Solar vs. geothermal energy: Which is right for you?

Like solar energy, geothermal energy is a renewable source of power that can be installed for residential use. However, the two technologies differ in what they are capable of doing and who they are best suited for. Read on to learn how geothermal energy works, along with the similarities and differences between solar vs. geothermal.

At the largest scales, solar and geothermal techniques can be used to generate clean, renewable electricity. However, for most residential and commercial property owners, geothermal energy can only be used as a heating and cooling solution, while solar energy can generate electricity with photovoltaic (PV) technology. For anyone looking to save money on electricity bills, installing solar energy is the way to go. You can use a residential geothermal energy system for your home climate needs, but it will not produce electricity to run all of your appliances like a solar energy system.

Heat trapped deep in the center of the earth radiates outward towards the planet's surface slowly over time. The center of the earth is similar in temperature to the sun's surface, and as some of that heat escapes outward, you can harness it for energy.

There are two main ways you can capture and use geothermal energy: power plants and heat pumps. Geothermal power plants are massive systems that are mainly installed and operated by utilities. Power plants involve drilling wells several miles deep into the earth where temperatures are very high. Steam produced by underground water reservoirs at these great depths is brought to the earth's surface where it spins turbines that generate electricity.

A geothermal heat pump necessitates drilling a well, but only for a few feet below the earth's surface instead of a few miles. At these depths, the temperature in the ground is constant, somewhere around 50°F. During warm months the ground temperature is cooler than the air, and fluid can be cycled through pipes in the ground to transfer heat from your home into the surrounding earth. The reverse process occurs in colder months when the air is colder than the ground: fluid is cycled through the geothermal system and captures heat from the ground to then be dispersed into your home.

Geothermal energy can't be used to offset electricity use, but in some cases, it can be a worthwhile renewable energy option that will save you money on heating and air conditioning in the long term.

For example, if your home has a small roof that can't fit that many solar panels consider a geothermal setup for your heating and cooling needs. You could still install a small solar array to cover the majority of your electricity needs aside from heating and cooling and use geothermal energy for climate control alongside solar.

Another situation where installing a geothermal energy system makes sense is if you live in a region with an especially cloudy climate. Installing enough solar capacity on your property to offset the energy needed to run an electric climate control system can be difficult if, for most of the year, your panels aren't receiving lots of sunlight. Solar panels still produce energy when it's cloudy, but not at their full capacity.

Geothermal heating is not an appropriate solution for every property. For example, if you live in or near a city, you may not be allowed to dig deep enough into the ground to support a geothermal system. High upfront system costs may also be prohibitive, especially because, unlike solar, geothermal systems can't do anything besides home climate control.

Luckily, you don't need to install a geothermal energy system in order to power your home heating and air conditioning with renewable energy. By pairing an electric climate control system like air source heat pumps (ASHP) with a solar energy system, you can run your heating and AC entirely on electricity generated from the sun.

If you're interested in offsetting your electricity use with solar energy, the best way to find the right installation for you is to register on the EnergySage Solar Marketplace to begin comparing competitive solar quotes from qualified local solar installers. Curious about installing an electric heater (like an air source heat pump)? You can leave a note in your property profile noting your interest and solar installers will know to design a solar energy system that can cover the energy use of an electric climate control setup in addition to your regular electricity use.