12V solar mat regulators

Submitted: Friday, Mar 30, 2018 at 18:42
ThreadID: 136489 Views:1227 Replies:7 FollowUps:17
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Hi all

This is following on from a previous thread of mine. Ended up going solar, way to go in my mind and is pure logic when you've got a dual battery system under your bonnet (may as well use it!).

Quick question... PWM v MPPT regulators. The controller that has come with my 150W Korr blanket looks quite decent but as I got it quite cheap I'm happy to splurge a little and get an actual regulator and keep the original as spare. I can see from research the MPPT regulators are certainly superior in terms of what they do but what I can't fathom is some of the prices I see. I'm a little put off by some of the cheaper model MPPT's, I'd probably prefer a much more decent PWM regulator for the same price as a cheap MPPT.

Again, after any thoughts on anything/anyone has trialled and tested. As a 150W blanket is certainly more then adequate for what I need (thanks to those that mentioned 12V power consumption tables) I'm not so much being fussy about efficiency, but more or less longevity and reliability. At this stage the Redarc PWM regulators look the goods... a 10amp version will accomodate me just fine.

I've also read somewhere, just out of interest sake, that these solar mats dislike hot surfaces... yet every Joe out there throws them on they're windscreen or bonnet etc. Is this correct? Should they just always be placed on the ground or stood up on wire stands like I've seen some models use.

Regards
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Reply By: Les - PK Ranger - Friday, Mar 30, 2018 at 20:16

Friday, Mar 30, 2018 at 20:16
Theo, I have a couple of Ridge Ryder folding panels from Super Cheap Aust, the 100w and 150w.

The 100w puts out 6amps full sun, the 150w 9amps.
Both come with their own controllers (PWM) and these are 10amp and 15amp respectively.

I would go for at least half again in the capacity to the rated max output, just to be sure.

As far as heat etc, I rarely use either of mine but take them just in case a days rest or delay comes up.
Usually, if we camp early say earlier than 1500hrs, I will bother and hook it up to the 2nd battery directly.
My VSR will stop working shortly after stopping once the main drops to below 12.7v.

Anyway, I like to face the afternoon sun, unfold the panel and place across the windscreen . . . it gives a perfect angle for the remaining daylight, and blocks the sun from the vehicle cabin.
AnswerID: 617932

Follow Up By: Tomdej - Saturday, Mar 31, 2018 at 07:48

Saturday, Mar 31, 2018 at 07:48
I have the same setup, 2 Ridge Ryder solar blankets, 100w and 150w. I made changes to the set up and they changes have made a great improvement to the battery charging.

1. I didn't use the original PWM charge controllers. I am using a higher capacity MPPT controller. I have tested both types of controllers and found the MPPT provides more power to charge the battery. This makes the most difference when the solar blankets (panels) aren't pointed directly at the sun or in low light. This means if you set up the solar and leave your campsite for the day where you cannot be there to keep pointing the solar at the sun the MPPT controller will recharge your battery in less time. This means you need fewer hours of good sunlight to keep your batteries topped up.

2. I placed the MPPT controller next to the battery, and is permanently connected to the battery. This has two advantages. Firstly by having it at the battery and not at the blanket the controller can monitor the battery with much less voltage drop due to cable length and can more effectively charge the battery.. Also instructions for solar blankets (panels) tell you to connect the controller to the battery before connecting the blanket/panel to the controller. Do this out of order and you will not get a proper charge. By having the charger already connected to the battery you cannot get the order of connection wrong.

Happy to further discuss my set up if interested.
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Follow Up By: Les - PK Ranger - Saturday, Mar 31, 2018 at 09:30

Saturday, Mar 31, 2018 at 09:30
They are great bits of info there Tom, thanks.
All noted for future upgrades.

I am slowly but surely setting the Ranger up further for longer stays . . . primarily now I tour daily, but on an upcoming 6 week trip our little group of 4 vehicles will be camping in at places at least 3 or 4 times for an extra night, to enjoy the surrounds.

At the moment my SOC after an approx 15hr camp / overnight is pretty much 83% every morning, so I feel I should be able to get a day in (even with no driving) and not drop by more than 50% . . . recommended not to go below this SOC often, or by a greater amount.
Although I love the 100w smaller package and much less weight, I am probably taking the 150w panel and this should be ok as the usual backup in standard form, as we will be driving short distances those days to local sights, and the alternator tops off the AGM pretty quick, usually only a coupe of hours.

