Experiments with Flexible PV

A while back, my wife and I were looking for a light source that would be bright enough to read by, would be battery-powered that of course could be recharged. We found a Coleman lantern that lights an 11 watt florescent bulb and runs on a 4 amp/hour lead-acid battery. This works pretty well, although it is barely light enough to read by (you need to lean into the light) and it tends to run through the battery fairly quickly (about 4 – 6 hours). That being said, it is an excellent back-up lighting source for when the power goes out, and when we took it camping it was a perfect light for the tent.

So, how do you recharge such a small battery? Well, Coleman gives you a standard wall adaptor that will charge the battery in about 18 hours on the grid. I can tell you that it is a very inefficient charger in that it produces a lot of heat and therefore is wasting power. They also give you a standard cigarette adapter so it can be charged off the car’s battery. This meant possibly draining the car’s battery or running the car (burning fuel) to keep the battery from being drained. It seemed to me that I had to be able to recharge this battery off the sun using PV. My first thought was my recently build small PV system which I was using to charge batteries. The problem was that the lantern had such a small battery that the charge controller couldn’t properly charge it. I was discouraged, but not giving up. On the web, I found lots of small wattage PV panels that would have probably done the job, but what I ended up with was a flexible (rollable) PV panel made by PowerFilm. This small panels produces just over 1 amp of power but is flexible enough to be rolled up, draped over anything (including a tent), but tough enough that it can be left out in the rain. The material it is made out of is very much like a tarp, and I can see it being used as an awning for a tent, or simply draped over anything that needs power. To me this is the perfect panel for taking camping, or on the road with you to keep any battery powered device charged up such as your cell phone, iPod, portable computer etc. Now, that being said, you need adaptors for all of those devices, but that doesn’t reduce the usefulness of this panel.

For the lantern, I ended up running a couple wires directly to the battery so that I could hook up the panel through a small charge controller. It worked perfectly, and now on a nice sunny day, I can get this lantern fully charged without using any grid power, or running down the battery on the car. I am definitely looking at getting the adapter for this panel that will allow me to charge our cell phones and other small batteries since these are other things that we could easily take off grid.

So, next time you think of small-scale PV, don’t always think of those ridged large panels you see on peoples roofs, think about the newer flexible panels that have many, many uses for small PV projects. Then again, this is just life according to Troy.