losses on the panel to controller path with MPPT because the amps are less. So once you have your loss measured, how valuable is it to improve on that if you don't lik...
Forum Discussion
EDIT I just remembered about those buck converters where input voltage had to be at least 1 volt above output voltage
http://www.ebay.ca/itm/DC-DC-Adjustable-Buck-Converter-4-5-30V-to-1-2-29V-15A-Step-down-voltage-Module-/251961012008?pt=LH_DefaultDomain_0&hash=item3aaa0bef28
But when I was at the 30v on the 24v I was using the Solar30, which does not have a buck converter and no Vmp to worry about either.
---------------------------
Ok, but Voc is at the bottom of the IV curve where I got that 45C/35. Anyway, we did that earlier for the power coefficient, where my 255 at 45C vs 25C loses 20 times 0.43% = 8.6%= 22w to 233W.
I see how the top of the knees go left to lower voltages with higher temps so that is the Vmp getting lower in voltage. Current holds ok going left but the lower V makes lower INPUT watts to the controller.
I am confused about where along the Vmp is so low you can't charge the battery to 30v anymore. Help! :(
EG at 800 and 45C (NOCT list of specs), you get INPUT 185w, (no line loss) (27.5v x 6.71a) and if controller is 95% eff then OUTPUT watts is about 185 -9 = 176w and divide that by 30v = 5.87 amps
Why can't 5.87 amps charge the battery at 30v ?
To get no amps at 30v, watts would have to be under 30w output and 31.5w input. That would be a really hot panel!!!! But it could easily be a low light situation to have watts that low.
Help!
http://www.ebay.ca/itm/DC-DC-Adjustable-Buck-Converter-4-5-30V-to-1-2-29V-15A-Step-down-voltage-Module-/251961012008?pt=LH_DefaultDomain_0&hash=item3aaa0bef28
But when I was at the 30v on the 24v I was using the Solar30, which does not have a buck converter and no Vmp to worry about either.
---------------------------
Ok, but Voc is at the bottom of the IV curve where I got that 45C/35. Anyway, we did that earlier for the power coefficient, where my 255 at 45C vs 25C loses 20 times 0.43% = 8.6%= 22w to 233W.
I see how the top of the knees go left to lower voltages with higher temps so that is the Vmp getting lower in voltage. Current holds ok going left but the lower V makes lower INPUT watts to the controller.
I am confused about where along the Vmp is so low you can't charge the battery to 30v anymore. Help! :(
EG at 800 and 45C (NOCT list of specs), you get INPUT 185w, (no line loss) (27.5v x 6.71a) and if controller is 95% eff then OUTPUT watts is about 185 -9 = 176w and divide that by 30v = 5.87 amps
Why can't 5.87 amps charge the battery at 30v ?
To get no amps at 30v, watts would have to be under 30w output and 31.5w input. That would be a really hot panel!!!! But it could easily be a low light situation to have watts that low.
Help!
