Solar Charge Controller question
Here's my set up: 2018 Coachman Viking 17BHS 21' Dual 6v batteries Solar panels: 2 Nature Power 100 watt Polycrystalline panels Tolerance: 3% Voltage at Pmax(Vmp) 18.0V Current at Pmax(Imp) 5...
Forum Discussion
pianotuna wrote:All I did was give an example of performance for a PWM vs MPPT for an example 100W 20V solar panel. I didn't put a cost comparison..just a technical operating difference. Those were factual numbers....not an opinion. You have to decide for yourself if it's worth the cost difference....which in my opinion is a pretty low difference.
babock,
You have offered an opinion.
Folks want to see studies that prove MPPT works better than PWM.
An ideal study would compare the payback time for the difference in cost.
For example, in 2005 my system panels cost was $5.50 per watt. Going to MPPT saved on the cost of the system, making a zero price difference between MPPT and PWM, at $1700.00. In 1990 I had a 30 watt system--which cost about $1700.00
Since then the price of panels has dropped precipitously but charge controllers not so much. The lowest price was, before artificial tariffs were introduced $0.36 cents per watt, retail.
That makes it cheaper to add another panel rather than switching to an MPPT controller, provided there is room on the roof.
So, today, my system would have a fully featured PWM controller rather than MPPT, if cost were the only criterion. But cost is not the only factor, and the price of a large capacity controller is a one time cost.
If the roof has no more room left, then MPPT to gather every erg of power may make sense.
My dream system would have remote actuators for tilt, and an MPPT controller with a system input voltage of at least 70 volts, and 2000 watts of panels.
So I suggested you to present a study that proves your opinion.
If you don't understand how PWM and MPPT work, I really can't help you with that. A PWM's max output current is the max current of the panel. An MPPT is a DC to DC converter which can convert 98% of the power collected. For example, 100W/14V x.98 = 7A. The PWM 100W will output 5A if it is a 20V panel. Can't make it any simpler than that. No links needed...it's just the math. If you can't figure out the simple math I just posted, not sure what to say to you.
