Solar shed

From Builditwiki

How to create a solar powered shed

This was a very quick and easy project to add electricity to our shed. This really is a rechargeable battery powered system using the solar panel to recharge the battery.

Contents 1 Overview 2 Materials 3 Required Tools 4 Installation Steps 5 System Sizing

[edit] Overview

• Materials Cost: <$200
• Total Project Time: <1hr

The setup might seem complicated at first, but there a just a few components that are easily understood using the figure on the right:

1) The Solar Panel is the primary component (as you might have guessed). Shown here is the power line coming into the shed from the Solar Panel mounted on the roof.

2) The Charge Controller is the next component in the system. The charge controller serves three purposes, a) prevents overcharging; b) prevents reverse flow of power back to the solar panel; c) provides a status indication:

a) Since the solar panel is creating electricity whenever it is light out the battery could become overcharged without the charge controller.

b) When the solar panel is not creating electricity, it is important to make sure that the battery doesn't try to send electricity back to the solar panel. This would not only drain the battery, but could damage the solar panel.

c) The charge controller also indicates whether the battery is charging (green light), charged (yellow light), or not charging (no lights). These are the only indications provided by the inexpensive charge controller I chose for this project. More sophisticated charge controllers are available that will indicated the exact amount of electricity being generated. This is useful in a larger system.

3) The next component is the Battery. For this small application I chose a lawn tractor battery because it was adequate for my power needs and it was 1/2 the cost of a car battery which is a common choice. Larger batteries can be used and/or multiple batteries can be linked in larger applications. As stated above, this is a battery powered system, so battery selection is very important. Things to look for are "deep cycle" batteries and adequate "amp hours" for your application.

4) The Power Inverter is connected to the battery to convert the DC power to AC

5) The power inverter also houses the Power Receptacles and Power Switch. This is where the overhead light fixture is plugged in. The system is not electrified until the power switch is turned on

[edit] Materials

• Solar Panel (with mounting kit) - Solar Panel used in this project
• Charge Controller - Charge Controller used in this project
• Tractor Battery
• Power Inverter - Inverter Used in this project
• Fluorescent Light Fixture

• Caulk or Roofing Sealer
• Electrical Box
• Wire Nuts
• Electrical Tape
• Wood for shelf and mounting board

[edit] Required Tools

• Power Drill
  • Phillips Screwdriver Bit
  • 1/8" Drill Bit
  • 5/8" Drill Bit
• Step Ladder

• Safety Gear
  • Safety Glasses
  • Work Gloves
  • Hearing Protection
  • Long Pants
  • Work Boots (no open-toed shoes, at a minimum)

[edit] Installation Steps

Preparation:

1) Collect your tools & safety equipment

2) Equipment Site Selection - Exterior

• Decide where on the roof you want the panel to go. I selected the location to be close enough to the edge to run the wires to where I wanted the switch inside, and lined it up so one side would be screwed into a roof rafter.

3) Electrical components site selection - Interior

• Figure out where all the electrical components are going to be mounted (batter, inverter, etc.)

Attach Panel to Roof:

1) Locate screw locations

2) Pre-drill for screws

3) Dab caulk or roofing tar over holes

4) Screw Solar Panel frame to roof

5) Drill hole (under eave) to run wire inside

Wire up the Electricity:

1) Mount Electrical Components

• Most of the components have mounting brackets. I just mounted them to a plywood board mounted to the studs. I made a small shelf to hold the battery.

2) Wire it up.

• Attach all of the components as shown in the diagram above. I've just used alligator clips to connect to the battery, but you can use more permanent battery connectors.

3) Plug-it in and turn it on.

• Most of the inverters for small applications have standard 110V, 3-prong outlets so you can just plug in whatever you'd like to power (in this application, a fluorescent fixture) and flip the switch on the inverter.

Since the battery you buy will likely have charge in it, your system will not need to "charge up" before its first use. As stated in the summary, this is essentially a battery powered system with a solar recharger.

[edit] System Sizing

Electricity Primer

Watts = Volts * Amps

Solar Panel - How long to recharge

Battery - How much Power

Inverter - How much power you can use (aka how much stuff can you plug into it)

• If you want to run more stuff (bigger tools, more lights, etc.), you'll need a larger inverter. You can't suck power out of the battery any faster than the rating of the inverter.
• If you want to run for longer time, you'll need a bigger battery (or more batteries tied together). How long you have power depends on the size of the battery.
• If you need to recharge the battery faster, you'll need a bigger solar panel (or more panels tied together).

Consider the following scenario:

On the weekends, you would like to run a few small power tools for between 1 to 3 hours, but don't need any power during the week. You'll need an inverter to match the power draw of your beefiest power tool. With 3 hours of near continuous use you would likely suck all the power out of ~3 car batteries (this is a total guess, you'd need to check the Amp-hour rating of the batteries you buy and do a little bit of arethmetic). But since you have all week to recharge, you'll only need one or two small solar panels to recharge the batteries.