Camper trailer solar set up

[landy]

Hi all,
I need some advice from the solar gurus. I've decided to get some panels for the camper. But now I'm just confused. I have 2x 105 amp deep cycle batteries on the camper. We run 2x LED strip lights and an 80 litre Weaco fridge. I also have 2x small LED lights and USB chargers by the bed. Other than that we don't power to much.
So my questions are, 1. Is a 140w folding mono panel enough for my needs and 2. Will I need a CTEK D250s or similar. The camper has a Projector DC-DC charger but I'm not sure if I can connect a solar panel to it.

Thanks

Nino

[fraser130]

I would be very surprised if 140w didn't cover it if you had "nice sunny days".
I would buy a good quality MPPT regulator (NOT a cheap one) like This (http://www.ebay.com.au/itm/EPsolar-Tracer-2215RN-MPPT-Solar-Battery-Charge-Controller-20A-Remote-Meter-MT5-/251302352227?pt=AU_Solar&hash=item3a82c99563) one. (I have the same unit and a 120w folding panel, we have 150Ah storage, charge laptops(2) ipads(3) ipods (?) run led lights, and usually power several other family campers too. the big difference is we have a gas fridge, but our batteries are usually fully charged by 11am. this is Victorian summer conditions.
The good thing about that reg (in your case) is it can take up to 260w, so you could add more panels later. If you do go for a "proper" MPPT regulator, make sure you get your panels to run at 24v if you can as this helps heaps with the voltage drop over the cables from the panels and allows you to place them further away in the sun.

Cheers,

Fraser

[Maelgwn]

What is your typical use?

Do you want to be able to run off solar indefinitely? Or just hoping to add an extra day or two to your battery life before needing a recharge from driving/home?

[Owl]

Hi Nino,
As already noted, it depends on your intended use.

I regularly camp up for 2 weeks in Victorian winter. I power a 20+ year old 39L Engel fridge (read - not very efficient anymore), LED lights, and recharge laptop, pad, satphone, and sundry other batteries.
My setup is 3 x 100Ah deep cycle batteries charged with 2 x 110W mono-crystalline solar panels, and a Redarc (http://www.redarc.com.au/products/product/in-vehicle-battery-charger-40a/) MPPT/DC-DC charger. Battery state of charge is monitored with a Xantrex (http://www.xantrex.com/power-products/power-accessories/linkpro-battery-monitor.aspx) Link Pro monitor.

My worst case situation was after 5 days of heavy overcast/rain, there was still enough solar input to prevent the battery state of charge (SOC) dropping below 70%. One day of sunshine following this had the batteries back to 100% SOC. Since it is advisable to not let the battery to go below 50%SOC, and since I'm unlikely to stay put for more than 5 days under similar conditions, what this means is that I have a little too much battery/solar for my requirements. Still - it's nice to have some reserve.

So what are your requirements from your solar setup? If you're not planning to camp up for longish periods of time in southern winters, then I would imagine that your 140W solar with a good MPPT controller and 210Ah battery should be more than adequate.

The Ctek D250S will give you automatic change over between solar/car charging, but is really only an advantage if your solar panels are permanently connected. If your solar panels are stored away while traveling, and setup after setting up camp, then there is no real advantage.

Good luck with your decisions
Ian

[TeamFA]

G'day Fraser!

Sorry to sidetrack the thread a little, but...

I recently purchased and installed a Tracer 2210RN solar charge controller, with the MT5 remote unit.

I haven't had any problems with it using it, though I seem to have a slight inconsistency with what it reports as the battery's state of charge.

It's connected to our auxiliary battery, which charges from the car after a Redarc isolator.

After a drive long enough to top up both batteries, I get a voltage reading - after it settles - of 12.7V on the battery. I understand this is pretty much a 100% reading, however when you cycle through the display on the MT5 unit, and the bar gauge correlates this - it's only reporting the battery at 60% charge.

My concern is that when I connect the solar panels, the controller will think the battery is not fully charged, and try to overcharge the battery.

I've only had the panels running for a short amount of time since installing the controller. The only thing I can think of is that I need to have it charging for a while for the controller to properly ascertain the state of charge of the battery.

I've been through the manual for both the controller and the MT5 remote unit, and can't find anything that helps...

Thanks!




