Which type of solar regulator?

Submitted: Monday, Apr 25, 2011 at 11:38

ThreadID: 85853 Views:7843 Replies:4 FollowUps:11

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This article covers every aspect of solar and its design and installation in RVs (camper trailers, caravans and motor homes). It shows how much power solar panels really produce,

Member - Keith C (NSW)

Hello all, I am putting together a folding solar set-up for camping, the panels will be
120w Suntech, I am not sure about the size and type of reg to use, and where to install it. Is the MPPT better than the standard type sold with most solar setups, It will be charging 2 agm batteries, one is 90a/h the other 130a/h linked together in the car, so in all 220a/h,they run a 40ltr Engel on a low setting plus an 18ltr waeco used as a freezer,set just at the lowest freeze setting. This setup works for me now, charged by running the engine once in a while, but I would like to use solar, most of our camps are in open country usually with plenty of sun. Can anyone offer advice please. Regards Keith

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Reply By: Member - Frank P (NSW) - Monday, Apr 25, 2011 at 14:25

Monday, Apr 25, 2011 at 14:25

G'day Keith,

MPPT regulators can be around 20% more efficient better than the standard type and now there's one that's very reasonably priced, and it's Aussie made. Have a look at GSL Electronics. Their MPPT regulators were written up in the april edition of Overlander.

Their smallest ones, MPPT 12-1 (RRP $130 +GST) and 12-2 (RRP $180 +GST) should do the trick. Their tech data says that the minimum solar voltage for MPPT has to be 15.5V. I found that I had to rig my panels in series to get effective MPPT. That means you need bypass diodes in your panels (mine had them in the junction box already, maybe yours will too). You'll also need a blocking diode to stop reverse current when there's no panel output.

I've had ecellent results with their 30 amp model.

Cheers

Frank

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Follow Up By: Peter McG (Member, Melbourne) - Monday, Apr 25, 2011 at 14:53

Monday, Apr 25, 2011 at 14:53

Keith

Check Ebay. You should get a Wellsee 15amp MPPT regulator for around $70. I use this on my 120watt folding set. Works fine.

Peter

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Follow Up By: Member - Frank P (NSW) - Monday, Apr 25, 2011 at 15:54

Monday, Apr 25, 2011 at 15:54

Keith,

On re-reading your post I'm not sure if you're using 2 x 60 watt panels for 120 watt total or 2 x 120 watt panels for 240 watts total. For 240 watts, if you are interested in the GSL product, you will need the MPPT 30.

Frank

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Reply By: paulnsw - Monday, Apr 25, 2011 at 15:00

Monday, Apr 25, 2011 at 15:00

If you can afford the best use the best Morningstar Prostar 30A with meters Has LCD meter for battery voltage, solar amps in and load amps. Mount the regulator somwhere convenient you can see the meter and reasonably close to the battery and use correct size cable.

Having tested the GSL (made in China) they are better left on the store shelf for somebody else to buy.

Unfortunately some people are hyping up MPPT to be made to look far more than it is. MPPT to get the full benefit requires specific conditions. Cheap MPPT are that cheap and nasty and many not as good as a quality PWM solar regulator.

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Follow Up By: Member - Kevin S (QLD) - Monday, Apr 25, 2011 at 15:39

Monday, Apr 25, 2011 at 15:39

I have read somewhere recently that field tests have shown MPPT regulators to be superior in cooler climates but not of much benefit when solar panels become really hot. Does anyone know anything about this?

Kevin
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Follow Up By: Nomadic Navara - Monday, Apr 25, 2011 at 18:10

Monday, Apr 25, 2011 at 18:10

There was a report that an MPPT controller would produce over 30% extra current from a panel. When the author was pinned down and produced his results it was found that the figures were recorded in Arctic conditions where the panel was only producing a fraction of its rated output. Similar reports have shown increases of over 20%. However these were experimental results in produced in conditions favourable to good results and not average operating conditions.

Those results are still being touted as what the average punter will get with his MPPT. If you can average 15% improvement with a very efficient controller you are doing well. You can produce better results with 20% more panel capacity for less total cost.

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Follow Up By: Member - Boobook - Tuesday, Apr 26, 2011 at 08:08

Tuesday, Apr 26, 2011 at 08:08

Peter, what you are saying is not correct.

Have you trried a MPPT controller????

I have never taken my camper and solar set up to the Artic but I regularly see 25% plus improvement over the PWM current. I have ammeters and volt meters on both sides of the reg.

I would say that i get an average of at least 20% improvement over my old system. As a retired Electronics engineer I do have some insight as to the workings too.

There is at least one decent MPPT panel available for about $100 that is very good. I would never buy a (Wellsee one on ebay againa though, it is not true MPPT).

