is mppt worth it?

[solarsam12345]

Hey,
On a small system (50w of solar, 36ah battery) is buying a mppt controller over pwm worth the money?
Thanks, sam

[jony101]

to your answer no. Even though i heard that there were no advantages on small panels, i had to see for myself and bought both pwm and mppt to try and get the most power on my first solar panel.

I found out mppt needs high voltage panels, from my expierence I would say at least 30 volts. As an example I had a 120 watt panel which was rated about 21 volts output and 7 ipmax. I tried it with both pwm and mppt. And I actually got better performance with the pwm.

120 watt with pwm = 7 amps
120 watt with mppt = 6 amps

Doing the same test with a 240 watt panel rated at 34 volts and 7 ipmax
240 watt with pwm = 7 amps
240 watt with mppt = 12 amps

But one thing I have seen on youtube is someone connect 4x15 watt solar panels (in series) from harbor freight to an outback mppt, he was getting 6 amps of power. So from that video i would say that if you connect 2 or more small panels in series and the voltage equals over 30 volts maybe you will get better performance than a single large low voltage panel.

A 20 dollar pwm controller will work just as good if not better than a 100+ dollar mppt controller on a single low voltage panel according to my real world tests.

[sensij]

Without including model numbers of the controllers involved, I don't think I'd make any design decisions based on those results. The "is it worth it" question sort of depends on how much you are discharging the battery and how many hours of sun you have to recharge it. If PWM will get enough energy back into the battery to get it to float, then no, MPPT may not be worth it.

[Sunking]

Assuming you use a real quality MPPT charge controller, then no in your application. It does not pay for itself below 200 panel watts.

It takes a 300 watt PWM system to equal what a 200 watt MPPT system can generate in a day. When you use PWM controllers forces you to use expensive battery panels on the order of $2/watt. So for a 300 watt PWM system you are looking at a $600 panel and a $50 PWM 20 amp PWM controller for a total of $550 to $650.

Grid Tied panels are much less expensive at $1/watt and MPPT controllers are expensive. So a 200 watt grid panel cost $200, and a 20 amp MPPT controller will cost you $200 for a total of $400 to $450.

Both systems deliver up to 17 amps.

[solarsam12345]

thanks fo helping

So thanks to everyone who replied,
I will not upgrade to mppt on my system.

Sam