what size solar regulator?

Submitted: Thursday, Mar 21, 2013 at 08:56

ThreadID: 101219 Views:1700 Replies:8 FollowUps:3

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BEAR74

Gday all,
I have 2 x 140w panels which will be used camping fishing and hunting around the top end. I need some reliable info on what amp rating solar regulator to get. there is a mppt 20a regulator on ebay which says it can handle 300w which should suffice in my mind but would like some educated opinions on this please?

BEAR

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Reply By: rooster350 - Thursday, Mar 21, 2013 at 10:36

Thursday, Mar 21, 2013 at 10:36

On a good day your panels should each be putting out between 7 to 8 amps , giving you 16 amps..so the 20 amp regulator should be fine...cheers

AnswerID: 507255

Reply By: Ross M - Thursday, Mar 21, 2013 at 12:04

Thursday, Mar 21, 2013 at 12:04

G'day Bear74
I agree with rooster, the total output will be around 16 or 17 amps. If a 20 amp reg is used then it would seem ok but has little reserve to handle that current when in HOT conditions.
The 20amp unit may work well but heat may affect it particularly if the unit is inside a vehicle where little or no cooling is happening and there is no cooling airflow over the unit.
Then the 20amp may not be enough because of the heat dissipation factor.

If you stick with a 20 amp unit I would be fitting a computer fan to the LOAD output of the unit so while the batteries are above the load threshold voltage it will run the fan and cool the unit, thereby ensuring reliability and minimize possible "heat stroke" of the regulator.
Once the smoke gets out of a regulator there isn't much you can do.

Ross M

AnswerID: 507262

Reply By: Member - Boobook - Thursday, Mar 21, 2013 at 12:13

Thursday, Mar 21, 2013 at 12:13

Which MPPT regulator is it? Some are fakes.

280w of Solar is about 17A into the regulator but 23A or more out if you have a low battery.

If you want to get all out of your panels then you will need a MPPT regulator rated at 25A or more.

If the regulator is rated at 20A then it is only 240W unless it is rated 20A in and 25 or more out. This is a warning sign to me that it isn't true MPPT.

Tony

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AnswerID: 507264

Reply By: BEAR74 - Thursday, Mar 21, 2013 at 12:53

Thursday, Mar 21, 2013 at 12:53

http://www.ebay.com.au/itm/20A-12V-24V-MPPT-solar-charge-controller-solar-regulator-15-30-more-power-/200864116548?pt=AU_Solar&hash=item2ec46f2f44
this is the regulator here. cheers for the replies fellas

AnswerID: 507268

Follow Up By: MEMBER - Darian, SA - Thursday, Mar 21, 2013 at 14:14

Thursday, Mar 21, 2013 at 14:14

Caveat Emptor ! 1. The Ebay seller can't even correctly spell the name of the manufacturer (all over their page). 2. The product seems cheaper via the manufacturer. 3. If buying from the manufacturer, you need to wait for 37 days before complaining if undelivered (the Ebay seller ships from China - same outlet ?..... same potential delay ?).
There are a number of Australian based Ebay sellers of such equipment - and you can actually phone some of them prior and discuss your requirements - it appears that low cost, volume selling of commodities on the net doesn't have to involve puzzlement, delays and gross disappointment for the buyer - you just have to find the right supplier :-o).

FollowupID: 784495

Reply By: bluefella - Thursday, Mar 21, 2013 at 17:09

Thursday, Mar 21, 2013 at 17:09

Morningstar pro star 30amp are a very good product not cheap,can find them on ebay in OZZ for about $160-$200.
No affiliation etc.

AnswerID: 507293

Follow Up By: Member - Boobook - Thursday, Mar 21, 2013 at 17:26

Thursday, Mar 21, 2013 at 17:26

These aren't MPPT, effectively wasting about 6 Amps at 280Watts

Tony

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FollowupID: 784509

Reply By: Member - cherrywipe - Thursday, Mar 21, 2013 at 17:17

Thursday, Mar 21, 2013 at 17:17

Hi,
Look up Autoelecs on e bay had 30 amp regs for around $100.
Cheers

AnswerID: 507294

Reply By: Member - Bruce C (NSW) - Saturday, Mar 23, 2013 at 05:30

Saturday, Mar 23, 2013 at 05:30

Hi Bear,

I have several panels but specifically, re your query, I have a 160 watt folding setup and on good days when the battery is down I can get over 10 amps out of the regulator and into the battery. This means in your case, if the panels are mono, that a 20 amp regulator will be borderline with little or no reserve on good days with low batteries.

I would go a 30 amp regulator to be on the safe side. The extra cost at this point is minimal where as if you find you need to upgrade later it is another regulator.

Cheers, Bruce.