MPPT Controller Question...

Submitted: Sunday, Nov 30, 2014 at 12:25
ThreadID: 110295 Views:3758 Replies:11 FollowUps:48
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Thanks in advance for any help.

My question is, Is this normal ?

All my measurements and maths, says I should not have a problem. In fact if I remove the MPPT controller I do not have any probs at all.

I have 120w panel charging a 60AH "Allrounder".
Running Engel in freezer mode, setting 3.
Recharge 2 x 6V and one x 12V Coleman lanterns. (recharged every 2 to 3 days).
Recharge laptop and phone. (phone is used as a modem and is allways fully charged from the laptop USB).
The Engel is turned down to setting 1 at night.

For those interested, the Engel is the biggest user at .95AH per hour...That is point 95. I have measured it many times and always get between .92 and .97AH per hour. I made a blanket using 25mm high density foam. Without the blanket at 25c the Engel uses 1.3AH per hour, with the blanket .95AH. It is that blanket which allows me to get away with a 60AH battery !

That is my usage covered, now my problem. I have two MPPT cons and both give exactly the same results...a flat battery!

If I use the controller, my watt meter shows it delivering .66 amps to the battery. I don't have a hope of keeping the battery charged. If I plug everything in the meter shows what I am using plus .66 amps. So it mostly shows 3.66 amps with every thing running. But if I remove the con and connect the panel direct to the battery, the watt meter shows 5 to 6 amps going in and even with the Engel and laptop running I can see the volts going up in the battery.

The other thing which is odd. If I unplug everything so that just the panel is connected to the battery via either controller (with the watt meter in line) it shows zero when the battery reaches about 12.3 volts. Meaning the controller is stopping all incoming current from the panel if the battery gets to about 12.3V.

As I say, I get exactly the same reading and same flat battery from both controllers. One con (10amp) came with the panel and the other (a 20amp one) I got new. Do I just happen to have two dodgy controllers or is it normal?

To sum up. End of day (when I turn the Engel to setting 1) with controller battery volts will be about 11.2. Without controller volts will be about 13.7.

Thanks again.
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Reply By: Notso - Sunday, Nov 30, 2014 at 12:31

Sunday, Nov 30, 2014 at 12:31
It would certainly appear that there is a problem with both controllers. Is there something in common with the two controllers that would cause this. Is the cable you use to connect the controller faulty? Are all your connections well made?
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Reply By: Frank P (NSW) - Sunday, Nov 30, 2014 at 12:43

Sunday, Nov 30, 2014 at 12:43
Kelpie D,

What brand and model are the controllers? And how much did you pay for them?

Reason I ask is some Chinese cheapies labelled MPPT are not MPPT at all and may introduce problems.

Cheers
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Reply By: pop2jocem - Sunday, Nov 30, 2014 at 13:05

Sunday, Nov 30, 2014 at 13:05
A couple of extra bits of info which may help the more tech savvy give you a better response. I'm not one (;=))
What size and length cables are you using and is the controller mounted close to the panel or the battery?

I have a 30 amp MPPT controller, an 80watt panel and a 100 AH DC battery. The panel I move around to put in the best possible aspect to face the sun. The controller is mounted about 300 mm cable run length from the battery. Can't remember the exact size cable but the copper core is about 6 mm diameter for both the run from the panel to the controller and the controller to the battery.
The only appliance I power from this setup is an older and probably less efficient 39 lt Engel. In full sun the controller shows around 5 amps maximum supplied to charge. The Engel usage with the vehicle in full sun and the fridge on freeze shows around 3 amps being consumed. What all that equates to in amp hours over a time period I wouldn't have a clue. I know that I can run this setup for many days as long as the sun is shining without any other input. From memory I think I have run this lot for about 3 days at the longest. I do turn the fridge down during the night and make sure everything we need out for the next day is done in one lot.

Hope that helps a bit.

Cheers
Pop
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Reply By: The Bantam - Sunday, Nov 30, 2014 at 13:13

Sunday, Nov 30, 2014 at 13:13
Firtsly have you made sure that you are connecting direct to the solar panel and that there is not some other electronics...appart from a diode or two...hiding there somewhere.


NOW.....if a battery is flat or at a low state of charge, there is pretty well no advantage to any regulator..... a conventional regulator would be wide open and a MPPT regulator will be providing no advantge.

It is as the battery begins to charge that a regulator is required.....a conventional regulator simply prevents the battery from being over charged toward the end of the charge cycle.
It may be unfavorable mid charge cycle as the current running into the battery lessens and the panel voltage rises....the panel may be running at 18 volts and the regulator is regulating down to the 13-14 volt range and simply disipating that as heat

A MPPT regulator should behave more or less with no favours in the early part of the charge cycle...because the panel will be loaded and the voltage will be down and the current will be maximum into the battery......it is in the mid to later part of the cyle that a MMPT reg should give the most advantage....tracking the maximum power point, loaging the panel to optimum and delivering optimum voltage and maximum charge current to the battery.

SO you definitely have something going wrong there.

