We all take advantage of free solar lighting every day. Its called "daylight". But did you know the whole world runs on solar power one way or another. Even coal and petroleum originated from solar power millions of years ago. And even nuclear power comes from the remnants of dead stars! But with solar panels or solar powered lights and good batteries we can extend free lighting options well after dark. Many pieces of gear, like lanterns and other lights, are available with their own built in or attached solar panels, eliminating any installation issues.
Solar energy may be free, but the equipment to use it definitely isn't. Solar lanterns, solar battery chargers, and solar panels for boats and RVs will deliver lots of electrical power for free -- once you've made the initial investment in the technology. Solar appliances are usually somewhat more expensive to buy than their simple battery powered counterparts, but you'll save money on batteries. Also, you can recharge solar items anytime there is light so you don't need 12 volt or 120 volt power for recharging. Most solar powered lights use LEDs which means they use a lot less energy, making the solar charge last even longer.
Solar powered lanterns are becoming more readily available, more affordable, and more popular with campers. I often see solar lanterns around $10 each. Solar power means you don't have to carry messy or volatile, dangerous fuels, pack extra batteries, or run down your vehicle batteries to have adequate lighting in camp. Solar powered lanterns are especially handy for tent campers who won't have the luxury of 12 volt lighting of RVs but are still useful when camping in an RV. Solar powered chargers might even be powerful enough to recharge your cell phone or even your laptop. Some solar powered lanterns these days even have built-in USB ports to charge cell phones and other light usage devices. Solar powered lights are getting more and more affordable. You can even find them at dollar stores, usually in the form of pathway lights, but sometimes as little camping lanterns.
Solar panels are also becoming more common on RVs, collecting power to charge batteries during the day so you can use your RV lighting at night. With a large solar panel system, a massive battery bank,and an inverter you may even be able to run many 120 volt appliances without needing to fire up the generator. RV roofs are usually large enough to provide space for quite a lot of solar energy collecting surface. Even many boats have enough roof space on the cabin for solar panels -- and they are a lot less weight than a generator!
Solar powered "garden" or walkway lights can be used to mark tent pegs and guy ropes to prevent people from tripping over them in the dark. I've found small solar walkway lights at my local dollar store, so they don't have to be expensive. Sometimes you can adapt these small walkway lights for more general purposes like tent lighting. Remove the ground stake (it usually pulls out easily) and add a bail to hang it with or make a base for the spike on the light from an old coffee can or similar container filled with sand, rice, or beans.
Solar panels and the associated controllers and regulators for powering RV systems are still relatively expensive. A basic solar system for a boat or RV will likely cost $200-$300 plus installation. A system capable of routinely running significant 120 volt appliances will be far more expensive -- plus the extra batteries you'll need to store your free solar energy. An easy and inexpensive, though low power option, is a small solar panel that plugs into a vehicle cigarette lighter. They're usually around $20-$30. They are usually about twice the size of smartphone. They won't provide enough power to run appliances, but they are usually enough to maintain batteries while the RV is in storage when there is no load on the electrical system. They may be enough to recharge cell phones and other small battery powered appliances. They won't be able to keep up with power drain from lights or other 12-volt items in your RV.
Solar controllers may each have their own strengths and weaknesses. Compare the capabilities of controllers and try to match yours to your particular needs. The first controller I had with the solar panel on my boat supported keeping the battery charged even when the panel was under a green tarp over the winter. I upgraded to a newer panel with more features but using the same panel and the same battery and the same tarp my battery went dead in a few months. Haven't tried switching back yet as the new controller includes USB ports for charging our cell phones and it worked perfectly out on the lake.
Special solar battery chargers can be used to recharge any rechargable batteries. This is a very versatile option since it can be used to recharge replaceable batteries for lanterns, flashlights, and many other battery powered devices. For best results use only rechargeable batteries. Ordinary dry cell batteries are not designed to be recharged and attempting to do so may not be successful and may even be dangerous. Non-rechargeable batteries may swell, leak, or even explode when you try to recharge them. Fairly inexpensive solar powered chargers are also available to recharge cell phones, iPads, and notebook computers.
