Hi mate. I had the same problem. Only 200w flat on the roof. I had just installed a fridge in my Hilux with a battery charged from the car. I added an Anderson plug to that set up plus one on the side of my caravan connected to the van charger. I then purchased a 160w folding panel (without the controller) to boost the charge on both, at different times of course. The Hilux battery normally just needs a top up with the morning sun. Obviously pointed east before I go to bed. I made a three metre wire rope to secure the panel to the a bar. Not had a problem since and even an overcast day gives you a dribble of power. Oh yes also I al total 12v now including van fridge but I Di have gas bbq and diesel heater. Hope this helps. Col

Are the panels clean, is the wiring heavy enough & do you get a tiny shadow anywhere on a single panel.

iana wrote:

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Yes the panels are clean, shadows yes, cant help that, unless I remove the air-con and the skylights. The panels are wired in series, so while the wiring is a good size, wiring in series overcomes any voltage drop. During the summer we got over 30 amps coming in, but the passed few days only got a max of 17 amps.
I think that a portable 200 watt panel would help, so I can position it to follow the sun.

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 I was up in the flinders a few weeks ago.... 20 amps was common....  maybe high 20's occasionally is all I got out of my 800w....  and mostly only for the few hours when the sun was up a bit..... say 10:30 to 2pm ish.....   long shadows this time of year etc.

Noelpolar wrote:

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iana wrote:

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Yes the panels are clean, shadows yes, cant help that, unless I remove the air-con and the skylights. The panels are wired in series, so while the wiring is a good size, wiring in series overcomes any voltage drop. During the summer we got over 30 amps coming in, but the passed few days only got a max of 17 amps.
I think that a portable 200 watt panel would help, so I can position it to follow the sun.

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 I was up in the flinders a few weeks ago.... 20 amps was common....  maybe high 20's occasionally is all I got out of my 800w....  and mostly only for the few hours when the sun was up a bit..... say 10:30 to 2pm ish.....   long shadows this time of year etc.

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 Hi 

Let me say clearly that if you want to go free camping for a while you need to put in as much power every day as you use. You cannot go long on the batteries alone. So if they are getting lower each day you do not have enough charging. Perhaps the posters here already know that but others reading here may need this spelling out.

Soooo how to do that ! There are suggestion made here, all standard things for solar. MORE solar, check the solar has no shading, that it is working as well as it should, get portable panels to chase the sun better, cut back on usage, LED lights, etc. In winter down south the sun is lower and the days shorter so care will be needed to select your sites.

Then what alternative charging do you have. The first should be your engine alternator, the best charger you have. Dumb alternators will supply a high constant voltage at a high rate, so rig that up with good wiring and perhaps that is all you need. Smart alternators will need a dc-dc charger that is bigger than most people buy, to cut the run time to a reasonable short time. EG if 20 Amps it will take 6 hrs to put in 120Ahr. At 40 amps it will take 3 hrs to do that. Basic maths. 

A generator is the other means of charging. But if you have a 240V AC generator then you also need a big DC charger to get the power in to the battery in a reasonable time. So do the maths there too just like above. A small charger that charges over night is not big enough. I have a 12Vdc generator/charger that does 50Amps. I must admit that I never take it but it is an expensive but lighter option(aussie made too)   

Jaahn

PS  http://www.christieengineering.com.au/products/12-volt-55-amp/

FWIW.... for winter down south ..... I go for 4x Solar watts to battery AH (ie some would say 200w of solar for 100ah of battery.... I go 400w of solar to 100ah.... I use about 100ah a day..... so went with 200ah battery to 800w on flat van roof). Off course.... I only generally see my battery at 70% discharge as some of the 100ah consumed is straight from solar during the day.... so always have 2 or 3 days of really bad weather winter reserve.

In summer....  can tolerate some shade because of solar over provisioning for summer conditions. I went with 6 panels....   3 parallel strings of 2 panels in series....  so some series benefit (higher voltage, smaller cable, slightly longer mppt on time), with some parallel shading mitigation.

I also didn't want to manually handle panels.... just want to relax. Haven't used a 240v charger in 18 months....  so probally could have saved $260.

Craig1 wrote:

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Maybe a hijack, hopefully better than yet another thread. Is there an easy or simple way to check if panels are in series or parralell ? Had a dealer fitted single panel, then bought a same second panel off dealer, both 120w, but second panel fitted by local auto elec who has gone bush somewhere. He connected wires on the roof. Van is under carport at the moment which catches a little afternoon sun onto panels and according to input display in the boot ( around 14.8v-15.2).
thanks Craig

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 Craig, with that kind of voltage they will be in parallel. In parallel the voltage stays the same and the current doubles, in series the current stays the same and voltage doubles. 