From what I've read, the PWM controllers are not only cheaper, but known the be more reliable, not 100% sure maybe this is changed in recent years.
I know my brothers off grid home setup has blown a few good quality mppt units over some years, but not sure about vehicle setups reliability and how tracks etc affect the workings.

In the next few years when touring at even more relaxed pace, I will set it up like yours, for ease.
At the moment the PWM controller is fine for me as I usually only take either one or the other panel depending on what I think will be needed.

I take it you connect both your panels up and into the MPPT ?
That would have very good capacity increase and make full use of the MPPT benefits.

I hope this is useful info to Theo (the OP) too.

BTW, the Ridge Ryder panels are now $399 (SCA link 100w) and $499 (SCA link 150w) when I checked last night, their usual retail, but you'd be mad not to wait for the sales . . . just checked, overnight they have dropped the usual 20% sales pricing, just for today !!
$319.20 and $399.20 respectively.
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Follow Up By: Tomdej - Saturday, Mar 31, 2018 at 19:19

Saturday, Mar 31, 2018 at 19:19
I have had no reliability problems with MPPT, but I did spend a bit on the controller. Yes, I can connect both solar blankets into the one MPPT controller, and have been experimenting with blocking diodes to ensure a shaded blanket does not bring down the output of the non-shaded blanket. I should be finished testing next month.
I am also experimenting with having the 2 solar blankets facing different parts of the sky for when we are long day walks. Being able to recharge camera batteries, having a good cold fridge, and having plenty of light, and still having a battery at 100% SOC at the end of each day is great, and all without running the car or using a generator....
I have spoken to a number of people who believe they don't need much solar as the battery will keep the fridge running for 3-4 days. Unfortunately they are not looking after their battery. As you stated you do not want to use more than 50% of the capacity. If you do, the number of recharges reduces significantly.
We bought our slide on camper second hand and the battery in it was cooked, mainly due to the badly designed 240v battery charger that kept charging the battery without monitoring it. The charger was an Arlec, and I quickly replaced that with a CTek.
Determining an accurate State of Charge is something else I believe requires investing in. Measuring voltage is not accurate. If you want accurate SOC you need a good quality battery monitor, but again they are not cheap. I can justify mine as it means I know I'm looking after the battery, and I can see if there are any issues with the battery or the system as a whole.
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Reply By: Member - Bigfish - Friday, Mar 30, 2018 at 20:43

Friday, Mar 30, 2018 at 20:43
All solar are less efficient the hotter they get. I never put mine on the windscreen or car bonnet. Lay them on the grass so air can circulate with a couple of sticks to have them pointed to the sun in the best angle you consider.
AnswerID: 617933

Reply By: mike39 - Saturday, Mar 31, 2018 at 08:58

Saturday, Mar 31, 2018 at 08:58
In the case of folding or other double panel units, a method of increasing the charge output of the panel is to disconnect/remove the existing PWM controller and change the panel wiring to series from parallel.
Using a heavier cable, wire or plug in an MPPT controller as close to the battery/s as possible.
I have been using a Victron 75/15 MPPT controller, available for around $105 with a 5 yr. warranty. (75=max input voltage, 15=max output amps) This is a 3 stage controller, bulk, absorption and float
Although often advertised as such, I have yet to see a portable folding panel with other than a PWM controller.
On a 200 w. panel wired as above I see 12-15 amps in full sun
mike
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Follow Up By: Frank P (NSW) - Saturday, Mar 31, 2018 at 14:10

Saturday, Mar 31, 2018 at 14:10
Ignoring cable losses from inadequate cabling and wrongly located controllers, changing to series won't make any difference to the panels output. The panels can only ever deliver their rated wattage, whether connected in series or parallel.

However, you are correct in that a seriesed system can be more tolerant of long cable runs or thin wire between the panels and the regulator and therefore may deliver a better result.

But seriesed panels have drawbacks, the major one being that if one panel in a seriesed pair is shade affected, then the output from whole pair, ie including the fully lit one, is hugely reduced. If they were connected in parallel, only the shaded one is affected and the lit one continues to produce.

Totally agree with your MPPT recommendation, but buyers should be aware of cheap Chinese knock-offs that claim to be MPPT but are not. It's very much a case of you get what you pay for, IMO.
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Follow Up By: Hoyks - Saturday, Mar 31, 2018 at 17:22

Saturday, Mar 31, 2018 at 17:22
I have the cheap one that claims to be MPPT, but isn't.
It does the job and is significantly better than the controller that came on my Aldi panels and would just about boil a battery if you left it alone.