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Follow Up By: Member - Kevin S (QLD) - Tuesday, Apr 26, 2011 at 09:47

Tuesday, Apr 26, 2011 at 09:47

The comments to which I referred were, from memory, not of tests carried out in the Arctic but under the harsh sun of a northern Australian summer. The conclusion reached was that an MPPT controller was of little benefit under such conditions but was more effective in cooler conditions where the panels did not get so hot.

Perhaps if Boobook had informed us where he is using his controller then we can consider his comments in proper context. What I am looking for is confirmation or otherwise of the claim that I had read. I wish I could find it again, but there you go!

Kevin
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Follow Up By: Member - Frank P (NSW) - Tuesday, Apr 26, 2011 at 10:26

Tuesday, Apr 26, 2011 at 10:26

I did some tests in SW Sydney a few days ago in clear sunshine. 4 x 60watt panels set up in series/parallel.

Each pair of panels has an open circuit voltage of 44V. The pairs are connected in parallel to the MPPT controller. The output from the controller was 16.8 amps at 12.9 volts = 216 watts.

Measured solar volts was 32V, solar current was 7A, = 224watts of solar from 240 watt panels.

If solar controller efficiency is calculated as (output watts divided by solar watts) x 100, then the above figures represent about 96%, which is in line with MPPT manufacturer's claim.

Frank

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Follow Up By: Member - Boobook - Wednesday, Apr 27, 2011 at 08:14

Wednesday, Apr 27, 2011 at 08:14

Kevin I have regularly tested it in Melbourne where I live asl well as observing a big improvement generally. I monitor the output when I travel witht he camper, which includes a lot of Victoria, Tassie, Broken Hill, Flinders Rangers, SE NSW, To The Gulf and Back...

It works as described just about anywhere, though it is true that that the improvement is greatest when the panel is colder and outputting a higher voltage, and the batteries are lower, This is best observed in the morning when a full 30% improvement is the norm.

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Follow Up By: Member - Boobook - Wednesday, Apr 27, 2011 at 11:01

Wednesday, Apr 27, 2011 at 11:01

I forgot to mention, unlike most of the ebay MPPTY regulators, this one IS a a true MPPT with true power conversion.

Real MPPT

You can also get a great display showing voltage, current, power and charge in % and AH for the battery and panel from the same supplier for abotu $30.

This is a great little unit, nearly as good as my $700 Outback MX60.

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Follow Up By: brett - Wednesday, Apr 27, 2011 at 13:18

Wednesday, Apr 27, 2011 at 13:18

I just purchased the GSL 12A MPPT reg off the internet for under $100 delivered and it works perfectly. While it doesn't say where it's made GSL are a Sydney company who made all there stuff here but like everything some of their stuff is made in China now unfortunately and the MPPT12 is probably one of them. But the quality is excellent. I have 5 20W panels to give me 100W and used to get around 7 Amps out of them. I now get 8 Amps with the GSL so thats 1 Amp free, why would you knock back free power. The gain is very easy to demonstrate, measure current going into reg, then measure thecurrent going into the battery. These were in temps of around 25deg in full sun.

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Reply By: BrigalowO - Monday, Apr 25, 2011 at 17:57

Monday, Apr 25, 2011 at 17:57

Personally, I would never have two 12volt batteries linked, especially two different sized ones. If one fails, both are damaged. I also believe that you will be significantly undersized with solar for what you want to achieve, particularly with one as a freezer, even an 18litre one.

To maximize your solar charging regime, buy a Morningstar Sunsaver Duo regulator which as the name indicates, provides the dual facility to split the charge to each battery 50/50 or 90/10. These are the Rolls Royce of solar regulators.

Ideally, you should have more solar capacity, and one battery per fridge. It is a simple solution to avoiding parrallel batteries being dragged down by one faulty one.

Robert

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Follow Up By: paulnsw - Monday, Apr 25, 2011 at 19:20

Monday, Apr 25, 2011 at 19:20

The 18l freezer will use as much power as his 40l fridge.
240w solar would be needed to meet power requirements.
They dont know their power needs and how do the job properly and won't or can't spend the money to do the job correctly. The amateur arm chair experts here always know better and cannot be told. I concur with your post.

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Reply By: Member - Steve M1 - Tuesday, Apr 26, 2011 at 14:46

Tuesday, Apr 26, 2011 at 14:46

Hello all, Alot of gizmo talk ? I like the 'KISS' method. = Keep It Simple Stupid.
I have 2, 130A/H Trojan deep cycle batteries in back of ute charged by 85W solar panel, also charged by vehicle when driving, utilizing a 'Morning Star Sunsaver' - 6 SSR-6-12V. Solar in: 6.5 A, Load: 10.0 A.
This powers: Engel in ute (for cold beer ); A 1000W Inverter for caravan, charging computer; 3 in 1 fridge in caravan, 12V or 240V lights, and of course the meat/vege fridge in caravan. If sun shine not avail. Gas & generator.
Good luck Keith C (NSW )
Regards Steve.

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