Mamil wrote:

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Craig1 wrote:

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Maybe a hijack, hopefully better than yet another thread. Is there an easy or simple way to check if panels are in series or parralell ? Had a dealer fitted single panel, then bought a same second panel off dealer, both 120w, but second panel fitted by local auto elec who has gone bush somewhere. He connected wires on the roof. Van is under carport at the moment which catches a little afternoon sun onto panels and according to input display in the boot ( around 14.8v-15.2).
thanks Craig

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 Craig, with that kind of voltage they will be in parallel. In parallel the voltage stays the same and the current doubles, in series the current stays the same and voltage doubles. 

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 Hi Craig 

+1 Mamil has summed it up exactly 

If you had a PWM regulator then there is no benefit in using series, actually a waste of the new panel really. Series is only used for MPPT which can take the extra voltage and convert it to extra current

Jaahn

iana wrote:

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And just working on the above, I understood, that a battery required a higher voltage to get the final charge into the battery, i.e. finishing off the charge. On a cloudy day, the voltage of the panels is lower, and with a PWN regulator, the regulator is unable to get the batteries "finished off". With the MPPT regulator and the panels wired in series, the regulator can easily supply the 14.2v required and the batteries are then fully charged 100%. (if you have enough solar/time).

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 No. Any pretty much regulator can provide enough voltage to "top up" the batteries. The MPV (maximum power voltage) of most 12V panels is around 18V and the light needs to be quite low before that drops to under 14.2V. A good regulator will tell you what the current panel voltage being offered is.

But 14.2V is quite low and charging at 14.2V will be slow as the battery approaches that voltage. Depending on the batteries, most regulators would be set to a higher voltage than 14.2V for most of the charge in order that the charge rate is higher.

Cheers,

Peter

Peter_n_Margaret wrote:

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 No. Any pretty much regulator can provide enough voltage to "top up" the batteries. The MPV (maximum power voltage) of most 12V panels is around 18V and the light needs to be quite low before that drops to under 14.2V. A good regulator will tell you what the current panel voltage being offered is.

But 14.2V is quite low and charging at 14.2V will be slow as the battery approaches that voltage. Depending on the batteries, most regulators would be set to a higher voltage than 14.2V for most of the charge in order that the charge rate is higher.

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I might have mislead a little in my previous post.
The MPPT regulator will "finish off" a little quicker because it will offer some extra amps, not because of any voltage differences which as Iana's suggestion.
Those extra amps come from converting the "excess" panel voltage to the charge voltage. The PWM controller simply switches off (and on) to control the last bit of charge.
Changing the charge voltage from 14.2V to something higher will increase the charge rate too, provided it does not become excessive enough to start drying out the battery electrolyte. In this regard it is important to follow the battery manufacturer's recommendations carefully. I would also recommend the charger have temperature compensation.

Not all batteries are equal in this regard. The internal resistance of the battery has a significant effect on charge rate relative to voltage offered. This is one of the benefits of Lithium - they have lower internal resistance. And different brands of AGMs will have slightly different performance too.

I would conclude though that Iana is simply short of solar. It is nice to be able to get to full charge much earlier in the day without worrying about the last hour or 2 of daylight.
Cheers, Peter

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 Hi 

Good posts by Peter IMHO. Possibly Iana solar has shading problems with low winter sun as part of the shortage of solar. Tony resolved his with 53% more portable directional panels.  

I would make two points, firstly to get the correct charging voltages go to the battery supplier or manufacturer. There are lots of different voltages shown on the web so the manufacturer is the expert. I am with Peter and think 14.2 is low. I can point out that +0.2V makes a big difference here and +0.4V is even bigger. 

Secondly you must have a multi stage charging setup in whatever charger or regulator for efficient battery management. The minimum is three stage with BULK, ABSORBTION, FLOAT. And temperature compensation probe too if possible and necessary if the regulator is not beside the batteries. Having a proper lower float voltage eliminates the drying out problem completely.     

Jaahn

For those who are not sure always calculate total length + & - 

Whenarewethere, things could be made more efficient, however its not always practical or possible, I can for instance take off the panel that maybe subject to a bit of shade (I need to climb on the roof as see first), and use it as a portable. But that would be a nuisance, as I would have to reinstall it every time we moved. I don't think we do enough "Off the grid" camping to warrant any major mods such as being able to angle the roof panels, but that would help.

The regulator is a GSL  MPPT60-1

Thanks Ian.

-- Edited by iana on Friday 24th of July 2020 07:08:29 AM