As I say first, make sure you have a direct connection to the panel and that there is not any surplus electronics.

Check all your connections are correct of course

tests the panel and regulator connected only to the battery with no load......remove as many complications as you can.
You will need the battery part discharged to observe the behaviour.

If your regulator is not working, what all your loads are doing will be irrelivent.

Just a thaught.
have you tried to charge this battery on its own on a multistage charger..and tested the battery to make sure it charges and holds charge.

If the battery is buggered the regulators my not want to talk to it.


Of course we need to know what sort of panels you have, you need to check their open circuit voltage and how much current they will deliver into a battery with a low state of charge.

cheers
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Reply By: Rangiephil - Sunday, Nov 30, 2014 at 13:17

Sunday, Nov 30, 2014 at 13:17
I have two x 60 watt folding solar panel.

I have linked them in series , replaced the stock wire with 2x8 Marine B&s x20 metre and then to an Australian produced 10 AMP MPPT controller next to the batteries.

My watt meter registers approx. 6.25 amps in full sunlight when the batteries are below 13 volts and seems to cut to float at about 13.7 volts.

The MPPT samples every five minutes so if you connect it straight up , it takes a while for it to register.

So you should be getting over 6 amps.

It appears there may be something wrong with both your controllers as you should get about 6 amps+ which is PLENTY to run an Engle.
Regards Philip A.
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Follow Up By: Member - John and Val - Monday, Dec 01, 2014 at 07:11

Monday, Dec 01, 2014 at 07:11
Phil,

Did you mean to say that your 2 panels are connected in series? They should be in parallel, NOT in series. The unloaded voltage (ie the feed to the controller, when disconnected from the controller) should be about 22 -24 volts, NOT double that, which it will be if your panels are in series. If in fact they are in series, both your controllers may be (at least) seriously upset and at worst, dead, which could account for what you are experiencing.

Please tell us they are not in series!

John
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Follow Up By: Member - John and Val - Monday, Dec 01, 2014 at 07:32

Monday, Dec 01, 2014 at 07:32
Phil,

My apologies - thought I was talking to the original poster!

Cheers

John
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Follow Up By: Kelpie D - Monday, Dec 01, 2014 at 08:34

Monday, Dec 01, 2014 at 08:34
I am the OP ;)

Not in series.
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Reply By: HKB Electronics - Sunday, Nov 30, 2014 at 14:10

Sunday, Nov 30, 2014 at 14:10
Kelpie D,

Can you please elaborate on the "If I plug everything in the meter shows what I am using plus .66 amps. So it mostly shows 3.66 amps with every thing running." how exactly have you connected everything?

How have you connected the regulator ie which terminals have you connected the solar panel to on the regulator?

What terminals on the regulator are you connecting the battery to?

What terminals on the regulator are you connecting your fridge etc to?

When you connect your watt meter where exactly are you connecting it, ie is the watt meter connected connected to the +VE and -VE battery terminals on the regulator and the output of the watt meter connected to the battery?

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Reply By: Kelpie D - Sunday, Nov 30, 2014 at 15:53

Sunday, Nov 30, 2014 at 15:53
Thanks everyone for the replies.

I wont reply individually for two reasons. 1 I am on solar power and 2, I am in the Wagga area under a tarp fighting off thunder storms.

Pretty much everything mentioned has been looked at. Which leaves me with just the question is it normal. The answer is clearly, no.

The panel is G&P brand. The controller (reg) that came with it is marked as the same brand. The other reg I have is packed away and I don't know the brand of it, but I can get it out after these storms pass.

All those things like cable, connections, loads, plugs etc, etc have all gone through my mind and checked and double checked.

The reg was mounted to the panel. I moved it to the reg. Ando plugs are used for all connections expect battery which has alligator clips with an Ando on the other end. 30cm from reg to battery. 20 amp double plug is on the load side of the reg. In short, all is wired correctly.

To give an idea. We have a sunny patch but I can see another storm coming. The watt meter was reading 4.88 amps with battery at 12.9 volts. I plugged in the reg and I now read 1.66 amps and the volts are dropping as I watch.

I will have to leave there for now...I am about to get hit by a bit of a storm.
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Follow Up By: HKB Electronics - Sunday, Nov 30, 2014 at 16:26

Sunday, Nov 30, 2014 at 16:26
Elaborate on a double plug on the load, the battery needs to be connected to the battery terminals and the load to the load terminals?

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Follow Up By: Kelpie D - Sunday, Nov 30, 2014 at 20:20

Sunday, Nov 30, 2014 at 20:20
Sorry, I had to go for a no show. The storm hit alright, lots of thunder and rain but thankfully no wind. Tail end is a bit breezy. I can see it has just started to leave the other side of Wagga.

Everything is connected correctly. The panel is on the left, solar. The battery is in the middle. The load is on the right. The load is simply one of those 20 amp double plugs...I will take a photo and post it tomorrow.

