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How to Make a Solar Panel Emergency Backup System

I have had fun building several small homes and would love to share some of the things I've learned with readers.

This easy-to-build emergency backup solar power system can charge your vehicle battery or storage batteries in the event of a power failure.

This easy-to-build emergency backup solar power system can charge your vehicle battery or storage batteries in the event of a power failure.

DIY 200-Watt Solar Panel Battery Charger System

Recent natural disasters have shown us that the power grid that we rely on is vulnerable to large-scale disruptions. If the power were to go out in your neighborhood for an extended period of time, how would you charge the electronic devices that you rely on?

A solar panel battery charging station is one easy way to keep backup power on hand without having to worry about running a gas generator.

For my own home and RV, I made this simple, easy-to-build 200-watt solar panel battery charger system to keep a deep cycle battery in my shop charged, as well as to take along in the RV. It is capable of charging large 12-volt batteries and even topping car and truck batteries with more than 10 amps of power when the sun is shining.

After a storm, you can use a setup like this to keep your car battery topped off (provided there is some sunlight) so that you can recharge cell phones and other electronics.

This setup can be created in 3 simple steps:

  1. Create a 200-watt solar panel foldable array
  2. Attach the battery leads and charge controller
  3. Set the charge controller and connect your solar battery charger
Drill a 1/2 hole in the side of the panel so that you can attach a lock and cable to prevent theft.

Drill a 1/2 hole in the side of the panel so that you can attach a lock and cable to prevent theft.

Step 1. Create a 200-Watt Solar Panel Foldable Array

The first step is to purchase two 100-watt solar panels and a connecting kit. The panels that I chose are made by Renogy and are rated at 100 watts and 5.4 amps.

The wiring harness to combine two panels, 20' of lead wire, and the hinges cost just under $200. The charge controller, which helps charge batteries safely and more efficiently, cost around $40.

Using self-tapping metal screws, which are available in the hardware aisle at Home Depot or Lowes, attach two metal hinges along the edge of the solar panels so that they are connected. Attach the hinges so that the panels can fold together, with the solar panels exposed and wires protected inside of the folded pair. This makes the DIY emergency battery charger easy to transport.

Next, drill a 1/2-inch hole in the side of one of the panels. This is to place a lock in, so that you can attach an anti-theft cable to the panels.

Next, attach the wiring harness and combine the two panels. You can secure the wire and wiring harness to the panels using zip ties.

Attach the battery leads and charge controller to the solar panels.

Attach the battery leads and charge controller to the solar panels.

Step 2. Attach the Battery Leads and Charge Controller

Next, attach the battery leads and solar panel lead wires, which are also available for sale with many 100 watt solar panels. Because energy at 12 to 14 volts is easily lost over long lengths of wire, you will want to keep the lead wires as short as possible, yet long enough for you to re-position your panels to keep them in constant sunlight and to reach your battery.

In my case, I chose to keep my solar panel leads at 20', which does result in some energy loss but also enables me to place the panel outside of my garage and charge my vehicle's battery inside.

The battery leads themselves, which run from the charge controller to your battery, might be around 4' or less. Make sure that you connect the red lead to the charge controller's positive output terminal and the black to the controller's negative terminal. I used a 14-gauge stranded lamp cord in this setup, but a larger wire of 8 to 10 gauge would be preferable.

You may want to install some quick-disconnect "alligator clips" like those seen in the photo above. This allows you to easily connect your emergency solar battery charger to any 12-volt battery.

Step 3. Set the Charge Controller and Connect Your Solar Battery Charger

You will want to familiarize yourself with your solar charge controller. Most solar charge controllers are able to be customized to individual needs and battery types. Read your solar charger's manual and adjust the settings for the type of battery that you will be charging. My own charger is set to begin charging when the voltage in my battery falls below 12.5 volts.

Next, carefully connect the charger to your battery. Before placing the solar array in the sun, connect the positive (red) alligator clip to the terminal on your car, RV, or storage battery's positive terminal. The positive terminal is marked with a "+" sign.

Next, clamp the negative (black) clip onto the frame of your vehicle—perhaps onto a bolt that's on your car's frame—as far from your battery as the lead will allow. This is so that any small spark that may occur does so on the negative or black alligator clip, far away from your battery. Sparks can cause some car and RV batteries to explode, so make sure that you follow this procedure carefully.

Next, you will want to place your solar panel battery charger array into the sun, away from the shade of trees or your home. Direct sun is the best for charging batteries, so make sure that you angle the whole panel so that it faces the sun as directly as possible. You may have to keep moving the solar panels throughout the day so that you keep the charge output at maximum.

Project Cost and Utility

My all-in cost for this DIY solar battery charging station was $250. It has proven to be invaluable on a couple of occasions. On one occasion, we lost power from the grid for more than two days during an ice storm. The solar charger was able to keep our SUV's batteries charged up so that we could use the vehicle as our phone and tablet charging station. We even charged our flashlights, which are rechargeable by USB cord.

On other occasions, we have used the DIY solar charger on our RV for remote camping. It has provided ample power to charge our deep-cycle RV batteries so that we can run our lights and 12-volt fans at night for comfort.

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This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2020 Nolen Hart


Danny from India on August 28, 2020:

Doodlebugs, this is really helpful especially in countries where electricity rates are exorbitant. Love this piece, thanks, Sir.

Peggy Woods from Houston, Texas on August 28, 2020:

Being able to run a fan and lights during a power outage and recharge batteries make this project of yours one to replicate for all the do-it-yourself people out there. I would imagine that yours is less expensive than the ones ready-made.