Morningstar TS-45 or 60?

[EXPO365]

So it looks like we'll be getting 4 Interstar GC2-XHD-S batteries for the house bank setup for a total of 464 amp hours. I want to go with the Morningstar MPPT. I'm wondering if I should go with the 45 or the 60?

I think we'll be mounting two 100w panels with another two more later down the road.

 

[workerdrone]

Not sure I'd pay extra for mppt either if I had only 100w panels.

 

[dwh]

Not sure I'd pay extra for mppt either if I had only 100w panels.

The panel size doesn't matter, it's the array total that matters. He's talking about having a 400w array. MPPT would be worth it.


EXPO365,

The battery bank size has nothing to do with it. The charge controller has to be able to handle the amps output of the solar array. As Verkstad pointed out, 400w / 12v = 33a.

BUT...

You have to do the math based on worst case. So let's say the batteries are "dead" at 10.5v. So 400w coming in from the array and going out at 10.5v would be 38a. Build in a little overhead for cold clear weather when the solar array might actually produce MORE than its rated 400w and the TS-45 is still big enough to handle it.

 

[workerdrone]

Thought it was the array voltage, not the current, that determined how much you'd gain from MPPT. In my case, I had 4 100w panels in parallel so I could maintain decent performance with one or more panels shaded. 12V Renogy panels.

 

[unseenone]

If I did it again, I would have done the 60.. Just for the extra capacity. The 45 has been stellar though, so you can't go wrong with either one, unless you are planning on running Ham radio while charging..

 

[dwh]

Thought it was the array voltage, not the current, that determined how much you'd gain from MPPT.

The MPPT will load the array down so that it operates at whatever the "Vmp of the moment" is. That gets the most watts out of the array. That's the first advantage of an MPPT controller.

(If you didn't have the MPPT, then the array voltage will always be at whatever the battery voltage is - and that sure ain't gonna be anywhere near Vmp.)

Then the controller will take the higher voltage/max wattage power from the input side and feed it through a buck converter to lower the voltage, which has the handy side effect of also bumping up the amperage to get more amps headed to the battery. That's the second advantage of an MPPT controller.

Then the output from the buck converter runs through a PWM circuit to charge the battery. That's not technically a beneift, but still a good way to charge a battery.


But the array voltage doesn't matter to the MPPT. The array voltage must always be higher than the battery voltage or the battery won't charge. The MPPT will optimize the loading of the array so the array operates at its most efficient voltage (which will get the most watts out of the array), regardless of whatever voltage the array is rigged for. So series or parallel - either way the MPPT will get the same watts from the array.

Vmp is a constantly moving target. MPPT is constantly adjusting the load, to keep the array operating at whatever Vmp is at the moment. Most do a check and adjust every 60 seconds.


So then it just becomes a question of: "Is it worth the extra cost?" Rule of thumb is for less than 200w - probably not worth it. 200w or more, certainly worth the money.

 

[unseenone]

I'm doing 24v with mine, it's good

 

[Kiomon]

Only thing I can think of is if you want any of the networking features of the 60. The 60 has an ethernet port and allows you to easily log in to download historical performance and program the unit easily. We are data geeks though.