How to Make Solar Power Units

Building a solar unit for the home is a lot more complicated than simply buying a solar panel and connecting it to your home. It involves multiple components, such as a battery, fuses, controllers, and possibly inverters. The entire system must be assembled into a unit that matches the requirements of whatever part of the home is going to be powered by them. However, with a little planning and an intrepid attitude, a home solar power unit can become a reality.

Things You'll Need

• Pen
• Paper
• Calculator (optional)
• Battery
• Solar panel(s)
• Screwdriver
• Wrench
• Cables
• Pocket knife
• Charge controller
• Fuse box and fuses
• Wire nuts
• Junction boxes (optional)
• Inverter(s) (optional)

Instructions

Select the Battery

1. Using a pad and pen, determine the needs of whatever you intend to power with the solar power unit. Determine what appliances will be in the system, how long they will be on and in use for a typical day, and the watts that will be consumed. For example, if you need to power lights with three 60 watt and one 100 watt light bulb for eight hours a day, you need to meet a total demand of 280 watts per hour, or 2240 watts.

2. Convert the watts to amps. To do this, you will need to know the voltage of the appliances in question. Using our light fixtures, which operate off of household outlets at 110 volts, the amps can be determined using the formula amps = watts/volts. So in this example, that is amps = 280/110, or 2.54 amps.

3. Select and buy a battery using the voltage and amp numbers that you determined in Step 2. Keep in mind that you do not want your battery to drop very far below a 50 percent charge during normal usage. This will extend the battery's lifetime. Therefore, choose a battery with double the minimum amps. Continuing this example, that would be a 110 volt, 5 amp battery.

Choose Your Solar Panels

1. Determine the voltage requirement of the solar panel. This needs to be a bit higher than the voltage of the battery, so pick a panel with an output of at least 115 volts. Many panels are made for use at household voltage, so panels like this should be easy to find.

2. Determine the power output that the panel needs to meet on a pad and paper. Your solar panel will need to meet the full 24 hour operating requirements of your solar unit during the estimated average of 6 hours of full sunlight each day. The example lighting unit will consume 343 watts for each of those 6 hours, so either a panel or group of panels must be assembled that will put out this much power per hour of full sun.

3. Purchase one or more solar panels using the figures determined in Step 2 and 3.

Building Your Unit

1. Set up the solar panels so that they are facing in a direction that gets them the most sunlight during the day. Follow instructions regarding the exact assembly of their support frame, but this will typically require little more than a screwdriver or wrench to drive the screws or bolts into place.

2. Establish the ground lead for every solar panel in the system. Your solar panel kit will have instructions for doing this, but typically it involves plugging a lead into the panel and planting it into the ground in a fashion similar to a lightning rod.

3. Plug in positive and negative cables that match the load you established for your system in Sections 1 and 2 into the solar panel(s). The format for these will depend on your panel, but most will follow one of two styles: 1) a plug-in cable; 2) a screw-fastened connector. The latter will require you to strip insulation from the end of a cable using a pocket knife, twist the bare wire around a screw, and then tighten the screw using a screwdriver.

4. Install the cables into a fuse box. Just like the solar panels, this will either be built so that the cables can be plugged in, or the box will use a screw-fastened connector. This is a key safety measure. It's better to lose a cheap fuse than an expensive solar panel, battery, or inverter.

5. Start a new pair of positive and negative cables, by plugging them into and then running out of the fuse box

6. Run the cables to your charge controller, and plug them in or connect them. The charge controller will prevent the overcharging of your battery.

7. Connect one set of positive and negative leads to the battery. Once again, the battery will either be set up with a plug outlet or wire connectors.

8. 

   Consider whether you need an inverter. Most appliances and devices are on Alternating Current (AC), but the electricity in your battery is Direct Current (DC). You can power light bulbs directly from the battery without an inverter, but that is about it. If you need an inverter, almost all use cables with plugs. Connect the inverter to the battery, using an adapter if necessary.

Tips & Warnings

• Try to choose your parts so that all the connector formats match. Having everything operate on the same plug-in format is very convenient. The worst system would be set up with multiple plug formats and wire connectors.

• Be sure that all devices are deactivated when you are working with the cables and wiring. If you have any doubts, disconnect the part of the system you are working with from a potential source of electricity.

Resources

• Tutorial: Charge Controllers for Solar Systems
• Solar Panel Inverters Explained