The battery is new. It is about 6 or 7 months old. Until about 4 weeks ago, it was on a smart charger. I then went to Greens Lake on total solar. The window on the battery changed to white in a few hours and red in less than 48 hours. It was then that I connected the panel direct and it fixed the issue. I thought the controller might be faulty, so tried the 20amp one but got the same result. I then started recording everything and found that both controllers are doing exactly the same.

That is why I ask is it normal.

Sorry, believe it or not, I have to go again

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Follow Up By: HKB Electronics - Sunday, Nov 30, 2014 at 21:53

Sunday, Nov 30, 2014 at 21:53
What is the voltage on the input to the charger from from the solar panel?

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Follow Up By: Kelpie D - Monday, Dec 01, 2014 at 08:56

Monday, Dec 01, 2014 at 08:56
I read 19.7 volts.

This morning the battery volts were 12.2 at 7:10am.

I turned the panel round to face the morning sun, turned the Engel up to 4 and plugged the laptop in to charge. At 7:36am the thermo of the Engel kicked in and the laptop says "plugged in not charging". The battery volts read 13.1

So in 26 minutes of morning sun with no regulator, the panels produced enough to get the Engel back to freeze, recharge the laptop and have enough left over to put .9volts into the battery.

At Greens Lake, I did pretty much the same thing but with the controller in line and the battery went into the red.
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Follow Up By: HKB Electronics - Monday, Dec 01, 2014 at 09:25

Monday, Dec 01, 2014 at 09:25
If your getting 19.7V into the controller, its a 12V controller and all is connected properly and your not getting amps into the battery then I would say your assumption the controller is faulty sounds pretty good.

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Follow Up By: Kelpie D - Monday, Dec 01, 2014 at 09:38

Monday, Dec 01, 2014 at 09:38
Yes, it is 12 / 24 volt auto switching controller. The other one is just 12 volt 20amp.

I cannot post a photo. I need to get an image host first.

I am interested in the below post. I just Googled. It looks like the panels are 14 cell each giving a combined total of 28. If the below is correct, I just don't have enough cells to drive an MPPT.
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Follow Up By: The Bantam - Monday, Dec 01, 2014 at 10:07

Monday, Dec 01, 2014 at 10:07
The first thing I'd be doing is getting rid of those aligator clips.

Its just a point of unreliability.

You need some sort of secure permenent connection to the battery...either proper battery clamps or nuts and bolts with eye terminals on the connecting cables.

cheers
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Follow Up By: Kelpie D - Monday, Dec 01, 2014 at 12:54

Monday, Dec 01, 2014 at 12:54
Yes, I know.

It is a very basic set up. The alligator clips are actually proper battery type, they just happen to come with the panel. I am hoping to get a small camper or pop top maybe next year. Then I will up grade the whole system. But for now it is shoe string budget and basic is best.

Do you know anything about what V8 Trooper is saying? I cannot find anything about it. I have Google blisters on my fingers and cannot find anything about it. If it is correct, it is so far the only answer that would explain why two different controllers give exactly the same measurements and results. Sure they both could be faulty but I think it would be unlikely for them to have the same measurements.
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Follow Up By: HKB Electronics - Monday, Dec 01, 2014 at 15:01

Monday, Dec 01, 2014 at 15:01
Voltage should not be an issue your 19V should be fine, mppt work by increasing or decrease the load on the panel to work out what current it can draw from the panel to get the most watts transferred to the battery.

ie Simplistic explanation, if you think of it as a graph with current drawn as a rising line and voltage as a decreasing line at some point they will cross and that is the maximum power point.

The maximum power transfer might occur at say 16V and 5A, if you connect the panel straight to the battery and it might want to draw 10 amps, the panel voltage would drop dramatically, ie panel output power at maximum power could be 17.8V@6.7A = 120W approx, if we short circuit the panel we may get 7.64V at .1 volts = less than 1 watt. The more load on the panel the less power after you reach a certain point, ie the maximum power point.

The mppt controller will keep increasing the current to the battery (keeping voltage within regulation limits) till the maximum power point is reached, if sun shine decreases then it will decrease the charge current to place the panel in the sweet spot again.

Having a higher voltage panel can become beneficial in that the mppt can use the headroom above the required battery voltage to generate extra current for charging the battery, for example take 19V@5A and convert this to 14.4V@ if the mppt can handle it in that If the battery wants more amps than the

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Follow Up By: HKB Electronics - Monday, Dec 01, 2014 at 15:03

Monday, Dec 01, 2014 at 15:03
Sorry pressed wrong key, should have just been convert this to 14.4V@6.6A. Ignore the rest, being able to edit would be nice.

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Follow Up By: Kelpie D - Monday, Dec 01, 2014 at 16:07

Monday, Dec 01, 2014 at 16:07
Thanks again for the replies.

I still can't get my head around number of cells. If V8 is correct, I will just leave it and run without a reg. But since no one, including panel manufactures and solar experts make mention of it, I am starting to think number of cells is a bit of a garden path.

