Cheap MPPT regulator from China - true and not fake?

[SunEagle]

True. It is nevertheless lost as a result of using the PWM controller. So we could say that it is lost by the PWM controller even if not lost in the PWM controller.

Or in other words "a percentage of what the panel wattage can produce is not being used by the CC to charge the batteries". I would put the blame on the PWM CC for the loss.

[sdold]

I think those are good explanations. It reminds me of an engine that isn't allowed to turn up to max power rpm.
I'm sure there is a reason for 36 cell panels, but it seems like fewer cells in a smaller panel would be a better match.

[SunEagle]

I think those are good explanations. It reminds me of an engine that isn't allowed to turn up to max power rpm.
I'm sure there is a reason for 36 cell panels, but it seems like fewer cells in a smaller panel would be a better match.

Probably the "plus" side of 36 cell or "battery" panels is the ability to move them due to their size and weight. They allow you to build a small power center which can be easily broken down and moved. That is the one reason I built a system so it could be easily moved via my pickup or stored in my RV.

Then again while having mobility as a "plus" the big negative is the cost/watt. Also finding the "right" CC that matches up with those panels can be difficult.

[Sunking]

I think those are good explanations. It reminds me of an engine that isn't allowed to turn up to max power rpm.
I'm sure there is a reason for 36 cell panels, but it seems like fewer cells in a smaller panel would be a better match.

Actually in the early days panels were only 32 cells for direct connection to batteries. Coleman still makes the mechanical relay on/off controllers for them. Shell Oil was the big name for them back in the day and the day and still in use today. Next time you drive down the road and see a blinking light with a solar panel chances are it is a 32 or 24 cell panel directly connected to a battery with only a Diode (Blocking) to prevent back feeding from battery at night graining the battery. Once PWM hit the market panel manufactures settled on 36 cells 18 volt as standard 12 volt battery panels.

Moral of the story rather you use PWM or direct connection you turn a 100 watt panel into a 66 watt panel. Only MPPT will allow you to use all the potential power from a panel. Once you go above 200 watt panel power using GT panels and MPPT is less expensive. It takes a 300 watt PWM system to = a 200 watt mppt system. A 300 watt PWM system will run you around $650. A 200 watt mppt much less around $400.

Only reason PWM and battery panels are still around is PT Barnum Effect. A Sucker Born Every Minute and the world is full of them with pockets full of cash.

[sdold]

Dereck, do you know if MPPT controllers are any less likely to generate RFI? We tried a few PWM controllers at some sites and they generated a lot of noise on 42 and 150 MHz.

[Sunking]

Dereck, do you know if MPPT controllers are any less likely to generate RFI? We tried a few PWM controllers at some sites and they generated a lot of noise on 42 and 150 MHz.

They are both equally noisy as both use switching. Just a matter using a good controller with adequate filtering.

[bcroe]

Dereck, do you know if MPPT controllers are any less likely to generate RFI? We tried a few PWM controllers at some sites and they generated a lot of noise on 42 and 150 MHz.

The PWM controllers are inherent noise generators, because they rely on switching panel
current on and off. Then the panels act as a big antenna to radiate the noise. To a lesser
degree any other wiring will also radiate. Only a limited amount of filtering may be used
before causing too much heat.

An MPPT controller runs at high frequencies that can easily be filtered, if the mfg takes the
expense to do so. Current through the panels and other wiring should be essentially DC,
so radiated noise should be minimal. Failing that, external shielding & filters can be added
to this equipment to limit radiation. Bruce Roe