I would be very surprised if 140w didn't cover it if you had "nice sunny days".
I would buy a good quality MPPT regulator (NOT a cheap one) like This (http://www.ebay.com.au/itm/EPsolar-Tracer-2215RN-MPPT-Solar-Battery-Charge-Controller-20A-Remote-Meter-MT5-/251302352227?pt=AU_Solar&hash=item3a82c99563) one. (I have the same unit and a 120w folding panel, we have 150Ah storage, charge laptops(2) ipads(3) ipods (?) run led lights, and usually power several other family campers too. the big difference is we have a gas fridge, but our batteries are usually fully charged by 11am. this is Victorian summer conditions.
The good thing about that reg (in your case) is it can take up to 260w, so you could add more panels later. If you do go for a "proper" MPPT regulator, make sure you get your panels to run at 24v if you can as this helps heaps with the voltage drop over the cables from the panels and allows you to place them further away in the sun.

Cheers,

Fraser

[POD]

A lot depends upon the conditions you are camping in. Camping in 40 degree heat, for example, will cause your fridge duty-cycle to be much greater than if you were camping in a southern winter, so your amp-hour requirement to run the fridge over a 24-hour period might be tripled. Running LED lights for a couple of hours in the evening won't draw much at all, but older, less efficient lights can draw more than your fridge.
In the Kimberley this year, I had similar power requirements to what you describe; Engel fridge, LED strip lights, plus occasional brief use of the HF radio. In places where I could keep my 120watt panel in the sun, it produced enough power to camp indefinitely. One spot where we camped with a lot of shade, I could only keep it in the sun for about 4 to 5 hours a day, and ended up having to run the car for an hour every second day to top up the battery.
Having at least 10 meters of heavy cable will help, the 5 meter length that most panel sets are provided with is nowhere near enough to keep the camp in the shade and the panel in the sun.

[POD]

Another thing that I found helped quite a lot was to have the voltage regulator at the battery end of the cables; the folding panel set that I bought had a regulator attached to the panels, this means that you get the regulated 14-point-whatever volts, MINUS the voltage drop over the length of the cables. Moving it to the battery end means that the voltage is regulated AFTER the voltage drop of the cables, this can make a significant difference to the power getting to the battery. A tip I picked up somehwere on this forum.

[fraser130]

Hello!
I find the SOC indicator is only an approx. indication, and it also assumes no other source of power, and it needs all the load to be shunted through the reg, as well as the type of battery and the capacity of the battery to be programed in. To try and get an accurate SOC the batt also has to sit for about an hour with no load!
It also is highly dependent on the condition of the battery too.
if the battery type is set correctly, don't worry, it will not overcharge it, you will see the charge current drop very quickly , then it gives small boosts every now and then. as long as the battery type is set correctly, you have nothing to worry about.


Cheers,
Fraser

PS - the SOC reading is independent of the actual charging process too


G'day Fraser!

Sorry to sidetrack the thread a little, but...

I recently purchased and installed a Tracer 2210RN solar charge controller, with the MT5 remote unit.

I haven't had any problems with it using it, though I seem to have a slight inconsistency with what it reports as the battery's state of charge.

It's connected to our auxiliary battery, which charges from the car after a Redarc isolator.

After a drive long enough to top up both batteries, I get a voltage reading - after it settles - of 12.7V on the battery. I understand this is pretty much a 100% reading, however when you cycle through the display on the MT5 unit, and the bar gauge correlates this - it's only reporting the battery at 60% charge.

My concern is that when I connect the solar panels, the controller will think the battery is not fully charged, and try to overcharge the battery.

I've only had the panels running for a short amount of time since installing the controller. The only thing I can think of is that I need to have it charging for a while for the controller to properly ascertain the state of charge of the battery.

I've been through the manual for both the controller and the MT5 remote unit, and can't find anything that helps...

Thanks!

[d2dave]

If you do go for a "proper" MPPT regulator, make sure you get your panels to run at 24v if you can as this helps heaps with the voltage drop over the cables from the panels and allows you to place them further away in the sun.

Cheers,

Fraser

I don't know much about the 24v option but what I do know is this.

If you have your regulator near the battery and not at the panel/s (like the plug and play kits have) voltage drop with reasonable size cable will not be a problem, as the panels are out putting around 21 volts, so a small loss does not matter.

