Catch Some Rays: Is Solar Power Viable at Home Yet?

Soaking up the sun does wonders. After all, one large tree can lift 100 gallons of water straight up its trunk in a single day, just by sitting pretty and getting its share of the sun’s energy (thank you, photosynthesis!). “Imagine the din of commotion, the clutter of machinery, that would be needed for a fire department to raise a similar volume of water,” marveled Bill Bryson in A Walk in the Woods. With such inspiration in nature, it’s really no wonder people have been clamoring to harness the sun for our energy needs, too.

But is the technology still too new to make it practical for homeowners?

“People think it’s so far away; that the technology is not there yet. That’s a myth,” states Dick Co, PhD, managing director of the Solar Fuels Institute and environmental chemistry professor and director of outreach and operations at Argonne-Northwestern Solar Energy Research (ANSER) Center.

Basking in Benefits

Let’s talk numbers. Right now the world’s population uses about 16 trillion watts, or 16 terawatts, of energy per year. Meanwhile, each year the sun puts about 120,000 terawatts on the earth, according the U.S. Department of Energy. This makes the sun the biggest potential source of power around. “In about an hour we get all the power in the sun we need to run all of civilization for a year,” says Co.

“There is plenty of solar power in the U.S. to supply our electricity needs,” if we were to build the infrastructure to capture it, confirms George Crabtree, PhD, of Argonne National Laboratories and University of Illinois at Chicago. However, most scientists also believe that solar alone will not solve all of our energy problems. It will likely be one of the many solutions in our clean energy portfolio.

In addition to sheer bounty, here are a few other pros to solar once it’s set up:

  • No transport of raw materials needed—trucks and trains (as in shipping coal to power plants) are way less efficient than a good ol’ fashioned ray of sunshine.
  • Minimal harmful waste or byproduct once it’s up and running; the manufacturing and shipping of the panels do have an environmental impact and require energy (from carbon-based fossil fuels today), but the energy used to make the panels can be recovered in just a few years.
  • It’ll last to infinity and beyond! Unlike carbon-based fuels, this is so not a finite resource—a good thing since Co points out global energy needs are projected to double in the next 40 years.
  • Going solar may increase the value of your home (here’s a little more on that from Forbes).

Making Solar Practical

In many cases, solar power can be used to provide at least a portion of the energy needs for your home. Currently this hot commodity is available for homes in a few main ways:

  • Passive solar home design: Designing the home with strategically placed windows and heat-absorbing floors and walls to absorb heat during day and give off heat at night.
  • Solar photovoltaic (PV) cells: Usually made from silicon, these make up the familiar solar panels you see on rooftops, which convert sunlight into electricity. Panels of them can be fixed at a south-facing angle, or positioned on a tracking device that follows the sun.
  • Active solar heating: Using a solar collector to heat water or air, which is in turn used to heat the home directly or stored for later use.
Want inspiration? This row of South London homes is a jolly good example of rooftop solar panels. (Steve Cadman/Flickr)
Want inspiration? This row of South London homes is a jolly good example of rooftop solar panels. (Steve Cadman/Flickr)

In all of the above cases, the environmental benefits can kick in quickly. In two to three years, modern solar panels can produce enough energy to recover the amount it took to produce and install the system in the first place, notes Co. “Then it’s just carbon-footprint-free energy to society/planet earth.”

Talking SPFs (Solar Power Figures)

Speaking of free things…getting hooked up with solar power isn’t typically one of them.

Like any new system, up-front costs can get hefty on solar energy upgrades. There are too many variables to provide a complete financial picture here, but the DOE says that the installation cost of solar electric systems is, on average, $8 to $10 per watt. For more info on estimating the cost of implementing solar at home, we recommend checking Energy Sage, a DOE-backed search tool that rounds up quotes on solar installations in your area. To learn about local rebates on installing solar panels, see the DOE’s handy Database of State Incentives for Renewables & Efficiency.

Unlike the short-term environmental rewards, the time it takes to see the financial return on your investment can take a while, and varies widely. Generally speaking, it’ll take less time to make the money back in energy savings if you live in a sunny spot like Arizona; longer if you’re in, say, Vermont. Check out this handy map showing solar energy potential to see the success they could have in different locations.

Still, solar power has proven wildly successful in some pretty diverse locations already. Consider these success stories:

  • Bavaria, Germany: This solar savvy region has three photovoltaic panels per its 12.5 million residents—adding up to more installed solar capacity than in the entire U.S., according to Grist.
  • St. Louis, Missouri: In 2011, the Saint Louis Housing Authority (SLHA) installed solar panels on more than 90 buildings. Energy costs for the common areas are expected to drop by over 75 percent; the agency hopes to see overall costs go down by 15 percent, according to HUD’s Ecowise.
  • Outer space: The space industry has been successfully employing solar power since the ’60s. The oldest manmade satellite still in orbit, the Vanguard 1, has logged more than 6 billion miles—all on solar power, according to the Energy Department website.

So should we all run out and buy some panels already?

Storage Matters

There is solid solar power technology for many homeowners to enjoy right now. For one thing, the PV cells we referred to earlier are exponentially more efficient now than they’ve ever been. Today’s PV cells can achieve 40 percent conversion efficiency, according to the DOE timeline. In other words, of the solar energy the cells are actually exposed to, they convert about 40 percent to electrical energy. Considering that this has increased from only 15 percent in the early 1990’s, that’s incredible progress.

But there’s still a bunch of work to be done in terms of infrastructure to support more widespread use.

One current challenge energy scientists are tackling is the age-old question: What happens at night? Like wind, solar energy is variable—while the demand for power is not. Even at night, Co points out we’re using 60-80 percent of the energy we use at peak hours in the day—so it’s key that we develop good storage, such as better, more efficient batteries, to ensure energy is available as needed.  Many companies and think tanks are working on developing better batteries, including Argonne.

Solar-Fuels-OrgIn addition to batteries, one can also store the sun’s energy in chemical bonds—to create a fuel just like in photosynthesis (a.k.a. “solar fuels” or “artificial photosynthesis”). Scientists around the globe are working on such technologies (generating hydrogen gas from water, recycling CO2 from the air for flue gas to make a combustible fuel, etc.), and it is the Solar Fuels Institute’s goal to connect the labs and bring these technologies to the marketplace.

Another toughie is how to integrate it more into the supply system (as opposed to having every homeowner fend for themselves). “We need to collect and store power when the sun shines for use at night an on overcast days,” says Crabtree. Right now, he explains, solar and wind supply 2.5 percent of U.S. electricity. That number could go up to 20 percent without needing significant storage capability. But for higher levels than that, we’ll need better storage technology and a modernized electrical supply grid that’s more efficient in meeting demand (aka, a smart grid—another VIP topic we’ll have to save for a rainy day).

Still, going solar at home now can be worth the while for many homeowners. Co speculates that the panels themselves won’t significantly improve in terms of more power per square foot any time soon.

So put on your sunscreen, do some homework, and see if solar is a viable option for your home—it may very well be.

EcoMyth Outcome: Myth partially busted

Solar power is indeed a viable option for many homeowners, depending on location and available subsidies. However, to fully maximize the potential for widespread use, more advances in technology and policy are needed.

One Green Thing You Can Do

Take the first step to going solar: Check out the DOE map to learn your area’s potential for solar.

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