vmpp@30.3v

jimbob01

is 30.3v vmpp on my sharp 235w panels to low an input voltage for my mstar tri 45?
do i need 2 in series so as to get a high enough input voltage for my 24v battery bank ?
panels are 4m away from c.c with 6mmsquare cable.
thanks jim

niel

Re: vmpp@30.3v

yes, that's too low as you'd need a vmp of at least around 35v and even 36v in very hot places such as las vegas or phoenix. 2 in series would cover the bases well. if you are using 3 of those pvs this would not be well suited as you would want to keep in multiples of 2 pvs in series. your cc could handle 2 paralleled strings of 2 in series.

jimbob01

Re: vmpp@30.3v

hi niel,thanks for the reply... so if i put 3 panels at a total of 114.9 ocv through 1 mstar 45 controller am i losing efficiency because of the higher input voltage needing to be reduced to 29 ishv .? jim

niel

Re: vmpp@30.3v

pretty much what i was going for was in keeping efficiency with 2 in series. you could use 3 in series if you wish as the efficiency drop won't be that detrimental or a game breaker. you certainly don't need the extra voltage to overcome any long distance runs as the extra voltage is usually needed in those cases to overcome voltage drops in the wires.

jimbob01

Re: vmpp@30.3v

ok..will go 2 panels in series .. thanks.jim

halfcrazy

Re: vmpp@30.3v

Jim
Question. Is this a MPPT Morning star or a PWM morning star? If it is MPPT, 2 in series is best. If it is PWM, 1 in series is best IMHO

Ryan

niel

Re: vmpp@30.3v

if it is a pwm cc then he should not have chosen the 60 celled variety of pv. 1 in series with a 30.3v vmp on a 24v battery bank will not function very well.