Anyway. You have made me think. What if I did connect the panels in series. 60 watts @ 24v.. That would give 60 watts with open circuit of 40 volts. I have seen plenty of MPPT sellers and manufactures say they recommend using a 24 volt panel (40 volt). In fact I am pretty sure the 20 amp reg I have recommends a 24v panel.

Maybe, both my regs would prefer a 24 volt panel system. Which in turn would explain why they both give the same results.

I am about to get hit by another thunder storm. So have to go. Yes, Wagga is getting hit again. Not as bad as yesterday but windy this time. I need something better than a tarp. I will be back when this storm passes.

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Follow Up By: HKB Electronics - Monday, Dec 01, 2014 at 16:24

Monday, Dec 01, 2014 at 16:24
I would be surprised if you don't have 36 cells panels, I also don't believe V8 was suggesting you don't use a regulator just that a mppt might not be worth using on a low voltage panel.

You should always use some type of regulator to prevent over charging of the battery.

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Reply By: V8 Troopie - Sunday, Nov 30, 2014 at 20:02

Sunday, Nov 30, 2014 at 20:02
With MPPT its not so much the 'watts' of your solar panels but the number of cells each panel has.
For a 30 cell panel a MPPT is probably a waste of money.
For a 36 cell panel a MPPT gives you a noticeable advantage in charge current.

I use 40 cell semi flexible panels (2 x 120W) and they are brilliant with my MPPT controller.
V8troopie
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Follow Up By: Kelpie D - Monday, Dec 01, 2014 at 09:03

Monday, Dec 01, 2014 at 09:03
That is interesting. In all my research I have not seen this mentioned before.

I am not sure exactly what to look for. If I see it correctly, each panel has 28 cells. 7 down and 4 across. Would that mean it's a 56 cell panel ?
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Reply By: Rangiephil - Wednesday, Dec 03, 2014 at 08:55

Wednesday, Dec 03, 2014 at 08:55
Just to clear up the comment on my post about my panels in series.
My MPPT controller has the ability to run the panels in series as well as parallel, and it is in the operating instructions.
All you have to do is connect the MPPT to the batteryegards first and it detects the required output voltage.
The advantage of the higher voltage is less voltage drop .
It works fine and I get 6.25 amps on a very hot day, with what are cheap 120watt folding panels.
Regards Philip A
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Follow Up By: Rangiephil - Wednesday, Dec 03, 2014 at 09:01

Wednesday, Dec 03, 2014 at 09:01
This is it
http://www.gsl.com.au/mppt12.html
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Reply By: Kelpie D - Wednesday, Dec 03, 2014 at 14:28

Wednesday, Dec 03, 2014 at 14:28
Thanks Philip A.

I might be taking the whole system into a shop to look at. I will ask them to show me exactly what to do.

There is an update to the situation. I now have a 100ah Century deep cycle. But the controllers still do the same thing.

Keeping it brief. The sole reason for having a 60ah Allrounder, is that it's the size battery for the car. I never intended to be on solar for more than a few days upto a week between house sits. The 60 works fine, the figures add up, the math says it can be done. But only if nothing goes wrong ! The plan was to put it in car when I get my little caravan. Then I would have a deep cycle (+ crank battery) as back up if I needed extra power without having the expense and stuff around of dual batteries.

So I went into BCF thinking I really should stop stuffing around and just get a 100AH job. Price way out of my budget. So I said "hey mate what is the best price you can do, here is my club card". He said $169. So I now have a new 100ah.

Today I went to, I think it is called Battery World, in Wagga. I got all new proper fittings. So the alligator clips are gone. I explained in detail what is happening. They to are puzzled as to what could cause the symptoms. They said if can take the whole setup in, they will be happy to check and test it all.
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Reply By: Kelpie D - Thursday, Dec 04, 2014 at 13:38

Thursday, Dec 04, 2014 at 13:38
Don't you hate it when someone states the blatantly obvious and they are probably correct ?

I am in a solar shop and another customer buts in and says "only one thing could explain all the symptoms - a faulty watt meter".

Anyway the question I went in to ask was about changing the panel to 24v. Each person I spoke to in 3 or 4 different shops all said it cannot be done. They all said you cannot charge a 12v battery off a 24v panel. I said the instructions for my controller says they recommend using 24v. I said people on the forum says you can. But they all insist a 24v panel will boil and kill a 12v battery even if an MPPT is used.

My question never got answered because none of them went any further than saying it cannot be done. The question, would the panel still be 120 watt or would changing it to 24v change it to a 60 watt panel ?
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Follow Up By: Frank P (NSW) - Thursday, Dec 04, 2014 at 14:05

Thursday, Dec 04, 2014 at 14:05
Kelpie,

From what I read so far in the thread you have 2 x 60 watt panels in parallel, giving you 120 watts.

If you place them in series you will still have 120 watts but the solar voltage will be doubled and the output current will be halved.

If you have a regulator that says it will accept 24V panels to charge a 12V battery it WILL NOT boil the battery unless it is faulty.

