Another power controller question

Ron,

I believe that the MP3129 is rated at 20 amps. 240 W of panels won't deliver much over 15 amps, so the controller should handle the two panels ok with a reasonable safety margin.

Cheers

John

I would be asking why a 120 watt (~7 Amp) solar panel won't run an Engel fridge

Do you presently have the second 120 watt panel ?

Maîneÿ . . .

No we dont have the second pannel yet..... the pannel we have will run the fridge but it draws a lot from the batteries when its on freeze most of the time

ronrox

Hey Ronrox,we have a similar setup to what you want.Go with 2x 120w panels,
set them up in the morning pointing somewhere north,go and spend the day doing what you want to do,come back and find your batteries fully charged.No having to hang around camp all day moving panells to follow the sun.Our engle is a 60 litre and it was used as a freezer all the time for six months,never missed a beat,never had battery problems.This is our experience from a practical point of view.(This was across northern Australia,)Not familiar with your controller but if as others have said it can handle 20amps then it will handle another panel.

ronrox,
to use only 'numbers' to ascertain the fridge and solar panel equations you have to know what those numbers truly represent.

Stated *simplistically* the fridge (not freezer) will be running part time, on a duty cycle of about 50%, (mine is only 33% - 20 mins per hour, for comparison purposes only) so if your fridge is on every second half hour and at the same time your solar panel is on 100% of the time (not 50%) then in the time the sun is shining the battery remains fully charged.

Using a fridge as a Freezer, the duty cycle will be slightly longer, but once frozen it will be easy to maintain frozen, because the freezer is not opened as often as a fridge and maintains temp.

Only in the evening when the sun is not shining, supplying the power to maintain the battery, will the fridge or freezer be taking power that is not being replaced.
However in this time the duty cycle is also shorter, because the ambient temp is also lower.

Hope this assists you

Maîneÿ . . .

"Will our charge controller Powertech MP3129 handle this"

Yes

"should we upgrade to a larger charge controller"

No.