How to Install a Solar Panel

Never worry about whether your boat's batteries are charged again.

I had decided to put a solar panel on my Lance camper and ordered a 150-watt solar panel from Renogy. When it arrived, I discovered it was too big for its intended location. Return shipping was more than I wanted to pay, so I decided to keep it for a future project. Little did I know that the project idea would come to me the next time I took my boat to the ramp.

As I backed the boat down the ramp, a sickening feeling came over me: I had not charged my batteries the night before. At the time I had a pair of older marine batteries, and sure enough, as I turned the key the motor struggled to crank. I had a jump box — it also hadn’t been charged in a while — on the boat, and it barely provided enough supplemental power to turn it over, but I got the boat started. I then sat at the dock for 15 minutes and allowed the motor to charge the batteries, so they would turn the motor over again if I needed to cut off the motor and restart it. While sitting there watching everyone else head to the fishing grounds, I decided what to do with the 150-watt solar panel.

At home I measured the space I had available on the hardtop of my 2004 Pro-Line 25 walk-around: plenty. I have a 300 hp Evinrude E-TEC G2 with digital gauges, a Garmin chartplotter and radar, and two marine VHF radios. I also have a JBL stereo with Kenwood speakers and a subwoofer in addition to the normal pumps, lights and equipment. My power requirements are about average, and I’m sure some of the electronics have a parasitic draw on my batteries when it’s parked, which is why I always had to charge the batteries. I have since replaced the batteries with Optima Blue Top Marine batteries and wanted to keep them charged without having to think about it.

My boat has a 12v system. Solar panels can also be used for 24v and 36v systems. The wiring is different, though, and the solar panel manufacturer’s instructions should be followed to wire these configurations.

Here are the materials I needed to complete my project:
• Solar panel(s). Measure the space and order the biggest panel that will fit the space. Keep in mind any future upgrades — outriggers, radar, etc. — and plan accordingly. I used a Renogy 150-watt Monocrystalline Photovoltic (PV) Solar Panel.
• Solar panel regulator/charge adapter. This keeps the solar panel from overcharging the batteries. I used a Renogy 30-amp PWM charge controller with an LCD display.
• Solar panel mounting brackets (if they don’t come with the panel). Be sure they’re appropriate to where the panel is being mounted.
• Wire. You’ll need enough to run from the charge controller to the batteries and then from the solar panel to the charge controller. How much will depend on how long the wire run is from the controller to the battery and from the panel to the controller. Calculators on the internet will help determine what size (AWG/gauge) wire is needed for the required lengths. I have the controller installed in the overhead cabinet in my hardtop, so I used a 10-foot 12 AWG adaptor kit from Renogy that plugged directly into the panel.
• In-line maxi fuse holder (2).
• Heat shrink butt connectors (4).
• 30-amp maxi blade fuse (2).

Once you have decided where to put the solar panel and checked to ensure the mounting bracket screws will not penetrate any wires or critical components, mount the solar panel. Keep the panel covered with a piece of the cardboard shipping box, because it will produce electricity as soon as the sun hits it.

Find the location for the solar charge controller, which should be as close to the batteries as possible, for the least amount of power loss. The area should stay as dry as possible. Again, ensure the installed screws won’t damage anything.

Using the appropriate wire size, based on the length of the run, connect the negative terminal of the battery to the negative battery input terminal on the charge controller.

If you are going to use an inline fuse, connect it to the wire being used for the positive battery to controller wire. Use heat shrink butt connectors and connect the positive terminal of the battery and the positive input terminal of the charge controller. Insert the fuse, and the charger will provide a reading of the current status of the batteries.

Now, to the solar panel. Connect the negative wire from the solar panel to the negative input on the charge controller.

I recommend an inline fuse on the positive wire from the solar panel to the positive terminal to the charge controller (use heat shrink butt connectors). Insert the fuse.

Finally, remove the cardboard or whatever was covering the panel, and it will immediately start charging the batteries. The strength of the charge will depend on the amount of sunlight. Clouds and time of day will affect how much power the panels will produce.

Enjoy never having to remember to plug in your charger or worry about your batteries going dead when you’re out on the water playing your radio or running your electronics.


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