Hi everyone:
(first time post)

Apart from the price difference, why would someone not buy an MPPT charge controller? It seems to me that any increase in delivered power to batteries is worth it, compared to the traditionnal PWM chargers...
Does my question make sense? Anyone with experience on both types of chargers would like to comment?

Thanks.

p.s.: I really am surprised about the diversity of PV\solar topics on this site. Keep up the good work.

It makes sense to me to use MPPT for "serious" applications, but it's not necessary everywhere. For example, our family has a cabin on a small island that's only accessible by boat. We have a couple of panels to keep some batteries charged to provide lighting when we go there the odd weekend. The batteries can easily handle our needs for the time we're there and the panels will then have a lot of time to replenish the batteries. MPPT would be a waste of money in this scenario.

Granted, smaller MPPT's are still pretty cheap but not as cheap as regular controllers.

I sell and use both types. I prefer the MPPT cc's for the following applications:
- off-grid residential
- RV/campers
- remote instrumentation and monitoring

All of these are "serious" or mission critical and the extra amp-hours you get each day can add up to make a huge difference.

But, as with anything, your needs should dictate the solution. For example, if your idea of camping is to drive the RV out to the san dunes, then an MPPT may be overkill.

Thanks for your answers.
Makes sense.

I did some pretty secret stuff once and one of the design modes was if all the charging regulators went dead the default was a direct connect from panel to battery

Hi, most of what I have read talks about mppt cc's in cold weather. Does anyone know if there would be a significant difference here in Florida. I am about to grid tie 1kw of pv and already have a trace C40. It will be a 48v system. Inverter is an Outback GVFX3648 with battery backup, this is Florida after all.
Thanks, Rex

Hi Rexr,

MPPT would be especially good for you if you go with a 60V or 72V nominal array.

some mppt controllers have an extra advantage in that they can downconvert from a higher voltage and you won't see this in standard pwm controllers. this enables you to take 24v of pv and downconvert this to 12v. i would have to say the most versatile and flexible of the controllers would be the mx60 at this time. this can take the much higher voltages and can downconvert in odd configurations or from odd voltage pvs. to my knowledge this is the only one that can do this much for now.
the big drawback to using this versatile controller is that it can draw up to 8-10w just for the mx60 to operate so this is not generally good for 1 or 2 pv systems and in fact under 1kw systems may not be good in some cases. fear not as the person that designed this controller is at it again, but from a different company, midnight solar, and will be known as the classics. the drawback is it's still being designed and won't be available for some time yet. i have been told it will have many improved features that isn't a good idea to forwarn the competition about, but it was publicly disclosed it will have improved draw characteristics so that those smaller systems will run more efficiently on it.

Rexr,

I have a C60 and been using it for about a year 12 volts in and 12 volts out. It has been a great unit. However I am using #4 wire from my panels to the controller which limits me to about 33 amps. I could have bought bigger wires but no need. I just up my panel voltage to 24 using the mx 60 and kept the 12 volt battery bank. So now I can have twice as many panels and not spend the cash for the wire.. I plan to up the voltage with more panels and hold the same input amps. Keeps me from having to buy 4/0 wire and I can expand. And the MPPT to the battery bank is 2 amps higher than what is going in. I have been having lots of cloudy days so the MPPT helps. Plus using a higher input voltage will wake the charger up earlier and start charging sooner same thing at night. It will stay awake longer.

The 8 to 10 watts niel is talking about can be adjusted a little by changing the the shutdown input amps setting. Set it to <.8 amps and it will shut down when the sun light is too low to cover it's usage. However <.8 amps is at 12 volts. And I think I remember someone said the less power the MX 60 is putting out the less power it uses as well.

I would like to hear more on the Classic but guess we will have to wait.