Can I use this panel on a Motorhome or caravan , came off my son in laws roof. If so what reg would be needed for 2 of them.

Cheers

Mick

Product Description

This is all I could find when I Googled it , only 175 w not 185 w

Hi Mick

Yes you can use that panel(s). If you have a 12V battery setup then you will need to use a MPPT regulator to output suitable voltage for them. Be careful to note the ratings are suitable for the total watts of the panels.  If you have a 24V system them any type of regulator would work but a MPPT one will be better.

These are largish panels and do need to be well supported along their length. In fact I would put a soft support under the center to help the glass panel a bit on the rough bumps.

Note also that the cheap MPPT regulators are fakes and do not really work properly as MPPT but may work as a simple regulator. The cheapest brand that I know works OK is Tracer, which are available in all the usual places at a good price. You could google for more information, or search for information on this forum with the "search" function in the blue strip up the top. It has been discussed here not long ago.

Cheers Jaahn   

goldcoaster wrote:

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Thanks Jaahn,
It will be a 12v system. So how do I calculate the size of mppt to the amount of watts.
Cheers
Mick

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 Hi Mick

Just look at the specs for the different units and use the max watts for your panels.

Because the MPPT controller takes higher voltage from the panels and converts it to lower voltage for the batteries, the battery current is increased proportionally, so you must be careful. But the maximum wattage of the panels always remains the same.

Here are some specs taken from an Ebay add;

 Item  Model                       1210                           2210                          3210                          4210       

So you have 2x 185 W = 370 Watts max panel power.

so model 3210 should be OK at 12V nominal battery voltage.

Search for Tracer solar controller and look at the units available. There are several model available now. You can also get a remote meter to fit to it so you can see what is happening to your system when the controller is hidden down near the battery.

  Cheers Jaahn

PS If the panels are flat mounted on the roof then the wattage can be a "bit"over as the panel output is always lower and the controller would self-limit the current in the unlikely event of it ever being too high. 

kezngaz wrote:

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Would the controller have to be able to accept 36.2 v
Or 45.3v, just for furure reference?
Thanks.
Kezngaz.

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 Hi Kezngaz

The controller must be able to accept at least the Maximum panel voltage. But better ones and MPPT good controllers are usually rated at much higher voltages.

EG From the same Tracer unit the specs are 100V. So you can even use the panels in series. Which may have some advantages, perhaps ? However not to my liking with these 24V type panels on a mobile home/caravan roof. 90 volts DC is too high for me !  

Max VOC ---- 100V

Cheers Jaahn

goldcoaster wrote:

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Jaahn ,
If I read your post right , you wouldn't use these panels. As I got these panels free , 6 of them , should I put them on my house instead of motorhome and buy other panels . My last motorhome had 450w supplying 3 x 120ah Batteries , never had a problem running out of power , fridge/freezer 190ltr 12v/240 , 60ltr Engle, lights, TV's and other things so I would like the same in the new motorhome.
Cheers
Mick

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 Mick,

I see that I should not have said more than the basic answer ??

YES use those panels. You said you wanted two, that is 370 watts. Wire them in parallel into, say a Tracer 3210 and all will be well. That setup will work well for you IMHO. If you wanted to use more panels, put them  in parallel, but you will need a bigger rating controller to match the watts at 12V.

_____________________________________________________________________________________________________________________________________________

          Kezngaz wrote

          Sorry jaahn.
          Given the example above, which reading is the one your on about?
          Kezngaz

________________________________________

Kezngaz,

The reading you asked about is the OCV, the Open Circuit Voltage, 45.3V for this panel. That is the highest voltage that the panel can reach when it is in full sun and not producing current. So a controller must be able to take that voltage so it does not burn out. The Tracer in my example will take up to 100 volts so it is quite safe to use.

Jaahn

Aus-Kiwi wrote:

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What if you had two or three batteries charge them in 24 or 36v . But feed off 12v .off EACH Battary ??

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 Aus-Kiwi,

It is consider very bad practice to use a string of batteries for charging but use the individual batteries  seperately for 12v power. It will lead to unbalance in the batteries and they will start to charge to full at different times. The charger will not be able to sense this, so it is a short cut to a stuffed battery. It is hard to say whether the over charged one will fail before the under charged one 

Do not go there is the simple answer. If you have 24V truck then convert the system to 24V house or fit a 24-12v converter. Probably worth less than the first battery to fail.

