This article is aimed at van/RV use of solar panels, combined with a Goal Zero. There are other units similar to GZ, and this info works if you want to build your own instead of buying ready made.
By David Rosner | Images by Farm League
The success of Goal Zero’s En Route Series has profiled many of the individuals who have decided to power an off grid lifestyle with solar based products. The growing “office anywhere” mentality has boomed tremendously over the past few years. At GZ, we’ve seen this materialize in the numbers of those outfitting RVs, vans, and multitudes of other vehicles, for both vacation and permanent residence. Here’s how they did it. Always remember, when in doubt, consult a professional.
PLAN IT OUT:
First, as with all solar projects, figure out how much power you think you will consume and work backwards. Try to avoid using air conditioners, heaters, microwaves, and blenders to greatly reduce your needs. Any product label will tell you how much power it needs, usually over the course of an hour. Determine your AC vs. DC needs (types of electricity) to know inverter size (turns battery power into a wall plug) and battery capacity. Always round up and try to decide if you plan to expand your needs, remember that batteries will live longer if you don’t fully drain it with every use.
When running off solar and batteries it is common to calculate usage over 3 days. Believe it or not, the sun doesn’t shine every day! Many compromise and know that when it’s raining, conserve. The size of your solar array and charge controller will need to be able to recharge your batteries in a timely manner, whether that is the next day or a few weeks from now. Find the physical size of the components you plan to use to determine what space you will need for your system with venting as a consideration. Now is a great time to mention that Goal Zero products like the Yeti are all-in-one. They include a charge controller, inverter, voltage regulators, protections/fusing, and a battery, so if it fits your needs, it’s a great solution that can even provide portability away from the vehicle if need be.
-you think you’ll use about 500watts/day, 1500 watts over 3 days. Get a 100Ahr battery (12V*100Ahr=1200W). Chain an extra battery to grow capacity if it’s not enough.
-Solar- panel rating*.75*4 (true sun hours)=how much solar you will produce in one day- ish.
Example: 100W solar panel*.75*4= about 300watts/day solar production
Examine the roof of your vehicle to see how flat, how much space, and what material you are working with. The fewer penetrations you make, the fewer leaks you might have. If a flat, solid structure, you can actually think about using tape… yes, tape. Industrial tapes like 3M’s VHB #4950 has a tensile strength of over 100 lbs./in^2, which over 4 mounting feet give more than enough strength. Upon adhesion, it also creates a weatherproof bond, WIN WIN! If you are hesitant on tape, or enjoy driving over speed bumps to get air, feel free to use a screw that won’t rust on you and make sure to add enough weatherproofing sealant to prevent any leaking.
When deciding on location, consider where you want the solar cable to enter the vehicle. There are sometimes vents that work; otherwise roof or cable glands will be necessary. Try to place these under the solar panel if possible for extra weather protection, but a liberal amount of sealant will always do you good. Yes, this means that more than likely you will need to drill a hole in your roof. Also try to align this with workable space on the inside, and the closer to the rest of your system the better (less wiring). For any premade cables, you might need to cut off the end so it fits through a smaller gland and splice it on once through the other side. Lastly, consider the thickness of your roof, how much insulation is between layers? This could be a bigger space than a cable gland, so choose your cable feeding and strain relief device carefully. We’ve seen everything from sprinkler tubing to Chase Nipples, anything built to act as a bulkhead connector (so maybe not so carefully).
-Consider connecting your system to your alternator to charge as you go. Just make sure to use an isolator so you don’t drain your starting battery.
-Drive with your panels flat for safety. Tilting your panels to optimize the angle can add a significant amount of power throughout the day. Also, pointing your panels at the sun throughout the day, even if you have to rotate your vehicle, can also make a noticeable difference.
-Remember that refrigerators vary greatly on the power they use depending on what’s inside, how often you open the door, what settings you use, and ambient temperature. Hedge your bets on all these factors to reduce power consumption.
-Remember that solar panels need to be in the sun… duh! But having panels connected to your roof means that your vehicle also has to be in the sun. Will the extra heat in your vehicle be tolerable, especially without an AC unit? Pulling out solar panels upon arrival can be a great compromise.
-Of course, gas generators do have a viable place in the RV world, just not in RV parks after 10pm. They are great at charging batteries while you use them to power your AC units so you don’t waste extra energy!
-Solar panels lose efficiency the hotter they get, and batteries lose efficiency the colder they get.