How Do Solar AC Systems Work?

Guest Post by Kayla Matthews

If you're interested in keeping your home cool while being more reliant on renewable energy, a solar air-conditioning (AC) system could be a smart choice for helping you save money, enjoying more energy efficiency and adopting a more eco-friendly mindset. There are three main types of solar energy systems:

• Photovoltaic-based — Energy collected from solar panels powers an air-conditioning unit or a central heating and cooling system.
• Solar thermal — The sun's energy cools the home through a heat pump. Unlike photovoltaic systems, solar thermal ones don't generate electricity.
• Passive cooling — These systems only partially use the sun for cooling. They incorporate strategies such as landscaping and insulation to keep a home cooler. Although you may come across information about passive cooling, this article won't focus on it.

Options known as hybrid systems rely on small amounts of non-solar energy to operate. They combine photovoltaic panels with electricity. Hybrid systems also switch back and forth between solar power and battery power. During a sunny day, the light charges the batteries for later use. When there's not enough sunlight, electricity charges the battery backup system.

There are also solar-powered absorption chillers, also known as evaporative coolers. These systems function when the chillers use fans to blow air over water-saturated materials. The fans and their required motors get their energy from the sun.

All air conditioners work when a compressor — located inside a condenser — pressurizes the refrigerant. A solar-based system creates that pressure by using heat from the sun.

As the refrigerant gets warmer, the compressor doesn't need to work as hard to make the cooling process occur. As such, solar AC systems can aid in meeting energy-efficiency goals. Evaporating refrigerant in a solar thermal system gets pumped through coils, absorbing heat and moisture.

Room-based vs. whole-house solar AC systems

People who are feeling more confident about cooling their homes with solar power after reading the information above should also decide whether they want to use a solar-based AC system for a single room or an entire house. Keep in mind that, if you're using solar panels, a centralized system for your abode will require more of them than if you use a window unit.

Companies are also developing portable solar-power air conditioners, such as the Coolala. That brand had a successful Kickstarter campaign, and the product looks like a small guitar amplifier. It has wheels for easy portability and weighs only seven pounds.

A man who lives in a tiny house decided to invest in a mini-split solar AC system and get a professional installer to set it up. After the installation, he decided to stress-test the AC and see how long it'd take for the batteries in the system to dip below 50 percent power. At the end of nearly three days, they still hadn't reached that point, so he ended the test after deciding he'd investigated enough.

When you're attempting to work out the number of solar panels required to cool your whole house, several factors come into play. Your intended usage matters, along with the average amount of sunlight your area receives.

People who are still feeling unsure about some aspects of solar AC may want to start with a portable or single-room unit first. Then, if those results are at least as good as expected, you might want to think about scaling up. No matter the scale of a solar-based system, it'll function through one of the options described in the previous section.

Professionals may need tech training

Heating, ventilation and AC (HVAC) professionals come to homes and commercial settings and install or repair systems to keep the environment comfortably warm or cool, depending on the season. According to statistics, there should be a 14 percent increase in HVAC mechanics and installers from 2014 to 2024.

Solar air conditioning is one of many emerging options that enable people to keep buildings comfortable, while being mindful of sustainability. Although there are no substantial differences between how solar ACs and conventional ones work, it's useful for HVAC professionals to consider upgrading their skills by doing learning modules that specifically relate to solar cooling.

HVAC professionals should also prepare to engage with their clients about how solar air conditioners can help meet relatively specific needs beyond the general cooling of a building. In one example, an Irish gas station used a solar thermal system on the HVAC equipment used to cool refrigerated cases. This retrofitting project achieved 41.5 percent average daily energy savings compared to the energy required before the solar installation.

There were at least 1,200 solar thermal installations used for cooling in 2017. That amount is more than 10 times the 2007 numbers. As more individuals and businesses get interested in what's possible, HVAC professionals must be ready to answer their questions.

Ongoing developments related to cooling technologies may soon affect how photovoltaic cooling systems work, too. In one recent example, scientists developed a new silica-based material comprised of tiny spheres. It can cool down a surface such as a solar panel without requiring additional energy expenditures. Moreover, the team noted that the material could remove half the heat a solar panel absorbs on a typical clear day, increasing the panel's efficiency by 8 percent.

Options worth exploring

If you're ready to move beyond conventional ways of cooling your home and see what solar panels can do, the possibilities are enticing. It's best to do thorough research regarding your specific system to determine which choices are most appropriate. If an active cooling system isn't the right option for now, passive cooling, as briefly described earlier, could help.

Kayla Matthews is a tech journalist who has written for sites such as TechnoBuffalo, MakeUseOf, and Mother Earth News. To see more tech stories by Kayla, visit Productivity Bytes or follow her on Twitter.