Solar wiring question

Morning everyone,

Ok so I recently purchased a 140w solar kit from bit_deals. I am currently looking at replacing the stock regulator and wiring but I have some questions I'm hoping people can answer for me.

The solar panels will be powering a 110ah agm in a battery box. The box is fitted with two Andersons. I will be mounting the regulator on the side of the battery box.

Originally I had been planning on running cable from the regulator to one of the Andersons and then from the other Anderson to the fridge. But now I am aware that you can run the fridge and other accessories from the load terminals on the regulator. Is there any benefit in doing this? Also if I were to do this would this simply mean that the positive and negative wires from the fridge would just run strait off the load terminals on the regulator and not need to be connected to the battery directly at all??

Sorry for all the questions, I am just a bit new at all this solar/12v stuff.

Ps we can assume that I will be using either a Steca 2020 or one of the 20a Juta MPPT's.

Any help is appreciated.

Simon
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Reply By: Member - Troll 81 (QLD) - Friday, May 04, 2012 at 08:06

Friday, May 04, 2012 at 08:06
I would run the fridge straight from the battery.
AnswerID: 484938

Reply By: Battery Value Pty Ltd - Friday, May 04, 2012 at 08:37

Friday, May 04, 2012 at 08:37
Hi Simon,

as long as the fridge current remains below the specced max output current of the solar regulator, you could use its load terminals to take advantage of the solar regulator's built in low volt cutout function.

But if the fridge already comes with a low voltage cutout built in, it's better to wire it up to the battery terminals.

BTW none of the two solar regulators you mentioned are true MPPT units.

True MPPT solar regulators can achieve higher charging amps especially under cool/cold ambient temperatures.
Another advantage of a true MPPT solar regulator is that you can wire the folding panels in series for minimum power loss in the wires, and greatly improved tolerance to partial shading.
E.g. in a typical 2x12V folding panel situation you lose 50% of charging amps versus only 25% if only one cell gets shaded out (a leave or similar may land on it when panels are sitting on the ground).
This youtube demoshows how a true MPPT solar regulator can reduce the effects of partial shading on the solar panels.

cheers, Peter
AnswerID: 484942

Reply By: P2D2 - Friday, May 04, 2012 at 17:56

Friday, May 04, 2012 at 17:56
Morningstar Prostar 15A or 30A is a precision solar regulator with inbuilt temperature regulation. Morningstar are no 1 in the world for all the right reasons. www.morningstarcorp.com
Steca like Plasmatronics are dinosaur negative regulation technology from antique telephone exchanges.
AnswerID: 484960

Follow Up By: Member - Ed C (QLD) - Friday, May 04, 2012 at 19:56

Friday, May 04, 2012 at 19:56
The ProStar models are PWM controllers, are they not??

I'm using a (Morningstar) SunSaver SS-MPPT-15L

More than adequate for 140W panels


:)

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....Not necessarily mechanic!!"

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Reply By: Member - Phil G (SA) - Sunday, May 06, 2012 at 10:07

Sunday, May 06, 2012 at 10:07
Won't work.
The initial current is too high when the fridge tries to cycle.
The output of your solarpanels will drop when a cloud comes over.
Some fridges (eg engels) warn you to connect direct to the battery for the health of the compressor.
Other fridges have low voltage cutouts.
So for many reasons, you'd end up with warm beer and no advantage.
AnswerID: 485113

Follow Up By: Member - Ed C (QLD) - Sunday, May 06, 2012 at 14:58

Sunday, May 06, 2012 at 14:58
Phil, I think you'll find the load terminals on most (if not all) decent solar charge controllers are powered direct from the battery, not from the solar input..
(if not connected to a battery, the reg. she no work;-))

As pointed out above, when loads are powered from these terminals, the regulator acts as a very effective low voltage cut-out (cut-out/ cut-in voltage adjustable on many), so IMO, any 'fridge which does not have it's own low voltage cut-out (e.g. Engel) would be better powered from said load terminals..
(Won't make any difference while the battery remains charged of course...)

Catch ya later.... Ed C

:)

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Follow Up By: Member - Phil G (SA) - Sunday, May 06, 2012 at 17:57

Sunday, May 06, 2012 at 17:57
Gday Ed,
Always appreciate your input. I wasn't aware that current could also be drawn from the battery when connected to the load terminals of the regulator.

But I have had a read of the instruction manual from your morningstar regulator. They don't mention the word "fridge" anywhere in the "load" section. I'm guessing that the initial current surge from some fridges still triggers the low voltage cutout of 11.5V (at the regulator) and remains cut out until it hits 12.6V. I'm suggesting that its still not a good idea to hook a fridge to the load terminals. What do you think?

Cheers
Phil

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Follow Up By: Member - Ed C (QLD) - Sunday, May 06, 2012 at 20:00

Sunday, May 06, 2012 at 20:00
G'day Phil,
You do make a good point re start-up current from some 'fridges triggering the low voltage cut-out, and I have no issues with your stance on this, though with respect, I'd suggest the same might apply with any such device...

That said, if the 'fridge in question has it's own LVC, then a direct battery connection probably makes more sense :)

re the Engels, I must confess that I've never taken the time to measure current draw on start-up, but I've always been given to understand that this is not an issue with the swing motor..

In my own case, whenever we're camped for more than a day in the one spot, and the panels are deployed, I do connect the 'fridge(s) the load terminals on the controller (for the afore-mentioned reason), with no known issues..

The beer stays cold, and that's my yardstick ;-)


Catch ya later... Ed C

:)



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