The simplest and easiest way to charge a battery with a solar panel is to connect the panel directly to the battery. Assuming the panel has a diode to prevent energy from flowing through it from the battery when there’s no sunlight. This is fairly common but not very efficient. [Debasish Dutta] has built a charge controller that addresses the inefficiencies of such a system though, and was able to implement maximum power point tracking using an Arduino.

Maximum power point tracking (MPPT) is a method that uses PWM and a special DC-DC converter to match the impedance of the solar panel to the battery. This means that more energy can be harvested from the panel than would otherwise be available. The circuit is placed in between the panel and the battery and regulates the output voltage of the panel so it matches the voltage on the battery more closely. [Debasish] reports that an efficiency gain of 30-40% can be made with this particular design.

This device has a few bells and whistles as well, including the ability to log data over WiFi, an LCD display to report the status of the panel, battery, and controller, and can charge USB devices. This would be a great addition to any solar installation, especially if you’ve built one into your truck.

This is [Debasish]’s second entry to The Hackaday Prize. We covered his first one a few days ago. That means only one thing: start a project and start documenting it on hackaday.io

Instructables user deba168 is an electrical engineer based in India. He posted a tutorial to solve a common problem in his country:

In India most of the people are living in rural area where national grid transmission line is not reached till now.The existing electric grids are not capable of supplying the electricity need to those poor people. So renewable energy sources (photo voltaic panels and wind-generators) are the best option I think. I know better about the pain of village life as I am also from that area. So I designed this DIY solar charge controller to help others as well as for my home.You can’t believe, my home made solar lighting system helps a lot during the recent Cyclone Phailin.

He then  made a charge controller  running on the Arduino Uno and with an important task: to protect the rechargeable battery of photovoltaic systems. It regulates the voltage and current coming from the solar panels and it’s placed between a solar panel and its battery . It is used to maintain the proper charging voltage on the batteries so as the input voltage from the solar panel rises, the charge controller regulates it,  preventing any over charging. It works on the principle of PWM which improves efficiency of the solar PV systems.

You can follow all the steps on his page but first take a look at the video: