Updated on September 29th, 2020
Solar Power is quickly becoming the most popular choice for charging van batteries. It produces electricity whenever the sun is out, silently and without burning any fuel! Installation is also pretty easy! We did not originally plan to put solar power on the van but when we stumbled upon a great deal we quickly changed our minds! We are very glad we did.
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Van Solar Power Materials:
- Solar Panels–This is not the panels we original used as (probably for good reason) that company has gone out of business. We have these panels on the boat and love them.
- Solar Charge Controller–This is not the original budget charge controller we installed in our video. That one lasted less than a year. This is the replacement we installed.
- Roof Weatherproof Cover
- Solar Extension Cable
- MC4 Y Connector
Tools:
Panel Types
There are two common types of solar panels monocrystalline and polycrystalline, referring to the way the silicon is manufactured. The monocrystalline panels are made from silicon with a single crystalline structure, you can tell this by its even gray color. Polycrystalline panels are made up of (you guessed it) many different crystals in its structure. These panels look like a metal flake paint job. The monocrystalline panels are slightly smaller due to higher efficiency and less affected by heat, while polycrystalline panels are slightly less expensive. Both types can be used successfully and in the grand scheme of things it doesn’t make much difference. Use what fits your budget and the dimensions of your van.
Additionally, there are also two different styles of mounting, rigid and flexible. Rigid panels have a stiff aluminum frame around the outside and a piece of glass to cover the cells. Flexible panels have the cells sandwiched between two thin pieces of plastic.
Flexible panels are very easy to install. They can be glued or taped directly to the roof of your van and are very low profile. If you are looking for easy installation and plan on mounting them to a fixed surface these are a really good option. Keep in mind that the plastic used to cover the cells loses some transparency after a few years reduces the output of the panel. They will require replacement occasionally. Additionally, repeated flexing can eventually break the electrical connections within the panel.
The rigid panels are typically less expensive than flexible panels and can offer a much longer service life. However, rigid panels are much more fragile and require purchasing or fabricating brackets to mount them to the roof.
We went with two 100 watt monocrystalline rigid panels, because of the panel size and overall cost.
Mounting the Panels
You need to mount the panels securely to the roof of your van. You definitely do not want them to blow off on the highway!
Flexible panels are very easy to mount, using a sealant/adhesive or 3M VHB tape. Make sure you thoroughly clean the area first with acetone to remove any wax, dirt or oil before installing.
Rigid panels due to their size and weight need some sort of mechanical attachment to the roof. There are many different options to mount rigid panels. If you have a roof rack or a van with roof rails that accept a bolt or nut, it would make sense to mount them using Unistrut and/or some off the shelf brackets.
Our van doesn’t have any roof rails. Roof racks in our price range sit very high off the roof, so we decided to build our own brackets. We fabricated the brackets out of 3in x 3in x ⅛ in and 2in x 2in x ⅛ in aluminum angle iron we purchased at the hardware store. We used two different size brackets to compensate for the curvature of the roof getting the panels as close to horizontal as possible. Our brackets are mounted to the panels using 3/16 in pop rivets and to the van using ⅛ in self-tapping screws with a healthy amount of sealant between.
Van Solar Power Charge Controllers
There are two types of charge controllers used in vans, Pulse Width Modulation (PMW) or Maximum Power Point Tracking (MPPT). PWM charge controllers connect the solar panels to the batteries in a series of rapid pulses of different durations to reduce the panel voltage to the desired charge voltage. MPPT charge controllers use a DC to DC converter to control the charge voltage. The dc to dc converter allows the panels to run at a different voltage than the batteries (maximum power point) these charge controllers can produce approximately 20% more power than a PWM. This is especially true on cloudy or overcast days. Unfortunately these chargers are much more expensive than a PWM charge controllers. So much so that sometimes it makes more sense to install an additional panel rather than install a MPPT charge controller.
We went with a simple 20 amp PWM charge controller to go with our 200 watts of solar, but it lasted less than a year and we have since replaced it with Renology’s MPPT version.
Hooking Up Your Van Solar Power System
Once you have your panels mounted, you will need to wire the components together. First, you want to find a place to mount your charge controller, close to the batteries but still in a location you can occasionally access it. We found a nice place under our bed next to our fuse panel.
Battery Connections
Most solar charge controllers will be damaged if the battery is disconnected when the panels are connected or if the panels are connected first. For that reason it is best to directly connect your solar charge controller to the batteries through a dedicated fuse. You will want to use a large gauge wire to reduce voltage drop as much as possible.
We wired the battery side connections with 10 gauge, connecting directly to the battery side of our disconnect switch. This allows the charge controller to always be connected the battery if the switch is on or off. A 30 amp fuse close to the battery protects this wiring.
Solar Panel Connections
The way you wire your solar panels will depend on what type of controller you are using as well as the panel voltage.
PWM charge controllers need the panel voltage to be just above the battery voltage to allow them to charge the battery. Since most “12 volt” solar panels have a panel voltage of around 18 volts it is best to wire multiple panels together in parallel.
MPPT charge controllers with built in DC to DC converter can work with higher panel voltages created by series connections. That means you can connect your panels in series, parallel or a combination of both.
It’s important to note that when panels are wired in parallel the amperage is cumulative. Panels wired in series the voltage is cumulative.
The advantage of a series connection is simplified wiring and the ability to use a smaller gauge wire due to the lower amperage. Parallel connections have an advantage when it comes to shadowing, since each panel is essentially connected separately and doesn’t rely on other panels to complete the circuit. Shadowing will only affect that panel not the entire string of panels.
Most, if not all, panels nowadays come with MC4 type connectors they are a waterproof connector with a distinct male and female end, which allow you to connect panels together in series, parallels with Y connectors, and to extension cables that connect to your charge controller. It is not recommended to connect or disconnect them under load as they could be damaged. So either cover your panels or make your connections at dusk or night.
Since we have a PWM charge controller, we wired our solar panels in series using a Y connector with 6 ft extension cables running the wires down inside the van.
Wire entry
One tricky part of the installation is getting the wires into the van from the roof. You could drill a hole, shove the wire through it and try to seal it up with sealant and hope it doesn’t leak. A much better option is to use some sort wire entry box with a cable gland that mechanically seals around the wire and seals to the roof.
We used a clamshell type box and we also made sure to put grommets around the hole to cut down on possible wire chaffing. Screws and sealant attach the box to the van.
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