The $30 eBay job is adequate for my needs. I couldn't justify the extra cost of a quality true MPPT controller for a $150 fold out panel that only gets a run a few days a year.
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Reply By: Theo D - Saturday, Mar 31, 2018 at 18:20

Saturday, Mar 31, 2018 at 18:20
The only true difference I'm seeing between the PWM and the MPPT regulator is the better conditioning a MPPT gives. Which I guess in the long run, if you're going away a lot and using this method of charging is probably beneficial to the battery. But, growing up & living in the tropics means that a replacement battery every 5 years is basically mandatory anyway regardless of useage or condition due to abnormal humidity and temperatures. AGM batteries may stand up a little better, maybe a few months more.

The PWM, which from I can see is what pretty well all standard 12V blankets come out with, is really just like a 240V Arlec Battery charger from Woolies, albeit it stops charging when the unit tells itself to stop. It will pump power all day long if given the chance but gives no conditioning or smartness to the battery its helping.

Would having the regulator as close to the battery as possible as many are suggesting make that much of a difference to potential voltage drop? I would imagine it would only be an incidental amount if it wasn't close to the battery. Though with advice given, I'll make sure mine is close to the battery... helps keep the unit out of the direct sun at the worst.

Think going for the slightly more beefed up 15amp regulator compared to the original 10 is probably a safe insurance but the Projecta website details that its important for PWM regulators to be matched accordingly... so perhaps it's more efficient for my 150W blanket to stay with a 10amp regulator as the panels max output is 8.5amp (apples for apples). But swapping to the MPPT regulator may mean better conditioning for the long haul.
AnswerID: 617947

Follow Up By: Frank P (NSW) - Saturday, Mar 31, 2018 at 22:28

Saturday, Mar 31, 2018 at 22:28
Hi Theo,

The "conditioning" or charging quality that the battery sees is not dependent on whether the solar regulator is PWM or MPPT. It the quality of the charger that's built into the regulator.

Basically a solar controller consists of two parts.

The first part, the front end, converts the output from the solar panels into a format the the second part can use.

The second part is simply a battery charger. That can be a simple one or two stage device that, to the battery, might be the same as a piece of crap 240V charger from a department store or eBay that might overcharge or undercharge or otherwise abuse your battery. Equally it can be a sophisticated multi-stage, programmable device that will massage your battery into 100% state of charge in the ideal manner specified by the battery manufacturer.

The front end can be PWM or MPPT. All either of them do is deliver the output from the solar panels in an acceptable form to the charger component. The battery cannot see beyond the charger component. It cannot see whether there is an MPPT or a PWM between the solar panel and the charger and it doesn't care, all it sees is what it is interested in, that is, what the charger is delivering.

PWM devices are cheaper and often have less sophisticated charger stages in an effort to keep the price down. But not all. A notable exception is the Morningstar series, and there are others. They are comparatively expensive.

More often than not the regulator stuck on the back of a budget solar panel or included with a budget solar blanket will be a PWM type of variable quality.

On the other hand, MPPT devices, the real ones, not the cheap Chinese knock-offs, usually have multi stage charger components of varying sophistication. Generally, you will find those on more expensive solar products.

Thus it's not the PWM or MPPT that determines how well the battery is treated, it's the charger component, and GENERALLY, but not always, an MPPT controller will have a better charger, which may have led to your observation.
-------------------------------
Placing the regulator as close as possible to the battery is a matter of physics, not of opinion or suggestion. Depending on the cable size between the battery and the regulator, the distance can make far more than an "incidental" difference. That is why regulators stuck on the back of solar panels with a 10 metre thin cable to the battery are severely compromised or even useless.
---------------------------------
If you panels' max output is 8.5 amp there is no advantage swapping your 10 amp regulator for a 15 amp one unless it is a better quality regulator, either MPPT to replace PWM, or a higher quality PWM with a better charger component.

A "larger" regulator won't get more amps out of the panels. You could put a 50 amp regulator in there - it will work just the same and will give you no advantage.
What could be an advantage with a larger regulator, though, is if you plan on expanding your system in the future.

Also, longevity. Like all things, a component running close to or at its max it will not last as long as one that is loping along at 50% effort. Whether or not a change from a 10 amp regulator to a 15 amp one is worthwhile for 8.5 amps max panel output is debatable.

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Follow Up By: Member - Boobook - Sunday, Apr 01, 2018 at 09:21

Sunday, Apr 01, 2018 at 09:21
Theo, there s much more it that.

A PWM controller will preserve amps and is generally only about 70% efficient. So a 150W solar panel will only give you about 8 -9 amps or about 105W.