Advantages of seriesed panels:
- fewer cable losses between panels and regulator
- greater likelihood of the solar input to regulator remaining over the threshold MPPT tracking voltage (part of the regulator design), meaning greater likelihood of the MPPT working properly in marginal solar conditions.

Main disadvantage of seriesed panels is that if one of the two gets partially shaded the output from the pair drops drastically. So you will have to keep them BOTH fully in the sun to see the benefit.

Advantages of parallelled panels
- if one panel is affected by shade it doesn't affect other panels

Disadvantages
- Greater cable losses between panels and regulator. You should have reasonably heavy cable if it a long run, eg 10m
- depending on the MPPT threshold voltage of your regulator, in marginal conditions the voltage may drop below that value and stop the regulator from tracking, with a subsequent loss in efficiency.

So by all means hook up your panels in series and see how you go. Your panels' open circuit voltage will about 43 to 44V and when connected to the regulator to a half discharged battery the solar input voltage to the regulator should be about 34 to 36 volts.

If you haven't already got one, an inexpensive multimeter would be a good investment.

Cheers

Frank
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Follow Up By: Frank P (NSW) - Thursday, Dec 04, 2014 at 14:08

Thursday, Dec 04, 2014 at 14:08
Bugger! Hit the wrong button!

"If you place them in series you will still have 120 watts but the solar voltage will be doubled and the output current will be halved. "

Not quite. The open circuit voltage of the pair will be twice the open circuit voltage of one panel (assuming they are twins) and the output current (Isc and Imp) will be as for a single panel.

Still 120 watts total power.

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Follow Up By: Frank P (NSW) - Thursday, Dec 04, 2014 at 14:44

Thursday, Dec 04, 2014 at 14:44
Kelpie,

"But they all insist a 24v panel will boil and kill a 12v battery even if an MPPT is used."

Mate, that is just the biggest load of bull!!

A 24V panel connected directly to a 12V battery will definitely stuff the battery. But through a regulator designed to accept 24V panels and a 12V battery, no way!

Also, mentioning the MPPT threshold voltage got me thinking ...

I wonder if you have a mismatch between your solar panels and your regulator. Some regulators may have a MPPT threshold voltage that is above your panels' maximum power voltage (Vmp). Threshold tracking voltage or minimum tracking voltage may be listed in the specs for your regulator. If it is higher, then putting your panels in series should improve things, as the Vmp from the pair would be double that of a parallel arrangement.

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Follow Up By: Kelpie D - Thursday, Dec 04, 2014 at 15:01

Thursday, Dec 04, 2014 at 15:01
Thanks Frank,

Yes, I will be getting a new multi meter tomorrow. The reason I was relying on the watt meter is because my multi meter got broken by a car driving over it.

I have found a solar forum also saying it can be done.

So pretty much, as long as you have full sun with no shade on either panel, the benefits out weigh the disadvantages.

What about cloud ?

I think you will tell me I am wrong, but here goes. Rounding the numbers just to make it easy. Say the series panels make 40volts at 120 watts amps would be 3. If clouds come over and volts drop to say half that, 20, would I be getting 6 amps? watts / volts = amps.

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Follow Up By: Kelpie D - Thursday, Dec 04, 2014 at 15:40

Thursday, Dec 04, 2014 at 15:40
Thanks again Frank,

Seems you posted while I was typing :)

Yeah, a load of bull. Maybe they just say that in the hope I will buy a new bigger panel.

I will give it a go. I got the 20 reg out and it also says 12/24v. So tomorrow I will get a new multi meter to confirm whether or not the watt meter is faulty. With a proper working meter on hand to measure everything, I will series connect the panels and see what happens.

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Follow Up By: Frank P (NSW) - Thursday, Dec 04, 2014 at 16:35

Thursday, Dec 04, 2014 at 16:35
Kelpie,

There are some crap MPPT regulators out there. Some are not proper MPPT at all.

So providing you don't have one of those, and instead have a good, functioning one you will get the best from your panels in all conditions until the panel voltage drops below the regulator's minimum tracking voltage.

Panels work on light intensity, mostly visible light. So it can be cloudy but still enough light to generate useable output. What happens in cloudy conditions is that it's not the voltage that drops, it's the ability to produce power. Power is the product of volts times amps.

Simplistically the MPPT reg will adjust the load it applies to the panels to keep the product of volts time amps at a maximum. Some, particularly the more sophisticated ones, are better at it than others.

In monocrystalline panels the Vmp (maximum power voltage) is typically about 3/4 the open circuit voltage (Voc), but that's an approximation - it can vary with brand and prevailing conditions.

The simplest budget systems assume that rule. They test the Voc and then load the panels to hold the voltage at about 3/4 of the Voc. The power produced is then fed to a circuit that changes it from 40 volts at 3 amps (using your figures) to, say, 12 volts at 10 amps at the battery.

What happens then is further complicated by the multi-stage charging algorithm usually built into these regulators, but let's just stick to the solar part for the moment.

When a cloud comes the regulator would adjust the load on the panels so that the volts stayed at 40. Because of the reduced light, fewer amps can be produced, say 1.5. So power produced is 1.5 amps times 40 volts, = 60 watts. That is then converted to, say 12V and 5 amps at the battery.