With 160 watts I use 6mm auto cable which is really only about 4.5mm. I have run up to 40 metres of this and it works fine.

[fraser130]

I don't know much about the 24v option but what I do know is this.

If you have your regulator near the battery and not at the panel/s (like the plug and play kits have) voltage drop with reasonable size cable will not be a problem, as the panels are out putting around 21 volts, so a small loss does not matter.

With 160 watts I use 6mm auto cable which is really only about 4.5mm. I have run up to 40 metres of this and it works fine.

Dave, I agree 100% that the reg should be next to the batteries, I was just meaning that if you put the panels in series, you will halve the loss for the same power. Or you can double the length of the cable or use cable half the size and have the same loss.

Fraser

[TeamFA]

Thanks Fraser!

I've checked the reading after sitting for various lengths of time, as well as after and during loads. I also have all load shunted through the regulator (as I wanted to keep an eye on current draw for everything using the battery).

After some further looking around, it appears as if the % displayed on the remote unit is flawed, and supposedly admitted to by the manufacturer:
Amazon.com: Martin Sauer "Headguy"'s review of MT-5 LCD Display Remote Meter for Solar Re...@@AMEPARAM@@http://ecx.images-amazon.com/images/I/41n3kNa8Y5L.@@AMEPARAM@@41n3kNa8Y5L

Amazon.com: Customer Reviews: MT-5 LCD Display Remote Meter for Solar Regulator, Come with 2 Meters Cable, for Tracer MPPT series Tracer1210RN, Tracer1215RN, Tracer2210RN, Tracer2215RN, Tracer3215RN, Tracer4210RN (http://www.amazon.com/MT-5-Tracer1210RN-Tracer1215RN-Tracer2210RN-Tracer2215RN/product-reviews/B00ECVWDGC/ref=cm_cr_dp_synop?ie=UTF8&showViewpoints=0&sortBy=bySubmissionDateDescending#R3D0K3X6OQ6JH7)

We've just returned from 10 days on our property, using this controller to keep our battery charged from panels, running our 92l fridge/freezer, and on all but the rainiest of days, the regulator/panels had no problems keeping the battery charged.

Cheers!
Michael.


Hello!
I find the SOC indicator is only an approx. indication, and it also assumes no other source of power, and it needs all the load to be shunted through the reg, as well as the type of battery and the capacity of the battery to be programed in. To try and get an accurate SOC the batt also has to sit for about an hour with no load!
It also is highly dependent on the condition of the battery too.
if the battery type is set correctly, don't worry, it will not overcharge it, you will see the charge current drop very quickly , then it gives small boosts every now and then. as long as the battery type is set correctly, you have nothing to worry about.


Cheers,
Fraser

PS - the SOC reading is independent of the actual charging process too

[drivesafe]

Hi folks and Landy, for a starter, providing you have run suitably sized cabling between the cranking battery and your house batteries, you will have no need nor benefit from fitting any form of DC/DC device.

If your house batteries are in a low state at the beginning of the days drive, neither your alternator or a DC/DC device will fully charge your batteries, but your alternator will replace far more of the used capacity of your house batteries that a DC/DC device could do.

Next and this may be a bit confusing if you are not use to working with watts, but watts measurements are far more relevant when working with solar power supplies.

So keeping the above in mind, when calculating the power available at the house batteries, you need to know the total watt output of the panels and the total watts being supplied, via a solar regulator, to the house batteries.

The thin cable causes heat lose, heat uses watts to create the heat, and thats lost watts.

If you have 150 watts coming from the solar panels but you use thin cabling between the panels and the regulator, it doesn't matter if the regulator is mounted on top of the battery, if there is a reduction in the amount of watts available at the input of the regulator, then there is going to be a reduction in the current ( watts ) at the batteries.

Best suggestion Landy, as others have posted, get a good quality MPPT regulator and some decent cabling to connect the solar panels to the house batteries, via the regulator.

[d2dave]

Tim. I know that this type of stuff is your specialty, but the bloke I purchased my solar panels from also had a very broad knowledge of solar and electronics.

He owned a Jaycar store which he ultimately closed and took a job in a mine doing solar installations.
This was pre Kevin Rudd, so was long before the solar craze took off, where every one can easily become a solar installer, not necessarily an expert in the field.