A good MPPT controller will preserve power ( watts) is about 95% efficient and will give you about 12 amps and around 140W. It works liek an inverter to give more amps than comes into it from the solar.

A PWM controller wastes the energy as heat.

Tony
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Follow Up By: Frank P (NSW) - Sunday, Apr 01, 2018 at 09:55

Sunday, Apr 01, 2018 at 09:55
Thanks Tony. I was about to edit my post to say something similar but you've saved me the trouble.

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Follow Up By: Les - PK Ranger - Sunday, Apr 01, 2018 at 10:22

Sunday, Apr 01, 2018 at 10:22
This article seems to list most of the pros and cons of both PWM and MPPT . . .
Ererdrive PWM vs MPPT

Not sure why they don't list this as a pro of PWM . . .
"More modern charge controllers use Pulse Width Modulation (PWM) to slowly lower the amount of power applied to the batteries as the batteries get closer and closer to fully charged. This type of controller allows the batteries to be more fully charged with less stress on the battery, extending battery life. It can also keep batteries in a fully charged state (called “float”) indefinitely. PWM is more complex, but does not have any mechanical connections to break."

Also this "MPPT controller forces the Solar array to be comprised of like photovoltaic modules".
Yet @Tomdej in his original reply to mine above (reply#1) says he uses a 100w and 150w folding blanket ok.

I guess it's all horses for courses, for small needs you can go PWM or MPPT, and as your needs grow (especially for myself one day eventually entering the lightweight hard floor camper market) you can move to MPPT and multiple panels as needed.

Can you put different solar arrays into an MPPT system using something like a hub, the basic Ctek d250s for example, or others like that ?
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Follow Up By: Frank P (NSW) - Sunday, Apr 01, 2018 at 11:38

Sunday, Apr 01, 2018 at 11:38
[quote]Not sure why they don't list this as a pro of PWM . . .

"More modern charge controllers use Pulse Width Modulation (PWM) to slowly lower the amount of power applied to the batteries as the batteries get closer and closer to fully charged. This type of controller allows the batteries to be more fully charged with less stress on the battery, extending battery life. It can also keep batteries in a fully charged state (called “float”) indefinitely. PWM is more complex, but does not have any mechanical connections to break.[/quote]

Les,

As a generalisation this is simply not true - see my follow-up to Theo above. Both PWM and MPPT do as quoted. It's not the PWM or the MPPT component that controls that, it's the multi-stage charger component that the PWM or MPPT drives. ANY decent solar regulator will "allow the batteries to be more fully charged with less stress on the battery, " It does not depend on PWM or MPPT.

- "MPPT controller forces the Solar array to be comprised of like photovoltaic modules".

To be at its most efficient, MPPT needs panels of similar Vmp. That is the panel voltage at which maximum power occurs, and that is what an MPPT controller is trying to track. If they are the same, easy as. If they are different there will be a compromise and loss of efficiency. Panels don't have to be the same wattage. I have an array of fixed and portable panels of different brands and wattages but similar Vmp they all work perfectly with my MPPT controller.

- "Can you put different solar arrays into an MPPT system using something like a hub, the basic Ctek d250s for example, or others like that ?"

If I understand your question correctly, yes, up to the maximum total solar wattage specified by the controller manufacturer.


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Reply By: HKB Electronics - Sunday, Apr 01, 2018 at 10:34

Sunday, Apr 01, 2018 at 10:34
I run two PWM controllers and a MPPT controller at times, directly switching form one controller to another results in little difference in current flow using a parallel panel setup I'm sure there are a few others on the forum who would agree.

The 70% efficiency mentioned above a PWM controller is very poor, is that the actual efficiency of the regulator or the supposed calculated power loss due to MPP of the panel? If the controller is only 70% efficient then it is a very poor design, there is no reason a PWM controller can't be as efficient as a MPPT controller.

One thing that doesn't get mention is that for a MPPT to work input voltage needs to be around 2V - 3V higher then the battery voltage, this is not the case with a good quality PWM controller, it will have very little insertion loss which is the main reason I believe there very little difference in performance between the two system when using parallel 12V panels.

The theory and the sales blurbs may indicate MPPT are better but I just don't see any real difference between the two with Parallel panels which most will be using if they have a mixed bag of panels.

As for blocking diodes, I have measured the back flow into several different panels and at 17 volts it has always been less than a 50ma with 12V panels upto 150W, I have never bothered with blocking diodes as the losses across the diode would be higher than the loss due to reverse flow into a panel. There are however some very low voltage drop blocking diodes now available but at around $10 each I still really don't see the value unless you have a panel connected directly to a battery and there's the possibility panel could flatten the battery.
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Reply By: Theo D - Monday, Apr 02, 2018 at 14:54

Monday, Apr 02, 2018 at 14:54
Plenty of reading for me to do here guys, thanks!