There are more sophisticated methods in more advanced controllers, where the controller tries a series of voltage/current combinations until it finds one that gives the maximum product. There are a number of ways of doing this, no need to discuss them here, but the advantage of those is that they get the absolute best out of the panels in the prevailing conditions.

You won't always get the stated wattage out of your panels. The stated wattage is at a standard set of conditions which don't happen much in real life. Cell temperature in particular affects the output of panels, and being dark in colour they do get hot in the sun. After all losses and factors are accounted for, you will be doing ok to get, on average, about 70% of your stated 120 watts as useable output. So your sunny 40 volts and 3 amps could be 40 volts and 2.1 amps and your cloudy 1.5 amps could be only 1.05. But on a good day - cold clear bright sunshine on a mountain top :-) - you could get 100% and maybe more.

Cheers
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Follow Up By: Kelpie D - Thursday, Dec 04, 2014 at 17:24

Thursday, Dec 04, 2014 at 17:24
Thanks again Frank for taking the time.

This is the 20amp reg I have - http://www.waohe.com/html_products/Solar-Charge-Controller-51.html

I haven't found my 10amp one on line. But I will try the 10 first.

Even if my watt meter is faulty and showing lower values, trying 24 volt sounds like a good idea. On a really good day I can get 5amps. But if a cloud comes over I am lucky to read 1.5 amps. (Oh, it is a mono panel.) According to my watt meter.

I understand the figures are all just best guess. But they are sounding pretty good to me.

No wonder the shops say it cannot be done. Five minutes, a couple of screws and a bit of wire and you have your panels in series and doubled or maybe trebled your charging ability. Or you could pay maybe $700 or $1,000 to upgrade and get the same result.
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Follow Up By: Frank P (NSW) - Thursday, Dec 04, 2014 at 17:31

Thursday, Dec 04, 2014 at 17:31
"The simplest budget systems assume that rule. They test the Voc and then load the panels to hold the voltage at about 3/4 of the Voc."

Actually, there are some even simpler ones which I think are an absolute cheat and not MPPT at all because they don't track anything, they just make assumptions.

They assume a 12V panel. They don't test for Voc. They assume a Vmp of about 17.5 volts (or whatever) and hold the panel at that voltage. What happens after that in terms of charging parameters is somewhat doubtful.

God knows what this one does, but anine dollar MPPT 20A regulator?

I don't think so.
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Follow Up By: Frank P (NSW) - Thursday, Dec 04, 2014 at 17:50

Thursday, Dec 04, 2014 at 17:50
Kelpie

Our follow-ups crossed in the ether and it's a bit embarassing because the $9 item I rubbished I found independently, before you posted your wahoe link.

Mate, I think you have a dud. I think it was a dud when it left the factory. And I think they knew it was a dud when they sold it to you. I think you need to find a decent unit and unfortunately that is going to cost a bit more than $9 on eBay.

I don't know what your budget is. A good non-MPPT is way better than a crappy rip-off and need not be too expensive - sub $100. Members of my club have had good results with Powertech brand, both non MPPT (=PWM) and MPPT. Available from Jaycar and, probably cheaper, eBay.

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Follow Up By: Kelpie D - Thursday, Dec 04, 2014 at 19:23

Thursday, Dec 04, 2014 at 19:23
$9 ?

I got ripped off. I bought it maybe 2 or 3 years ago and paid, I think $20. I used it on a 20 watt system for about 18 months and never had a problem. I have it connected now to this system and have no idea what it is doing because I have removed the watt meter. But It is holding 2 lights and the battery window is green.

One of the shops today tried to sell me a basic non-MPPT Powertech at $50.

There is a Jaycar in Wagga. The budget is "save ya money to get a van". I was going to get a new multi meter, but I will take your advice and get a Powertech controller instead.

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Follow Up By: Frank P (NSW) - Thursday, Dec 04, 2014 at 21:02

Thursday, Dec 04, 2014 at 21:02
Kelpie,

I have one of these sitting in my garage. I don't need it any more.

You can have it for the cost of postage.

But before I send it I want to test it. So if you can hang on a bit I'll let you know if it's a goer.

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Follow Up By: Kelpie D - Thursday, Dec 04, 2014 at 21:26

Thursday, Dec 04, 2014 at 21:26
Well, I was not expecting that. Thank you very much.

I am on a caravan park until the 20th. I will ask them tomorrow if I can use their post address. Otherwise, my next house sit starts on the 23rd near Nowra and I will be there until the end of Feb.
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Follow Up By: Frank P (NSW) - Thursday, Dec 04, 2014 at 21:40

Thursday, Dec 04, 2014 at 21:40
OK Kelpie.

Send me an email to frankp79 at hotmail dot com

This is an invitation only email address so any emails that I haven't asked for are dumped.

I don't know if I can do before the the 23rd, but I'll try.

