Solar panels for camping

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Wow...i liked the look of those flexi panels...i was going to get some and sikaflex them too my roof on the d40...might rethink that
 
Hi Cam, that is what I have read on the caravan forum not that I look at it often, one poor old bloke spent 2 days trying to remove the sikaflex, I just use a 120 watt cheapie on a 7mtr lead managed by the Ctek. I like to camp in the shade and run that out into the heat. Runs 2 fridges no problem for day's without idleing provided it's not overcast.
 
Solar panel ratings are often misleading and at the very least confusing.

Without a load on the panel, it will read a particular voltage - called the 'open circuit' voltage. Kind of like the voltage you read on a battery that's not connected to anything. Once you put a load on it, the voltage drops - the greater the load, the greater the drop until you reach the maximum current output of the panel.

Maximum current output is NOT achieved at maximum voltage (because max voltage is when there is NO load at all). However, manufacturers rate their panels in watts and a glib salesman will even pull out Ohms Law to show you that Power (watts) = I (amps) times V (volts). This is absolutely correct, but there are 4 different ways to get the result.

The honest way: the amps produced under peak load (sometimes referred to as the Max Power Current) times the voltage under peak load (Max Power Voltage) = panel watts. One of the panels I looked up on eBay had the peak volts at 17.82V and peak current at 8.9A, which results in 159.598Watts - close enough to the claimed 160W.

What they COULD have done was use the open-circuit voltage times the short-circuit current, in this panel's case that was 10.68A times 21.96V = 234.53Watts.

That's outrageously high, but there's nothing stopping an unscrupulous trader from taking the short-circuit current times the open-circuit voltage on an 80W panel (from another example on eBay, 5.1A times 22.5V = 114.75W and try off-loading it as a 100-120W panel. You'd believe it until you tried using it and only got the 4.45A that an 80W panel is capable of.
 
Ok, im not 100% if my amp reading are correct, but im absolutely stoked with how my panel & ctek are working.
Yesterday arrived at camp at 12pm with a full battery.
Checked at 7pm b4 dinner & battery was 100%.
Weather was 23 deg with cloudy periods.
Overnight, only 9amps was consumed (fridge thermostat turned down a setting on the evakool dial).
Now at 2pm its 100% again.
Fridge temp maintaining 1 deg rear half or the fridge & -1 front half.
 
Perfect!!! Mine ran for 3-4 days unchecked last week before the battery was flat...fridge and bevos were still frosty as! Go the solar panels!!!!
 
Mabee....gets some morning shade where its parked...but a solid 4-5hrs of full sun..they are glued to the top of my toolbox in the tub.only 2x20w panels too with a ebay mppt controller...i measure 2 amps in full sun..as i dont camp for long that much i havnt worried
 
Yeah its great mate! I was sick of always worrying about how much i was flattening the battery & trying to run an ext cord to power it by 240v wherever possible
Now wherever i go, i can jst about forget its there....except for when i want to grab a cold one
 
Mabee....gets some morning shade where its parked...but a solid 4-5hrs of full sun..they are glued to the top of my toolbox in the tub.only 2x20w panels too with a ebay mppt controller...i measure 2 amps in full sun..as i dont camp for long that much i havnt worried

Your doing well with 40 watts, that's a tad more than the fridge will draw, if you double that power it should recover the next day and maintain close to full charge.
 
Interesting reading this old thread how much solar panels have changed in the last five years. By this I mean price drop and capacity increase.

The aluminium frame panels weigh in at 15 to 20 Kg for 200watts
The same in flexible solar panel is 3Kg
Prices are much the same for framed or flexible so that is no longer a decision point.
I have read comments saying the flexible are no good - rusting rivets and cracks in the wafers.

Has anyone tried the flexible solar panels ?
 
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We always gotta remember average current draw ratings for fridges relate to keeping a fridge at 4 degrees celsius in "ambient temperature"

Some fridge companies allow for 20 degrees ambient 24 hrs a day, whereas the real deal fridges like national luna allow for 20 degrees at night, 30 degrees in the morning and 40 degrees in the afternoon

If you want to sell more fridges, you can claim anything you like because the average consumer is incapable of working out the particularities in physics that apply to their situation, and the mathematics required to work it out

None of the marketing for auto fridges allows for all the times you open the fridge during the day allowing cool air to escape

Or putting anything into that fridge throughout the day that is not already at 4 degrees celsius
 
Interesting reading this old thread how much solar panels have changed in the last five years. By this I mean price drop and capacity increase.

The aluminium frame panels weigh in at 15 to 20 Kg for 200watts
The same in flexible solar panel is 3Kg
Prices are much the same for framed or flexible so that is no longer a decision point.
I have read comments saying the flexible are no good - rusting rivets and cracks in the wafers.

Has anyone tried the flexible solar panels ?
I have heard good and bad reports about these panels. It seems of late they have improved, but many still have less output than the claimed amount. Lots of vans getting around with them glued to the roof.
 
Ive got this one sikaflexed to the top of my d40 canopy.

http://m.ebay.com.au/itm/180W-12V-F...er-Mono-Charging-Kit-/282184717705?nav=SEARCH

It was from a different seller and i got it for $260, but im sure that's it

It pumps out around 8-9 amps at 14 volts in full sun

Thats a bit less amperage than 180w should be but most specs are exaggerated with Chinese gear

Seems to do a really good job though i put my auxiliary battery through hell and its always fully charged now that i have a panel
 

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