Experimental Electric Vehicles

October 30, 2009

A Bright Idea

Filed under: 1 — tonyhelms @ 2:11 am

While tinkering around the garage and pondering new energy saving concepts I found a fairly inexpensive, easy to make, and rather efficient solar charging system.

Use solar power to recharge Dewalt tool batteries and “AA” -“D” size cells for many applications.


Find inexpensive solar panels and charging equipment and test the efficiency, durability, and practicality of home solar energy usage.

Assembly of experiment:

I started where I knew inexpensive yet efficient solar panels are readily available, Harbor freight. I did some research on their website first to find the best choice of each component needed. Here is a list of the items I used, all were purchased at Harbor freight

12″x36″ 15 watt 12V Amorphous crystal solar panel-$70

7amp Solar charge regulator-$30

200W DC/AC converter-$25

12volt state of charge indicator -$5

Werker 12v 55AH deep cycle battery- Free (well a left over from a previous EV I made, it was originally $70)

It starts with the solar panel, mounted in such a way that it will capture the light from 11:00AM to 3:00PM. These are the most powerful rays of the sun and will produce the most energy.

Here is how the solar system is wired, the Panel is connected to the regulator, the regulator then charges the 12volt battery. The regulator is then wired to the inverter that converts the 12volt DC battery to 110v AC power. This now me to run any 200watt household appliance on this outlet, items such as, chargers, computers, radios, small TV’s, etc. The regulator is necessary because during times of darkness the regulator prevents the battery from discharging into the solar panel, also the panel in intense sunlight can produce more then 12 volts, the regulator reduces it to back down to properly charge the battery.

Wire schematic

Panel mounted on roof of barn

On top is the solar charge regulator, the battery sits in the corner and the inverter next to the battery, attached to the battery is the state of charge indicator.

I decided to add this small state of charge indicator to monitor the battery during charge and discharge cycles. It only activates when the small button is depressed, therefore will not become a parasitic drain on the battery.

Now look at all the batteries i have charged with free and clean solar energy!

During cloudy weather the solar panel will generate upwards of 20 volts and 1.9A! This is very good epically good considering that I have not done any intense sun tests yet. the system works flawlessly and has plenty of power to supply the chargers. An important thing to note, I placed the panel close to the edge of the roof so that leafs and snow can be scraped off easily with a foam snow brush.

Solar energy is very viable and should be used more, the only disadvantages are things that block the light, leaves, snow, or things that could break the panel such as hail, branches, or golf balls. But the advantages are vast, a clean, quiet, and efficient method of using free light energy to help save electrical energy. Another big advantage is if the electrical grid ever fails your solar power will be a reliable, efficient, and long lasting source of power that will long out live any gasoline generator, remember gasoline is pumped from the tanks and ground using ELECTRICAL power. Solar power is a very practical, efficient, and most direct method of making electricity, and hope to see more of it in the future.

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