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Follow Up By: Kelpie D - Thursday, Dec 04, 2014 at 22:09

Thursday, Dec 04, 2014 at 22:09
pink bubble gum it's done
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Follow Up By: oldtrack123 - Friday, Dec 05, 2014 at 12:18

Friday, Dec 05, 2014 at 12:18
QuoteKelpie D posted:
That is interesting. In all my research I have not seen this mentioned before.

I am not sure exactly what to look for. If I see it correctly, each panel has 28 cells. 7 down and 4 across. Would that mean it's a 56 cell panel }

Hi
There is your problem, they are cheap grid panels
They are not suitable for battery charging in parallel
The load voltage will be too low
If you are confident that the MPPT reg is suitable for a series connection of the panels[can accomodate at least up to 40V],that will solve your problem

PeterQ
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Follow Up By: oldtrack123 - Friday, Dec 05, 2014 at 12:30

Friday, Dec 05, 2014 at 12:30
Hi Kelpie
In addition,I doubt that anything is wrong with either Reg ,or your meter
But the PWM reg will not be suitable for the panels in series

Fit that MPPT reg as close to the battery as is practical.
note: the panels combined output will still be 120W,but the current into the reg will only be around 4Amax
The output into the load ,in good conditions should be around 8A

PeterQ
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Follow Up By: Frank P (NSW) - Friday, Dec 05, 2014 at 14:22

Friday, Dec 05, 2014 at 14:22
Kelpie,

Before you go ahead with my offer, I think you should check out oldtrack's suggestion.

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Follow Up By: Kelpie D - Friday, Dec 05, 2014 at 14:34

Friday, Dec 05, 2014 at 14:34
Thanks oldtrack123,

Actually what I don't know to look for is whether a cell is the square thing with corners at 45 degrees or if they are half that. My panels have a row of half squares across the bottom.

The panels are working just nicely.

I got a new multi meter today. It confirmed that the watt meter is in fact faulty. The watt meter told me the battery was 13.4 volts and the multimeter said 12.4. I tend to go with the multi meter because the window is white. The watt meter was saying 3.66 amps at 14.5 volts was going into the battery and at the same time I was reading 5.5 volts on the multimeter.

So, back to Jaycar. I got a cheapy PWM controller. It has been connected now for about 2 hours. Battery volts are 13.2 with nothing connected. I have not bothered to see what the watt meter would say.

So in short, In turns out it was a faulty watt meter giving me wrong figures. That made the math say I was doing OK, when in fact I was going down hill at a great rate of knots.
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Follow Up By: Kelpie D - Friday, Dec 05, 2014 at 14:43

Friday, Dec 05, 2014 at 14:43
Thanks Frank,

I just replied to your email. I will reply to your first email shortly, have to take the kelpie for a walk first.

I would like to take your offer. I understand the 24 volt issue you mention in your email. It was also very good of you to go out of your way to get it tested. Good of Jaycar to help out too. The postage you stated will not do though, you would have spent more than $8 on petrol and time. I think a six pack is about $16 these days, so lets make it $24.
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Follow Up By: Frank P (NSW) - Saturday, Dec 06, 2014 at 18:24

Saturday, Dec 06, 2014 at 18:24
Thank you, mate. More than generous and gladly accepted.

Cheers!
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Follow Up By: Frank P (NSW) - Saturday, Dec 06, 2014 at 21:52

Saturday, Dec 06, 2014 at 21:52
Kelpie cannot post pics at the moment, buut he has emailed a couple to me.

Here's the label on the back of one of his panels


I did a bit of googling and found two versions of he GPM-2F-120W panels, one 28 cells, the other 36:

and


It's a bit confusing having the same model number for quite different panels, but I guess that's the Chinese way.

That aside, we can be assured that he has 28 cell panels. The Voc is 17.5V, Vmp is 14V.

I believe these will work in series into an MPPT regulator.

Will they work in in parallel into a PWM regulator?

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Follow Up By: oldtrack123 - Saturday, Dec 06, 2014 at 22:20

Saturday, Dec 06, 2014 at 22:20
HI
That confirms thet are not battery charging panels .AS per my suspicion
12v Battery charging panels have an OC of around 21V
& MPP around 17V
The only way they will do the job of fully charging a battery is series connected with A MPPT reg that can take 40V .


PeterQ
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Follow Up By: oldtrack123 - Saturday, Dec 06, 2014 at 22:29

Saturday, Dec 06, 2014 at 22:29
Hi Frank
They will not fully charge the batterry as a parallell set
They may, if the battery is not too flat to start with
[low open circuit voltage'] but can put in a small charge & supply a connected load
I think that is what Keplie is seeing NOW but the voltage @Pmax is too low
It ned to be nearer 16<17V
Many regulators have problems starting up if the battery is TOO flat
Require a certain battery voltage to start operating.


PeterQ
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Follow Up By: Frank P (NSW) - Saturday, Dec 06, 2014 at 22:30

Saturday, Dec 06, 2014 at 22:30
Hi PeterQ,

I presume that with a PWM solar controller (or even without one), in parallel they would charge a battery to close on 14.0V. Not a full charge, as you say, but a charge nonetheless. Would that be correct?

