Camper Trailers Tech Tips

Topraysolar 13watt portable solar generator





13W Portable Solar Generator
affordable solar for fridgeless campers

    While we don’t use a fridge at camp, we do have a battery for lighting, charging USB items and also on occasion to run the laptop or a little TV. The battery is a large “wet” starting unit fitted under the bed at the rear of the trailer. Because of the gases produced when fast charging, I would normally take the battery out, however it is reasonably heavy and awkward to remove/refit. A small solar panel appeared to be a good way to keep the battery topped up with much less risk of an explosion (the battery area is vented but you never know).

    With Easter fast approaching I was on the lookout for a suitable panel when, as luck would have it, both K-Mart and Repco advertised “briefcase” arrays on special. Both claim 13 watt output but I favoured the Repco one as a separate charge regulator is included. The K-Mart unit appears to be the same brand but a different (older?) model, rebadged as Jackaroo. The array I purchased is marketed as a “Portable Solar Generator”, TOPRAYSOLAR model TPS936N. The Repco Easter catalogue price was $99.

    The unit uses two solar panels (each 295mm x 440mm) mounted in plastic backed frames joined by a hinge. The outer edges of the frames are covered in a rubberised material and the whole thing feels quite solid when closed up, just as well as it is quite weighty. Opening the unit requires pulling the “handles” apart with the tips of your fingers – could be tricky for some as the magnetic catches are quite strong. Inside you will find a three metre attached lead with plug to suit the included regulator, a switch to select between 12 or 24 volts output, and a pretty blue led which may or may not be flashing – it seems to have a mind of its own.



    Hinging down from the back are “feet” which, when locked into place by wire supports, form a base so the unit can be angled toward the sun. These feet actually flex quite a bit which seems to cheapen the package a little – I guess the manufacturer could claim they act like shock absorbers but I think that would be from fault rather than design! The wire supports can be placed in different slots depending on the angle of the sun, however down here in Southern Australia you’ll run out of adjustment for at least part of the day. Putting something under the rear of the feet will help here (the box is about the right height). Another solution is to spin the whole unit 180 degrees and use the feet as support legs.



     Apart from the regulator, the package also includes a battery lead with colour coded spring clips, and both male & female cigarette lighter connection leads. These all use the same style plug at the regulator end, and while the connections are marked on the regulator, they could still plugged into the wrong input/output by accident. Some rudimentary instructions are also included.


     I was under no illusion that the unit may not perform up to the quoted specs, however, it is actually not too bad. Advertised output: 13W/ 17.5V/ 740mA. Easter Friday at camp was warm and sunny, ambient temperature about 25c. Unloaded the array was producing almost 25 volts, when connected to the battery this went down to a working voltage of 12.35 volts, charging at 0.74A (3/4 of an amp). Blocking the sunlight from one panel dropped the rate to about 0.4A and shading both sides lowered it further still, it was still charging at around 0.1A (100mA) though. Further testing at home returned similar results – well over half an amp in the autumn sun but still producing power in low light conditions.

    The panels used in this array are amorphous – they are not as efficient as mono or poly panels, however, they are cheaper to make, are not affected as much by high surface temperatures and are still able to supply usable electricity when it’s cloudy. It’s all a compromise though, a mono panel with the same area as the TopRaySolar unit would probably produce twice the power output (and charge your battery twice as fast) however they cost much more.



     The charge regulator is a Chinese number, similar to the cheapies seen on eBay. The specs rate it to handle 7amps – not sure I would hang a 100Watt panel off it though. It has flying connections for solar panel input, battery charge output and load output. As noted above, these all have the same style connector and if one wasn’t watching what they were doing could plug the wrong lead in.

    It has three LED's to indicate battery status – high voltage, low voltage & charging. There is some disparity with the specifications between what is written on the provided instruction sheet to that shown on the regulator itself; so, using an adjustable regulated DC power supply, I ran the regulator through its paces. It performed as it should with the following results:
Overcharge – cuts off solar input at 14.35 volts, reinstated when battery gets below 13.25 volts.
Undercharge – cuts off load output at 11.0 volts, reinstated when battery rises above 12.0 volts.

    11 volts is probably far too low for the regulator to cut out on a deep cycle battery, even if it’s under heavy load at the time. However, this doesn’t concern me too much as we don’t have an expensive deep cycle battery and we’re unlikely to flatten it to anywhere near that point anyway. With a bit of knowledge one could modify the regulator to cut out sooner, but then again if you are trying to protect a $300 battery you wouldn’t use a $20 regulator

    Here’s a look inside for those interested:



     While the screwdriver was out I pulled the bezel off the left hand panel of the array to check out the wiring. As suspected the 12/24 volt switch on the front just switches the two panels between parallel and series. In 12 volt mode the two panels are paralleled to produce more power (watts), while in 24 volt mode they are run in series to produce more voltage, obviously in this mode the array will only make half the claimed power (6.5 watts). I doubt we’ll ever need 24 volt output so I just may rewire it as an on/off switch.

    There is a blocking diode fitted to the negative output line to stop voltage returning back to the panel if left connected when there is little or no light. I’m guessing the blue LED is meant to stay on or flash depending on the array voltage (the instructions just say it’s a “charging indicator”), however, I think the internal circuitry is a little haywire as it just does what it wants, when it wants!

    As stated earlier, the attached lead is just three metres long. In our case, with where the battery is positioned, it’s just too short to be able to move the array around and catch sun all day. One of the CamperTrailers Group members generously gave me some heavy wiring from when he upgraded his own solar setup (thanks Paul!) I cut the existing lead near the array and fitted Anderson PowerPoles to both ends and then made an extension lead using the donated wire. The array can now be positioned up to 13 metres away from the battery/regulator with negligible voltage drop.



    I can see why one may want to use the included male cigarette lighter socket to power items, but I feel the female offering is redundant. I cut the cigar plug off and connected the regulator plug wire permanently into the trailer wiring. I still have more to do with the trailer wiring so for the moment the regulator is simply attached to the side of the battery with double sided tape.



    In conclusion; I’m very happy with the package, it does what we need it to do and the price was right. I would recommend it to anyone needing a low wattage panel & regulator (low voltage cutout issue aside) to keep their camper battery charged. There is also another version of this package which uses the same array but includes a battery pack instead of the regulator. It has cigarette lighter socket(s?), 5 volt USB outlets and a facility to connect another battery. I’m not sure on the capacity of the pack. One of our members purchased this setup at K-Mart a year or so ago.


 thanks to Dirk for sharing this info


april 2010