Solar Power

Lessen your carbon footprint and save on utility bills with solar power

Solar Power - Buying Guide

Utilizing solar power is an environmentally friendly way to power your home (or RV) while decreasing your electric bill. This guide provides an overview of solar panels for your home, and highlights their uses, advantages and accessories.

Solar Power Advantages and Benefits

Solar power is economical and clean with low maintenance requirements, offsetting what may seem to be prohibitive upfront costs.

  • The long-term savings and long life of solar panels, which can reach 25 years, make them worth the investment.
  • Power from sunlight is clean and infinitely renewable. The panels emit no fumes, have no greenhouse gases or carbon emissions, and are absolutely silent.
  • Solar panels for home use are self-sustaining and require almost no maintenance.

Grid vs. Off-Grid Solar Panels

Grid-tied solar systems reduce your total monthly bill from your electric company at your permanent residence or small business.

  • Solar equipment is installed on the roof of the home or business and the panels generate energy that is fed directly to the power company.
  • The power company credits the home or business owner for the energy on their electric bill, or the power fed back into the grid may cause your meter to run backward.
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Tip: This type of project requires a professional installer, licensed electrician and sometimes can require permits. To see if The Home Depot offers grid-tied solar power installation in your area, check our installation site or call 866-945-9211.

Off-grid solar systems provide power to a few devices such as a TV, radio, refrigerator or lights on RVs, boats or at remote locations with no access to electricity. Off-grid solar power set-ups can be installed by a typical DIY-er using solar panel kits without the need for a professional electrician.

  • Solar panels are installed on the RV, boat or cabin where they generate energy from the sun. 
  • The energy flows from the panels to a charge controller that regulates the amount of energy accepted into a battery. 
  • The battery can directly power devices that use DC power, or the power can be converted to AC power for other devices using an inverter.

solar diagram

How to Select Off-Grid Panels

Calculate your energy needs:

  • Identify which devices you want to power using solar energy.
  • Determine how many watts each device uses.
  • Decide how many hours per day you want to run each device.
  • Calculate how many watt hours per day each device will require. (Ex: 10W device x 3-hour run time = 30 watt hours)
  • Add all the watt hours from each device together for your total watt hours needed. (Ex: 30 watt hours for device A + 300 watt hours for device B = 330 total watt hours)

Check your battery:

Once you absorb solar energy through your solar panels, you will feed that energy into a battery that will then distribute power to your various devices. You must have a battery with a capacity large enough to handle your total watt hours. 

Tip: Most solar set-ups will need a 12- or 24-volt battery system.

  • Battery capacity is measured in ampere hours, which can be calculated as energy needs divided by battery voltage. (Energy needs / battery voltage = battery ampere hours)
  • Ex: To calculate the battery capacity of a 12V battery system with 490 total watt hours of energy needs: 490 / 12 = 40.8 ampere hours
  • Since batteries aren’t always 100 percent efficient, take 80 percent of the ampere hour number we just calculated: 40.8 x 0.80 = 32.6 ampere hours.
  • Make sure the battery you select is rated for at least, if not higher, the total ampere hours you calculated.

Choose your solar panel:

The number of hours of sunlight you receive depends on the time of year, as well as the location and position of the solar panel. Most solar panels typically receive at least four hours of sunlight a day, but this can be adjusted if you know the specifics of your environment.

  • To get the total power output of your solar panels, multiply the battery voltage and the battery ampere hours. (Ex: 12V x 40 ampere hours = 480 watt hours)
  • To find out how much power needs to be generated per hour, divide the total panel output you just calculated by the hours of sunlight available in a day. (Ex: 480 watt hours / 4 sunlight hours = 120 watts)
  • This gives you the wattage for the solar panel that will work best for you. In this example, you should look for 120-watt solar panel.

More on Solar Panel Components

  • Solar panels are the key to solar power. They are made up of photovoltaic cells that absorb the sun’s energy and convert it to electrical current. The three most popular types are polycrystalline, monocrystaline and amorphous.
  • Solar panels only generate power during daylight hours, and they do not store electricity. Off-grid power systems require deep-cell storage batteries to store the power for future use. The power stored in batteries can be called upon when the solar panels are not generating power.
  • Polycrystalline panels are made from a block of silicon with many different crystals. They are rigid, efficient and work great in areas with high levels of sun exposure.
  • Monocrystaline panels are made of one silicon crystal. They are more expensive but also more efficient.
  • Amourphous panels, also called thin-film panels, are flexible and easier to work with than the others. They work in all daylight conditions, making them ideal for areas with lower sun exposure.
  • Charge controllers, also known as charge regulators, regulate the voltage going into the battery and protect battery discharge at night. They also protect the battery as it can be damaged by the fluctuating charge if a panel is connected directly to it.
  • A power inverter converts DC power from the batteries to AC power, which is the common electricity found in homes. Inverters come in two types: modified sine wave and pure sine wave inverters.
    Pure sine wave power is the same power provided by utility companies, so everything in your home will function the same as it would under grid power.
  • Modified inverters are less expensive than pure inverters. Most home appliances will run using a modified inverter, but some common equipment should not run from a modified unit, such as laser printers, amplifiers, fans and CFL lights.
  • DC disconnects are essential in a grid-tied system but not needed in an off-grid system. The DC switch is installed near the point where the solar panel power enters the house. The switch turns off the power connection to the panels so you can safely work on them.
  • Batteries or a bank of batteries are required to store the power the panels create. Deep cycle batteries are designed to be discharged and recharged hundreds of times, making them compatible for use with solar panels.

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