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Follow Up By: Frank P (NSW) - Saturday, Dec 06, 2014 at 22:32

Saturday, Dec 06, 2014 at 22:32
Thanks Peter. Follow-ups crossed in the ether. You beat me by a whisker :-)

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Follow Up By: Frank P (NSW) - Saturday, Dec 06, 2014 at 22:49

Saturday, Dec 06, 2014 at 22:49
Peter,

Based on your Follow-up 23 above...

If Kelpie had a different PWM reg like the one I'm offering him, if he had the fridge on the load output and the fridge was running, would he get anything into the battery?

I'm thinking now that though the panel might run the fridge, the fridge load may pull the volts down too much.

The specs for the reg say the PV to battery differential is 0.8V and the PV to load differential is 0.4V.

Manual below if you're interested.

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Follow Up By: Kelpie D - Sunday, Dec 07, 2014 at 09:02

Sunday, Dec 07, 2014 at 09:02
Thanks Frank and Peter,

Before I purchased the panels, I did do some research. I recall findind a set of figures that matched very closely to more expensive brand panels. The second chart posted by Frank looks like it.

To be honest, I have not taken any further notice of the specs until now. It now seems that I got the one shown on the first chart above.

Just out of interest, I might give the series a go just to see what happens. I have more or less given up on both the MPPT regs I have. What is the worst thing that can happen if the series connection causes probs? I assume it will just burn out the reg? If that is the case I will try it.
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Follow Up By: Frank P (NSW) - Sunday, Dec 07, 2014 at 09:37

Sunday, Dec 07, 2014 at 09:37
Kelpie,

You said earlier in this thread that the documentation for at least one of your MPPT controllers said it was 12/24 volt. Did it say what the max Voc or PV voltage allowed is? For 24V panels it should be around 42V or more.

If there is any doubt, then there is a risk of damage.

Being cheap regulators they may not have much protection. If you're prepared to accept the risk of damage to them this is what I'd do:

Wait until you have a lengthy period of consistent sun, then
- hook up your panels in series; do not connect them to a controller yet
- place your watt meter in the output between the controller and the battery and connect to the battery.
- observe the wattmeter and write down what it says
- connect the solar. Check for leaking smoke :-)
- observe the wattmeter and write down what it says

Do that for both MPPT regulators

Tell us what the results are.

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Follow Up By: Kelpie D - Sunday, Dec 07, 2014 at 12:44

Sunday, Dec 07, 2014 at 12:44
Thanks Frank

It is not really very sunny today. I might follow your suggestion some other day.

The panel is now in series. I connected the 20amp $9 job. No smoke yet.

The Good...It is working. Battery volts have gone from 12.99 to 13.6 in about 15 minutes. All three lights are on on the controller for the first time. The watt meter is in line on the solar side. The multi meter confirms the watt meter readings - they are the same.

The Odd...I read 31 volts open direct at the panel terminals. Connected to the controller I read 13.1. The multi meter confirms 13.1 volts at the panel terminals when connected.

Confirming amps with the multi meter is a hassle with ando plugs, but the watt meter said 6 amps at 13.1 volts.

It has been about 30 minutes now. All still looks good. The 3rd controller light is now going off and on, indicating the battery has gone to float. Battery volts at the terminals is now 13.7. The watt meter says amps have dropped to 1.8.

BTW. All these measures are with no load. I have the Engle running off the Allrounder in the car whilst I am doing this.
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Follow Up By: Kelpie D - Sunday, Dec 07, 2014 at 13:01

Sunday, Dec 07, 2014 at 13:01
Minor up date to the above.

It is not in float.

Just had some full sun. Amps jumped to 4.5 and the third light is on and steady. It looks like it is in bulk.

Still no smoke and looking good.

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Follow Up By: oldtrack123 - Monday, Dec 08, 2014 at 13:46

Monday, Dec 08, 2014 at 13:46
Kelpie D posted:

The Odd..

[1].I read 31 volts open direct at the panel terminals.

[2] Connected to the controller I read 13.1. The multi meter confirms 13.1 volts at the panel terminals when connected.

[3]Confirming amps with the multi meter is a hassle with ando plugs, but the watt meter said 6 amps at 13.1 volts.

It has been about 30 minutes now. All still looks good. The 3rd controller light is now going off and on, indicating the battery has gone to float. Battery volts at the terminals is now 13.7. The watt meter says amps have dropped to 1.8.

BTW. All these measures are with no load. I have the Engle running off the Allrounder in the car whilst I am doing this.


Hi
Perhaps you will not read it BUT,
[1] With those panels in series , with a MPPT controller, that is near enough to what one could expect
[2] I assume that reading is with the battery connected? & at the reg's battery terminals
You would be reading BATTERY voltage

[3] that is only 78W , but will be dependent on sunlight
The Max you could expect facing the panels direct into BRIGHT sun with a low soc battery would be around 18A


PeterQ
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