Jaahn

Jaahn wrote:

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Aus-Kiwi wrote:

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What if you had two or three batteries charge them in 24 or 36v . But feed off 12v .off EACH Battary ??

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 Aus-Kiwi,

It is consider very bad practice to use a string of batteries for charging but use the individual batteries  seperately for 12v power. It will lead to unbalance in the batteries and they will start to charge to full at different times. The charger will not be able to sense this, so it is a short cut to a stuffed battery. It is hard to say whether the over charged one will fail before the under charged one 

Do not go there is the simple answer. If you have 24V truck then convert the system to 24V house or fit a 24-12v converter. Probably worth less than the first battery to fail.

Jaahn

-- Edited by Jaahn on Monday 10th of July 2017 09:25:59 AM

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A BIG DITTO

goldcoaster wrote:

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Thanks again Jaahn.

Can I pick your brains a bit more.

Parallel is pos to pos , neg to neg . I hope I got that right.

Once the panels are joined in parallel , does the wire down to the MPPT need to be heavy duty. Recommendations on size .

Cheers
Mick

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Hi Mick 

Yes parallel is as you say  pos to pos , neg to neg panel connections.

The wire down to the regulator needs to be a good big size so little power is lost. Say 10AWG would be OK and good clamp connectors where you joint the panels to it not rubbish. Bigger is OK. Note there is confusion about wire sizes so do your home work when you buy to ensure you get what you asked for.

The wire from the regulator to the battery needs to be twice as thick copper. Say 6 AWG if short. Bigger is OK.

Jaahn

Sorry Bagmaker but your talking to a novice . If it's the black box on the back of the panels , I haven't opened it up.  Wouldn't know what I was looking for or at.

Cheers

Mick

Bagmaker wrote:

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if you open the black box there should be a couple of terminals with the wiring attached to.
Between (or kind of between) the terminals there should be a small diode, half the size of a cigarette butt, probably black with a couple of colored lines going around it.
Without this diode the panel shouldn't be put in parrellel with other panels, they will drain each other of potential charge, especially in partial shade.
Its no big deal to fit a diode yourself.
99% sure it will have one but best to be sure

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 Hi Bagmaker

You are correct in asking him to check this but perhaps he does not have the knowledge to do so. In fact these house panels may have two or three diodes in there on the cell string connections. Mine do ! They do not usually fail so perhaps best left alone and see if they work ok if you do not know enough.  Get somebody to check them if there is a problem, as you said they can easily be changed with items from an electronics store.

NOTE for other peoples information do not pay big dollars for these diodes as some 4WD and solar retailers charge, "because they are special" or similar rubbish. Very ordinary spec items in electronics stores.

Jaahn   

This will do it .. Our old bus was 24v the house batteries where charged as 24v wired in series . BUT the feed to house batteries was still 24v to four 6 volt batteries . Then 12v off them . Had NO issues with any going flat over the other as they drawed off EACH battery evenly ., 24 in series while the 12v wired in parellel . Worked great for 8 years .

Aus-Kiwi wrote:

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This will do it .. Our old bus was 24v the house batteries where charged as 24v wired in series . BUT the feed to house batteries was still 24v to four 6 volt batteries . Then 12v off them . Had NO issues with any going flat over the other as they drawed off EACH battery evenly ., 24 in series while the 12v wired in parellel . Worked great for 8 years .

-- Edited by Aus-Kiwi on Wednesday 12th of July 2017 05:57:05 AM

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 Hi Aus-Kiwi

You have hijacked this thread The OP asked a straight question and i  answered it to help him. He is unfamiliar with the technology so it has taken a few answers. Another person has asked a relevant question which was also answered in several replies. All good I think ! Might be of help to others too

However you have thrown something different into the thread which I think will confuse !!  Now you have shown a picture of a PL60 regulator which is not suitable for the job the OP asked about  WHY ??

If you want to have a discussion about your experience with an unusual battery setup then START A NEW THREAD Plenty of forum space to go around. Others may have some experience and could contribute. Might be of interest to others.

Jaahn

Jaahn wrote:

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kezngaz wrote:

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Would the controller have to be able to accept 36.2 v
Or 45.3v, just for furure reference?
Thanks.
Kezngaz.

---

 Hi Kezngaz

The controller must be able to accept at least the Maximum panel voltage. But better ones and MPPT good controllers are usually rated at much higher voltages.