Well thats cracker news if the original PWM could only be 70% useful, only making my 150W mat about 105W. I will trial this though next weekend on a 3 night stay near Innot Hot Springs. A MPPT will be arriving in the future, this stuff is interesting me.

My only thoughts for upgrading the 10amp to a 15amp was just a protection if the system spiked and became an open circuit. Certainly no power gain what so ever, just insurance. As suggested I will run the system with the regulator as close as possible to the battery. Will be picking up a pre-made 60cm lead with neg/pos lugs one end & 50amp Anderson on other and have this permanently mounted on bullbar, thus just connecting the regulator to the plug and rolling out the mat. Hey presto.

I have a 2.75kw solar system at home which has been defunct for some time. It worked very well, but the inverter (Samil) seemed to fail at exactly the same time as the warranty expired. Funny how this happens and they wouldn't warrant it. The cost of a new inverter is no where near worth setting the system up again so I'll have a sparky undo the system and I'll rip the panels off the roof. I may even think about running a few of these panels out camping, if its really worth it.
AnswerID: 617998

Follow Up By: Frank P (NSW) - Monday, Apr 02, 2018 at 15:12

Monday, Apr 02, 2018 at 15:12
Theo,

I think your roof panels will be 24 volt, so they will not suit your setup unless you get a regulator that will accept 24Volt (or higher) panels to charge a 12V system. You also need to consider max amps. There are plenty of suitable regulators around.

First thing is find out exactly what the Voc (open circuit voltage) is of your house panels and go from there.

Cheers
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Follow Up By: Bob Y. - Qld - Monday, Apr 02, 2018 at 15:39

Monday, Apr 02, 2018 at 15:39
These are the specs of the house panels we've recently replaced.



I'd suggest you'd need a Victron 100/15, or perhaps an Enerdrive unit, with all the bells and whistles, to complement a house panel or two.

Bob

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Follow Up By: Frank P (NSW) - Monday, Apr 02, 2018 at 15:59

Monday, Apr 02, 2018 at 15:59
They are nominal 24V panels.

Nominal 12V panels have a Voc of about 21 to 22 volts - they are the ones most of us use in a 12V system.

Nominal 24V panels have a Voc of double that - about 42 to 44 volts.

While the controllers you suggest are great products, Bob, you don't NEED to spend that much if your budget is slimmer. For example, this controller will handle three of your panels.

Cheers
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Follow Up By: Member - Boobook - Monday, Apr 02, 2018 at 16:47

Monday, Apr 02, 2018 at 16:47
Theo. Look up MPPT vs PWM on you tube. Lots of people do back to back tests.
PWM is old technology there is no need to use it these days. They waste good energy.
Tony
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Follow Up By: Bob Y. - Qld - Monday, Apr 02, 2018 at 18:10

Monday, Apr 02, 2018 at 18:10
Yeah, I’ve got one of those, Frank, and found it okay.

Think you’ll find the Victron I mentioned is quite a bit cheaper than the Jaycar, by around $100 or so.

Bob

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Follow Up By: Frank P (NSW) - Monday, Apr 02, 2018 at 20:46

Monday, Apr 02, 2018 at 20:46
Mea culpa, Bob. I didn't research the price of your Victron model. Just assumed bells and whistles on a premium brand would command a premium price.

The Jaycar unit is very good value for money.

Cheers
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Follow Up By: Theo D - Monday, Apr 02, 2018 at 20:58

Monday, Apr 02, 2018 at 20:58
Hey Tony

Yea done the youtube thing.

Not blowing smoke up anyones bum here but would honestly take peoples ideas and experiences on here x 100 more than anything on youtube.

Its hard to find good info on the net anymore. People say 'just google it'. You can do that, but you've gotta sift through 98% of rubbish to find the tried and tested info you might be lookong for.

Just my take on it.
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Reply By: mountainman - Monday, Apr 02, 2018 at 17:19

Monday, Apr 02, 2018 at 17:19
I wouldnt be afraid of going the 20amp redarc regulator if its only another $50 or so more.
You possibly might need the extra capacity in the future some time.
What ever you do.
Keep them dry and dont let any water get to them.
Water destroyed my redarc 20amp.
Install inside a sealed box.
Jaycar sell boxes with clear covers that you can see what the regulator is doing.
Drill for the cable entry / exit and seal with silicon
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