Camping solar panel advice

[stallie]

With technology changing all the time and things getting cheaper, I thought i'd canvas some opinions for a solar panel that I intend to mount on my roof rack for long 4wd trips bush.

I've settled on a 120W as the approximate size I need (as I'll be running a 50lt fridge and LED lighting in the camper trailer, for now, but might be more in the future).

There will be a dual battery in the car (Optima 34M) being charged from the alternator when driving and the solar panel when not. I will also have another small AGM battery in the camper trailer for LED lighting, occasional fridge use (normally left in back of car) and phone charging etc.

Now there are several options.

Option 1 - Ebay - $194 Mono Solar Panel Home Power Generator Battery 120W | eBay (http://www.ebay.com.au/itm/Mono-Solar-Panel-Home-Power-Generator-Battery-120W-/260849557481?pt=AU_Solar&hash=item3cbbd85fe9#ht_5707wt_1156)

25 year warranty, but the seller won't be around to uphold it I'd say.

Option 2 - Jaycar -$425Powertech Monocrystalline Solar Panel - 120W - Jaycar Electronics (http://www.jaycar.com.au/productView.asp?ID=ZM9098)

Looks like it's from the same factory - but twice the price...

Option 3 - EverybatteryBattery: Powertech Monocrystalline Solar Panel: 120W, Monocrystalline Solar Panels, ZM9098 (http://www.everybattery.com.au/proddetail.php?prod=ZM9098)

Looks identical to Option 2, same specs anyway...


So do I chance the half price ebay one from what is probably a fly by night seller expect no warranty or buy the twice the price one?

[Blknight.aus]

Ive taken to advising people to set up their units as doubles.. if you need 120W you set up a pair of 60W panels and give each its own solar regulator
Theres a few advantages

if you damage one panel your not out for a single expensive replacement and you still get some solar use out of it.

If you meltdown a regulator you still have one working

you can put the panels in different positions (its often easier to find 2 smaller areas to put up the panels than one bigger one and the smaller panels are easier to handle)

If you cant afford to go straight to full setup in one go you can piecemeal it up.

[Bushie]

After a bit of advice,

I have a (new) 120W folding panel, over the weekend I set up the fridge , solar panel, and battery (10yo Optima) to see how it performed.

Seemed to go OK out in the backyard (ie out of the landy) 3 days running the fridge swapping drinks in and out of the fridge (Fri/sat ~ 26deg today fairly heavy overcast all day ~ 24deg), so that side I'm happy with.

The question when there was no load on the battery ie fridge cycled off, then the voltage at the battery was reading ~16.5v as soon as the fridge came on the voltmeter dropped to reading around 12.6v.

Does this seem right ? I'm a bit concerned at the high voltage although there was no current passing (admittedly with an old car ammeter)

The panels have this regulator (http://www.jutasolar.com/en/product_more.asp?id=1185)


Martyn

[Blknight.aus]

sounds like the panel is bypassing the regulator.

[Tank]

I would have the panels portable so as you can set the panels in the sun and your LR in the shade, esp. if you have the fridge in the LR. I park in the shade and put my panels (folding briefcase type from K-Mart $90 on special) in the best possy in the sun and move them to follow the sun, a lot easier and cooler than having the panels fixed to the LR, Regards Frank.

[Judo]

When I bought mine a while back I got it from this ebay store that is operated local in Melbourne.

eBay: lowenergydevelopments (http://stores.ebay.com.au/Low-Energy-Developments)

You can also email them with any questions before hand and arrange local pick up from Preston, Melbourne. It was a great service and they were the cheapest of all priced at the time.

[harlie]

You will amazed at how inefficient panels are when they are mounted flat. Our tests based on our boat installation (2x120w BP units originally mounted flat) have shown that having the panels portable so they can be faced directly at the sun will produce about 3 times the power (total AH) for the day. Even midday in winter, output climbs by over 24% by tilting panel toward north by 40deg(ish) - keep tilting up untill the shadow on ground gets to it's largest. Unfortunately due to space restrictions on a boat the best I can do is a swivel mount that tilts them fwd/aft, still a big improvement.

My camping panels (2x80) are portable with 12m of 6mm cable (regulator at battery end) with another 8m length available if we have heaps of trees, all connected with andersen plugs. If you mount flat on the top of car, get double what you think you need.

[harlie]

The question when there was no load on the battery ie fridge cycled off, then the voltage at the battery was reading ~16.5v as soon as the fridge came on the voltmeter dropped to reading around 12.6v.