Now this bloke told me what I posted in post nine, that being a small voltage drop through long cables does not matter.(if reg is close to the battery)

Obviously you would not want to use phone cable.

In my situation I have two 80 watt panels. One for the car with Engle, and one for the caravan house battery.

Each of these is fed by a 20 metre 6mm auto cable, which from memory is a bees dick over 4mm squared.

If we get a couple of cloudy days, I put the two panels to the fridge and have at times to get them out of the shade, join the two cables together to make a 40 metre run.

Using my Plasmatronics regulator which measures input, there is no measurable difference whether the cable is 20 or 40 metres..

[drivesafe]

Hi Dave and in your case, you are not charging low batteries, you are simply supplying energy for a set current load.

If for example, say your fridge draws 3 amps and your panels, on a cloudy a day, produce 2 amps each at each panel's output, then loose an amp over the cable length, but you still get your 3 amps.

If on the other hand, your were trying to recharge a low battery, your are more likely to have 2 amps coming from each panel, at the panels but because of the "ATTEMPTED" high current draw of the low battery, which will cause a greater voltage drop, you might be lucky to get 1.5 to 2 amps at the battery.

Thats the same setup but different results because of the different current loads.

NOTE, I did this in amps, not watts but you would actually see better figures if you were doing a watt count rather than an amp count.

The higher current draw of the low battery will cause a far greater voltage drop and that means wattage lose because of the heat generated in the cable.

Your mate was right but he didn't stipulate the size of the cable and in your case, the loses in the 6mm is fine for your fridge, but would cause a totally unacceptable loss when trying to charge a low battery.

[TerryO]

In the caravan industry most solar stuff ups are caused by the van builder using to small a cabling from the panels to the regulator and that is over very short distances compared to the long runs used with mobile fold up panels.

Having decent sized good quality cabling is one of the more important parts of any good solar system if you want to get the most out of it.

We only have 2 x 100 amp AGM's in our 18 foot van and two very good quality 135 w panels plus a good quality regulator. We use heaps of power, with a 60 litre chest fridge going 24/7, fans on all day, stereo going all day, plenty of lights on inside and outside the van and usually TV at night. In the warmer months no matter how much power we use in a day the next morning the regulator is usually on float by 8.00 am to 9.00 am (ish). Meaning all day while the sun is up we are only using the excess power the solar provides on fully charged battery's, most of our friends we camp with take advantage of that even though they have their own various mobile solar set ups. After a day or two of camping when their battery's start to run down each day or two between them they carry over their chest fridges and plug them into our vans batterys hoping to let their systems get half a chance to get enough power to keep their fridges going overnight. This happens all the time and with many different friends.

If you have to rely on running your vehicle or a genie to keep your battery's up with a decent charge in them then your solar system is inadequate for your power needs. Of course weather can and does make a difference but few of us sit in one spot for days and days on end if its bucketing down.

Having a good solar set up for me makes the difference between a great camping experience and a pain in the arse trip.

I invited Tim (Drivesafe) to this thread after reading it because I knew he would explain solar and what's needed better than me.

[mijango]

In the caravan industry most solar stuff ups are caused by the van builder using to small a cabling from the panels to the regulator and that is over very short distances compared to the long runs used with mobile fold up panels.

Having decent sized good quality cabling is one of the more important parts of any good solar system if you want to get the most out of it.

We only have 2 x 100 amp AGM's in our 18 foot van and two very good quality 135 w panels plus a good quality regulator. We use heaps of power, with a 60 litre chest fridge going 24/7, fans on all day, stereo going all day, plenty of lights on inside and outside the van and usually TV at night. In the warmer months no matter how much power we use in a day the next morning the regulator is usually on float by 8.00 am to 9.00 am (ish). Meaning all day while the sun is up we are only using the excess power the solar provides on fully charged battery's, most of our friends we camp with take advantage of that even though they have their own various mobile solar set ups. After a day or two of camping when their battery's start to run down each day or two between them they carry over their chest fridges and plug them into our vans batterys hoping to let their systems get half a chance to get enough power to keep their fridges going overnight. This happens all the time and with many different friends.

If you have to rely on running your vehicle or a genie to keep your battery's up with a decent charge in them then your solar system is inadequate for your power needs. Of course weather can and does make a difference but few of us sit in one spot for days and days on end if its bucketing down.