Solar powered lanterns are usually a little more costly than battery powered lanterns, but you will probably make up the difference fairly quickly in savings by not having to buy batteries again and again. Rechargeable lanterns don't need new batteries regularly but they do need an outside source of power (12 volt or 120 volt) for periodic recharging. With solar lights you will need to remember to put them out in direct light for a few hours every day to keep them charged. Leaving them your tent or in a cabinet or closet in your RV will be very disappointing. Sometimes the light inside a tent or vehicle is sufficient, but for faster and more complete charging, expose the solar panel to direct sunlight for several hours every day whenever possible. I have found solar powered camping lanterns for as little as $10 and even bought a couple of very small solar lanterns at Dollar Tree a while back. Some solar lanterns now include USB ports so you an use them to charge your cell phone too.
Because LEDs are far more efficient than incandescent bulbs, solar lights usually use LEDs. Incandescent bulbs have wattage ratings based on the resistance of the filament, which in turn determines how much light (and heat) they will produce. A 100 watt bulb will put out more light than a 60 watt bulb. Higher output for LED applications is usually created by using multiple LEDs, so a 17 LED lantern will be brighter than a 9 LED light. I have a 17 LED battery powered lantern it the shape of an old school kerosene lantern that provides pretty good general illumination for camping and for power outages at home. Unfortunately, it is not solar powered. It runs on 3 "D" cell batteries. The LEDs are so energy efficient that I once left the lantern on over night and it didn't run down the batteries. On the other hand, a guest once left a single incandescent 12-volt light on in the bathroom of my motorhome and the house batteries (two deep cycle 12-volt batteries) were completely drained in just an afternoon. Incandescent flashlights and lanterns that run on dry cell batteries will run the batteries down even faster. It makes sense. Think about it. An incandescent bulb is basically a dead short between the positive and negative poles of your battery. It is resistance creates light by super-heating the filament.
Keep your eye open for sales on solar lights. That is one way to help keep the cost down. I've often seen solar walkway lights in my local dollar store. These are perfect for marking tent pegs so you don't trip over them and with a little creative modification you can usually adapt them for more general use. One simple adaptation is to make a holder for them using an old coffee can or similar sized container. Make a hole in the top the size of the stake for the light, then fill the container with enough sand or other heavy material to hold the light securely. Another option is removing the pegs or stakes and fashioning some kind of hook or bail to hang the lights. I picked up a couple of small solar/LED lanterns at Family Dollar for $2 each. They are just the right size for tent lights -- about 4" tall a 3" in diameter.
Remember to put your solar lights and other solar appliances out in the direct sun to keep them charged. Some may get a little energy from artificial light sources, but for maximum benefit, put them in direct sunlight. A solar powered tent light is an ideal source of safe and economical illumination, but not if you leave it in the tent all the time!
Another handy solar application is a fan to cool the refrigerator coils. It is really nice to not have to worry about running the batteries down running the fan all the time. Since things generally cool off at night you don't have as much need of the fan when there is no sun to power it. Solar fridge fans come an a variety of sizes and prices. The larger, more expensive models cool better, but even a small fan improves air movement over the coils and helps to some extent. Basically, the more air you can move, the better it will cool the fridge. The most convenient ones I've seen have the fan and solar panel built into a replacement refrigerator roof vent making installation a snap.
Solar panels are becoming popular options for boondocking. About the only deterrent to using them is the rather high acquisition cost. A solar system sufficient to maintain RV batteries will set you back several hundred dollars, but once you have it, you get free, quiet energy from the sun to run your RV electrical appliances. Tie solar panels to a large battery bank and a high powered inverter and you can almost get by without running your on board generator. The size of solar panels makes them less appealing for tent camping but if you have the room to transport them you could make them work.
Solar panels are a particularly good fit for sailboats, allowing you to charge your batteries without the need for a generator, running the auxiliary engine, or connecting to shore power. Panels may be permanently mounted or installed on movable brackets so you can change alignment as needed to keep them aimed at the sun and move them out of the shadows of the sails. I used 45-wall panel on a fixed mount on the forward slope of the cabin on our sailboat and it generally got enough sun to keep the Group 24 12-volt marine deep cycle battery charged.
If you like to park in the shade, you won't get full capacity out of your solar panels. They work best in full sun and when oriented so they face the sun directly at right angles. Properly installed solar panels should be adjustable so you can face them directly toward the sun regardless of vehicle position. Portable solar panels allow you to put them just about anywhere and adjust the alignment as needed throughout the day. I was, however, surprised that my solar panels still working under the green farm tarp I put over my boat in the winter.
Light up for free!