Over the last year I have done a massive amount of research on how to power my devices and my business once I am living on the road. I have looked into many options, including gas generators, hydrogen, and of course solar power. I have pretty much settled on solar power and this post will discuss some of the reasons why as well as some of the negatives of it.
When I first started the search process I quickly discovered how much I had to learn and how much math was involved to do it right (well, unless you’re rich, in which case you can pay someone else to do it for you). I found that solar panels are expensive, and that the cheaper ones tended to be less efficient. The better the panel the more power a single panel will generate.
When it comes to shopping for solar panels the wattage at which they are rated really isn't the biggest factor; the amps generated per hour is far more important, because you will also need to figure out how many amp hours of power your devices will use a day. This will tell you how many amp hours you need to be able to recharge your battery bank each day. The battery bank is just a collection of deep cycle batteries which store the power (think: car battery) so you can use it when you want to. The amount of power your solar panels generate is directly related to your location and how much sun is available to you. For example, the sun is more intense in the desert of the Southwest than it would be in, say, New England.
To figure out how much power I need, I created a spreadsheet that plugged in the various data needed, including volts for something like a 110v house power outlet, watts - say 65 for something like a laptop. I then divided 110 by 65 to get 1.69: this means the laptop uses just under two amps of power per hour. Now lets say I think I will use the laptop 4 hours a day - that's 6.76 amp hours of power needed for this one item per day. I have to repeat this process for each thing I want to power. Let’s say the total power I will need is 100 amp hours a day. This means I need to have enough solar panels to generate this amount of power in 6 hours or less in my location. The panels are rated for their peak performance, which would be like high noon in middle of the desert during the summer.
Do your panels make enough power? Take the panel amps and multiply them by 6 hours. Let’s say you are looking at a 120-watt panel that generates 7 amps of power. That's 7x6, which is only 42 amp hours of power. That means 2 panels would be 84 amp hours and 3 panels would be 124 amp hours. Assuming you need 100 amp hours per day and the fact that you won't get peak charging from the panel, you would need 3 of the 120-watt panels, or bigger panels, or you would need to reduce the amount of power you are going to be using.
To make all this work you will need something called a charge controller and an inverter. The charge controller goes between the panels and the batteries. The charge controller’s job is to regulate the power from the panels to the batteries to prevent damaging the batteries as well as preventing the batteries from discharging power to the panels at night. An inverter is a device that converts the 12 volt d/c power from the panels and the batteries (same as the cigarette plug in your car) to 110 a/c power like what you have in your house. This is one place where wattage matters and it matters a lot. Inverters are based on wattage and you have to make sure the wattage is high enough to power what you need; on the flip side if it’s too large you could lose power from your batteries during the inverter conversion. For example, say you want to power a large microwave. You might need a 1200 - 1500-watt inverter. If you only have light duty needs - like powering a small laptop, a small LCD TV, charging a cell phone or camera - then you might only need a 500-watt inverter.
Getting yourself set up to use solar power can be a daunting task. My plan is to live out of my car and a small trailer. There will be no way to mount solar panels to the car’s roof. I found a solution in portable folding panels such as these <link> . This way I can just set them up on the ground or the top of a table or the roof of the trailer - then when I'm ready to go I just fold them up, store them and away I go. They are easy to set up: just unfold, point at the sun and clip to the batteries.
If you are looking to mount panels on top of an RV, it might be easier, safer and better to get the help of your local RV repair shop. I hope this post has helped you and I look forward to your comments.