Having a good solar set up for me makes the difference between a great camping experience and a pain in the arse trip.

I invited Tim (Drivesafe) to this thread after reading it because I knew he would explain solar and what's needed better than me.

Sounds like you have a good setup Terry. Where did you source your kit?

[DeanoH]

Dave, I agree 100% that the reg should be next to the batteries, I was just meaning that if you put the panels in series, you will halve the loss for the same power. Or you can double the length of the cable or use cable half the size and have the same loss.

Fraser

Actually the power loss will be quartered.

Doubling the voltage halves the current and halving the current halves the voltage drop across the cable. As Power (loss) = Voltage (drop) X Current, ie. 1/2 X 1/2 = 1/4 :D, so in fact you can use quadruple the length of cable or use cable a quarter the size and have the same loss. :D:D

Just be very sure the solar reg used is capable of running '24 volt' in for a '12 volt' output if running a 12 volt aux battery. Not all regs are capable of doing this properly.


Deano :)

[drivesafe]

Hi Deano and 24v solar setups for 12v battery systems are only an advantage where there is a necessity for a long run of wiring between the solar panels and the battery.

If you are setting up a system where the panels are 15-20 metres or more from the battery, then the over all cost can be reduced by using a 48v solar set up and thinner wire/cabling, but there is still a wattage lose.

As most RV solar setups require 10 or less meters of cabling between the solar panels and the battery, the cost of thicker cabling is validated by the lower wattage loses and the simpler system setup.

So if you know you are always going to have to have a long run of cable between your solar panels and your battery, then specifically setup for a 24v system.

But as above, with most RV type solar setups, a 12v solar array with thick cabling is a better and simpler way to go, even if on occasions, you fined you need to use a long ( but temporary ) extension cable, where you will, on those occasions, loose wattage while using the extension cable.

[DeanoH]

Hi Tim, as you say a 48 volt system can be more trouble than it's worth. I'm not advocating this as a solution but highlighting the common misconception that doubling the voltage halves the (transmission) loss when in fact it quarters the loss in the 24 volt example described by fraser130. For a' 48 volt' system the loss would be quartered again for a loss of 1/16 that of a 12 volt system. :D Very significant for a remote panel stationary installation but, as you say .............. "Best suggestion Landy, as others have posted, get a good quality MPPT regulator and some decent cabling to connect the solar panels to the house batteries, via the regulator".

I have series connected '12 volt' panels to overcome problems with some cheap ebay '12 volt' panels that have too low an output voltage to be much practical use on their own. A tip for the unwary, a '12 volt' panel should have a Voc of around 21 volts and a Vmp of around 18 volts.
A couple of my mates bought these for the same application as the OP and got caught out. The eBay add selling these panels had a big yellow sunflower or daisy in the add so beware as they were not much use used singly or paralleled as a 12 volt source, which IMO should have been pointed out in the add.

Deano :)

[drivesafe]

He Deano and please note the typo corrections in my last post.

I meant 12v and 24v solar systems, but the results are still the same, you have a far simpler setup, that will achieve low loses just by using thicker cable over the typically shorter cable runs found in RV setups.

[drivesafe]

I have series connected '12 volt' panels to overcome problems with some cheap ebay '12 volt' panels that have too low an output voltage to be much practical use on their own. A tip for the unwary, a '12 volt' panel should have a Voc of around 21 volts and a Vmp of around 18 volts.
A couple of my mates bought these for the same application as the OP and got caught out. The eBay add selling these panels had a big yellow sunflower or daisy in the add so beware as they were not much use used singly or paralleled as a 12 volt source, which IMO should have been pointed out in the add.

Deano :)

This is one of a number of reasons I never recommend ANY specific brand of CHEAP solar panels, there are too many substandard panels out there now.

[drivesafe]

I can recall a similar situation about 10 years ago, where a well known electronics brand, came out with cheaper panels that were slightly larger than the other panels on the market at the time, but worked far better in shaded situations than any other well known panels could.

But while these panels came with the standard 20 year warranty, many solar installation companies were forced to replace them ( usually with other brands ) after just 18 months.

So again, I try to stick to the well known brands, recommended to my by the different solar installation companies I supply to.