EG From the same Tracer unit the specs are 100V. So you can even use the panels in series. Which may have some advantages, perhaps ? However not to my liking with these 24V type panels on a mobile home/caravan roof. 90 volts DC is too high for me !  

Max VOC ---- 100V

Cheers Jaahn

-- Edited by Jaahn on Sunday 9th of July 2017 10:59:45 AM

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 Yes

Max 100V is getting to the quite dangerous stage,& close to where the Australian wiring rules & regulatios appply

Aus-Kiwi wrote:

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This will do it .. Our old bus was 24v the house batteries where charged as 24v wired in series . BUT the feed to house batteries was still 24v to four 6 volt batteries . Then 12v off them . Had NO issues with any going flat over the other as they drawed off EACH battery evenly ., 24 in series while the 12v wired in parellel . Worked great for 8 years .

-- Edited by Aus-Kiwi on Wednesday 12th of July 2017 05:57:05 AM

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 A lot of potential problems 

How did you ensure they drew from each 12V set evenly

How do you balance charge them, so that one is not overcharged or one undercharged

I suggest that readers do not attempt this

There are ways it can be done safely & easily ,but requires a 24v >12V DC converter 

T1 Terry wrote:

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I'm a bit lost here so maybe someone can explain the bit that doesn't make sense. The MPPT controller mentioned could handle the 2 x 185w panels in series or parallel as far as voltage is concerned, but isn't that controller limited to 10 amps @ 12v nom. output. If MPPT controllers really worked the way the salesman says then the combined 2 x 185w would equal 370w and a full conversion to 12v nom. would be over 30 amps, even higher if the battery voltage was less than 12v as in deeply discharged. Surely this means a controller capable of handling up to 100vdc input and 30 amps output min would be required, if they really worked like the salesman claims then more like a 40 amp output.
As far as max DC voltage goes and the electrical regulation.....

in the case of these 2 panels around a max of 72vdc ( Vmp of 36v x 2 panels) but likely to be even less than that, so reasonably safe if safe practices are followed.
Will any controller actually get 2 x 185w out of these 2 panels in normal solar conditions, no, to get a better idea of what (watt) can be expected assume roughly 70% of the rated output, anything more is bonus but can not be expected as a sure thing.
Did that help or muddie the water a bit more?

T1 Terry

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 Hi Terry

Actually it did not help as you are not quoting the correct figure. The recommended example i quoted is;

Tracer 3210A 30A MPPT Solar Charge Controller

As you can see it is rated at 30 Amps. As I said if you go off the panel watts then you will be OK.

As far as the max voltage of these panels in series goes, the voltage output of the panels mentioned is actually (off the spec plate) 45.3 Volts each OCV. So x2 is 90.6 volts max. That voltage may be available any time the sun is shining and the controller switches OFF with two panels in series. We know the panels will generate close to the OCV  any time they are OC even in moderate sun power. We also know that the voltage drops as a current is drawn from them. 

That voltage is too high for me I said. On my house roof it is OK but on a mobile roof it seems a bit high for the normal standard of insulation and workmanship found and the voltage to expect if you were working on the system.  My personal opinion despite the standard.  You can die from 60V up.

We know you are against MPPT regulators but not using one with these panels will reduce their output to around 75W each maximum so two in parallel will give 150`watts max. The rest is unusable. You might be able to work out why ??

Jaahn 

Hi Terry

Thanks for the apology on the Tracer 3210.  The OP was uncertain so more confusion was not needed. It would do his job.

As far as the lethal voltage goes, I have in previous times done some training courses on this very subject and have been told 60V can be a lethal voltage in some circumstances. I would consider 90v well up there and if the voltage is applied to one hand and the other hand is earthed the possibility of fibulation of the heart is real as the current passes that area. Soo not likely I will play with it. I say there is a real current available from those panels eg up to 5 A. Earth leakage units are set to only 30milli amps for safety.

Here is one site, lots out there with an opinion :  https://www.physics.ohio-state.edu/~p616/safety/fatal_current.html

Cheers Jaahn

PS Just for light relief I once worked on an old ship with 180 V DC system. Man you had to be careful with that, and did those wires burn out in a spectacular fashion on the deck gear, when the insulation failed with the salt water and the metal ducting and boxes. They would burn back about 50mm of say, 12mm dia cable with a very visible burn mark  Not too hard to find.

The boss blew the main board fuse one day, 800Amp rated. Everyone heard it all over the ship and came running. Not a short actually, but switched the small emergency generator onto the system with reversed polarity  hmmm...