This project is a simple and cheap way to integrate renewable energy into your home by turning your appliances into solar electric hybrids. Here is how it works. A solar panel (or any other renewable power source) charges a storage battery. A control circuit continuously monitors the battery's voltage. When the battery is fully charged, the circuit automatically turns on a power inverter and switches the appliance from running on grid power to running on the energy stored in the battery. Then when the battery's voltage drops too low, the circuit automatically switches the appliance back to grid power until the battery is recharged.
This design doesn't require any modification to the appliance or your home's electrical system. It can work with any power source that is capable of charging a 12V battery (examples: wind turbines, bike generators, etc.). But most importantly the system is scalable. This design is set up for outputs of up to 75 watts, but by swapping out parts for ones with higher power ratings you can power larger appliances or multiple smaller appliances at the same time. This lets you build a system that fits your energy needs and your budget.
I am still trying to make improvements to the design. So if you have any questions, problems or suggestions please leave a comment. I would really appreciate the feedback.
Step 1: System Overview
Here are the five basic parts of this system:
1. 12V Solar Panel (or other renewable power source)
2. 12V Rechargeable Battery
3. Control Circuit
4. 12V Power Inverter
5. Automatic Switching Circuit
When assembled, the solar panel, battery, and inverter plug into the control circuit. The automatic switching circuit plugs into the inverter and the wall outlet. Then the appliance plugs into the automatic switching circuit.
The solar panel, battery, and inverter may be purchased off-the-shelf from a variety of locations. The last two parts of the system (the control circuit and the automatic switching circuit) will need to be constructed. This is detailed in later steps.