MPPT Controller Needed?

MEXICOWANDERER wrote:
High voltage panels are much cheaper to make. Can you imagine panels where TWELVE AMPERE rated cell to cell distribution printed power circuit tracings are required? The cost would be astronomical.

No I did not realize going 9.26 to 12 amps would be astronomical.

rjxj wrote:
I would think about building a system based on what you may want some day vs a part that you can get a deal on now.

That's the thing - most people don't know what they may want some day.

Energy audit goes first. There are dozens of load calculators. Or use battery monitor if you have one.

Then - bank size and array size, then - controller. If panels that are on sale, fit your criteria, then you are in luck. If not, then man up and pay. Panels - even at fair market price - are less than a half of total parts cost.

Multiply the results of audit or array size by 1.3-1.5 to account for possible future needs, and try being honest when considering how often you park in shade. PVWatts Solar Calculator will tell you average monthly harvest for a given array and given location, divide by 30 for a daily harvest. This assumes no shade.

I have a 185W high voltage panel and a Morningstar MPPT controller. There are distinct advantages to high voltage panels, usable current from sun up to sun down and in a shaded camp site (not a lot, but some).

Look at your roof and consider future expansion if you are building on large 24 volt panels. Price 12 volt panels and how they fit and the price of a quality pwm. Also consider prices for a monitor if you want the monitor on the wall inside instead of dip setting down at the controller. I would think about building a system based on what you may want some day vs a part that you can get a deal on now.

Thanks for the replies. I thought a MPPT controller would be needed and you all confirmed that.
Now to find out DS's price on the panel and a MPPT controller.

Yes, you need MPPT with that one unless you want to waste nearly half the power. The potential power from ANY solar panel is simply Imp x the operating voltage. If you hook this panel to a 12v battery with a PWM controller the voltage might be around 14v. That's 8.55 A Imp x 14 v = 120 watts.
You could do that but why? With an MPPT controller you will be able to get the full 265 watts from the panel because the controller will allow it to operate at just the right voltage for maximum output under any conditions.

MEXICOWANDERER wrote:
Without question. YES. In order to get ANY "reasonable" amount of power not just maximum power.

x2.

PWM with 24V array on 12V bank would get you only half of total available power.

MEXICOWANDERER wrote:
Can you imagine panels where TWELVE AMPERE rated cell to cell distribution printed power circuit tracings are required? The cost would be astronomical.

I can't imagine.

Without question. YES. In order to get ANY "reasonable" amount of power not just maximum power.

12 volt panels (Like my Kyoceras are 21.1 volts open circuit. Others were 17.1

High voltage panels are much cheaper to make. Can you imagine panels where TWELVE AMPERE rated cell to cell distribution printed power circuit tracings are required? The cost would be astronomical.

I did a project in 1999, that was located 170' from the batteries. Because of the voltage drop I had to use series panels with about 60voc. By the time they got to the batteries the poor voltage measured around 25. The owner was shocked he had to build another battery and inverter shed right at the panels. On top of it all, I had to boost the 120vac to 480vac for that football field length run to the house (a 2nd transformer). Don't ask why things were laid out the way they were.

Yes, though there are those that would argue that it isn't worth the cost. An MPPT gets the max out of the panels that it can.

Rouge Energy has their MTP-2024, good for 20amps, well under what will be doing with 265W for about $225. I have the older 30 amp version of the same controller that I paid almost $400 a number of years ago, but that one is no longer in production. Marc (Rouge owner) is great to work with, too.