Does this seem right ? I'm a bit concerned at the high voltage although there was no current passing (admittedly with an old car ammeter)

The panels have this regulator (http://www.jutasolar.com/en/product_more.asp?id=1185)


Martyn

That actually looks like the same cheap arse regulator I take camping! Mine came in a kit, and I assumed (and budgeted) that I would chuck it and get a decent one, but it has performed quite well. It has 2x80 panels feeding it and V measured at the elec panel never goes above 13.6. First thing in the morning when things are cool and the batt is down a bit I see over 9.2amp, this of course drops as V approaches 13.6, and it will hold V at 13.6 all day (with 60L evacool running) until panels loose light. I increased output by about 30% (7.1 to 9.2 amp) by getting rid of the small cable, replacing with 6mm ($50), and taking the regulator off the panels and mounting beside the battery – this way the high voltage on the panel side (~21v) is taking the voltage drop over the long cable and the very short run to the battery allows the regulator to sence the lower voltage better.

Sounds to me like it is hooked up incorrectly or not working correctly - if you have 16.5v at the battery, I would consider that closed circuit, panel will be about 19-21V, minus voltage drop of the wire (no doubt quite small diameter), minus internal resistance of old battery and change of state inefficiencies ect ect and that would be about right, you wouldn't see much current at that level and your poor battery is in hell.

Dropping to 12.6 with fridge under heavy cloud I would expect with cheapo panels. I’ve notice low light (heavy cloud) performance with my camping kit no where near as good as the BP kit, to the point where the BP panels output near 30% of capacity as apposed to 10-12% for the cheap ones (that’s side by side operating!).


As a side note – when shopping for my camping kit I found quite a few (cheaper) sellers pushing panels that were not as big as they stated. The kit I bought was advertised as “240w folding solar panel kit”. When I enquired for spec, I deduced that it was more like 160w (I have 120 watt bp units on the boat, so I know how big they should be) – still really cheap so I got it: testing as per Aus standards puts the kit at 170w, so I call it pair of 80 watt panels. So beware of the cheap panels.

[Bushie]

That actually looks like the same cheap arse regulator I take camping! Mine came in a kit, and I assumed (and budgeted) that I would chuck it and get a decent one, but it has performed quite well. It has 2x80 panels feeding it and V measured at the elec panel never goes above 13.6. First thing in the morning when things are cool and the batt is down a bit I see over 9.2amp, this of course drops as V approaches 13.6, and it will hold V at 13.6 all day (with 60L evacool running) until panels loose light. I increased output by about 30% (7.1 to 9.2 amp) by getting rid of the small cable, replacing with 6mm ($50), and taking the regulator off the panels and mounting beside the battery – this way the high voltage on the panel side (~21v) is taking the voltage drop over the long cable and the very short run to the battery allows the regulator to sence the lower voltage better.

Sounds to me like it is hooked up incorrectly or not working correctly - if you have 16.5v at the battery, I would consider that closed circuit, panel will be about 19-21V, minus voltage drop of the wire (no doubt quite small diameter), minus internal resistance of old battery and change of state inefficiencies ect ect and that would be about right, you wouldn't see much current at that level and your poor battery is in hell.

Dropping to 12.6 with fridge under heavy cloud I would expect with cheapo panels. I’ve notice low light (heavy cloud) performance with my camping kit no where near as good as the BP kit, to the point where the BP panels output near 30% of capacity as apposed to 10-12% for the cheap ones (that’s side by side operating!).


As a side note – when shopping for my camping kit I found quite a few (cheaper) sellers pushing panels that were not as big as they stated. The kit I bought was advertised as “240w folding solar panel kit”. When I enquired for spec, I deduced that it was more like 160w (I have 120 watt bp units on the boat, so I know how big they should be) – still really cheap so I got it: testing as per Aus standards puts the kit at 170w, so I call it pair of 80 watt panels. So beware of the cheap panels.


Been back in touch with the guys that sold the panel after a quick voltage check he said sounds like the reg isn't working and would put a new one in the mail, that was last Thursday, today I have a package to pick up at the post office, so I'm assuming that's what it is - certainly can't complain about anything at this stage, may take the opportunity to remote mount the reg near the battery.


Martyn

[harlie]

These regulators use Pulse Width Modulation switching a Mosfet to regulate flow. If the Mosfet has fused closed then you will have a closed circuit like you are seeing.