Which Direction Should Solar Panels Face?

Which direction should solar panels face?

The sale and installation of solar panels around the world continues to be a booming economy, with an estimated 250 gigawatts of energy now available via solar panels.  Experts expect that figure to approach 4500 gigawatts by 2050. The cost has continued to drop to where solar panel prices are easily in the range of the average homeowner, who may or may not know enough about solar panels to get the best benefit from them.

Which direction should solar panels face?  The direction solar panels should face is either south or west. Traditionally, the best direction has always been south.  But new research favors the west when applying supply-and-demand factors. East is not considered a good choice, and north is totally out of the question.

There are dozens of factors that need to be considered when installing solar panels, not the least of which being the direction they face. Factors like climate, obstructions, trees, and surrounding terrain go into the equation, making some homes and some techniques more suitable for solar panel installation than others. An often overlooked factor is being able to match electrical demand with production.

Follow the Sun

Southern exposure is a valuable commodity in real estate.  The most flattering light for a home or storefront generally comes from the south.  Eastern-facing structures receive full-on sun in the mornings, and western-facing structures have it in the afternoons.  But the southern exposure receives sunlight, albeit at various angles, all day long, from dawn to dusk.  By contrast, a building or home with a northern exposure would always be in the shadows.

Based on that factor, conventional wisdom has said to face solar panels south. And it would not be wrong to do so.  Installations go on every day with the panels facing south.  But is that the absolute best?

Is West Best?

While it’s true that solar panels will receive more light overall when oriented toward the south, it doesn’t necessarily equal more electricity at the crucial time it’s needed.  As solar-equipped homes are normally part of the community energy grid, the important factor is not the raw numbers of potential electrical production, but the reduction in demand across the entire grid.

The solar panels on top of your house may have all this potential energy available at 10:00 a.m., but it isn’t much help to a grid system that is easily keeping up with demand at that time of day.  But in the afternoon, when demand typically peaks, the grid can use all the help it can get from the homes with solar power.

So the theory is, face the solar panels west so that they receive full-on sun at the time when the energy is needed the most.  South-facing panels receive glancing blows of sunlight all day long, but at the critical time of the day, the real solar action is in the west.

The Pecan Street Research Institute Report

The Pecan Street Research Institute blew a hole in a lot of theories regarding solar energy production and the direction solar panels face when it extracted numbers that took supply and demand into account.

What researchers were looking for was the impact that solar energy production had in reducing demand across the power grid.

“The research is the first of its kind to evaluate the energy production of solar panels oriented in different directions.  Pecan Street analyzed 50 homes in the Austin, TX area.  Some had only south-facing panels, others had west-facing panels, and some had both.
 
South-facing panels produced a 54 percent reduction overall, while west-facing solar PV panels produced a 65 percent peak reduction.”

Katherine Tweed, Greentech Media

From the standpoint that solar panels produce energy on demand as it’s being consumed, the Pecan Street project determined that west-facing panels produced 49 percent more energy than south-facing panels.

TOU – Time of Use Pricing

The impact solar energy production has had on traditional energy grids is widespread and is morphing into many components that offer more and more ways for consumers to save money.  Tax incentives in various forms have been in place for some time, rewarding homeowners who install their solar panels with a tax credit or tax deduction.  Some incentives are set to expire soon but may be replaced with new ones.

A growing trend in many places across the country is the adoption of Time-of-Use Pricing (TOU), meaning energy that is used during peak hours is more expensive than at other times of the day.

So for a homeowner with solar panels on his roof, being able to use solar power rather than power from the utility company during peak hours results in significant savings.  For the most part, peak time – as it was in the Austin, Texas research project – is 3:00 to 7:00 p.m.

At that time of day, of course, the sun is in the west, so orienting your solar panels in that direction makes a lot of sense.  The question could be asked about the effectiveness of aiming solar panels to the east.  While the sun would shine directly onto the panels in the morning hours, the demand is less, and therefore, the actual output would be diminished by the relative shortfall in demand.

Roof Pitch Makes a Difference

It’s the age-old paradox of fashion versus function.  American homes, in particular, reflect the housing trends that were in play at the time of construction, ranging from Victorian to ranch, with stops along the way at French provincial and Tudor.

It’s a safe bet that the builder of any home built before the mid-2010s would have given little regard to the pitch of the roof as it relates to the mounting of solar panels.  Even now, any discussion of roof pitch is going to focus more on style or water-shedding than its suitability for as a place upon which to mount solar panels.

Research is lacking, but early indicators support the concept that solar panels installed on flat roofs, or on roofs with a relatively low pitch, produce more energy than those mounted on steeply pitched roofs.

Weather and Solar Panels

If you own solar-powered garden lights or pathway lights, you’ve probably that they don’t last as long after dark following a cloudy day as they do on a sunny day.  If the day was particularly gloomy, they might not light up at all.

The same is true of solar panels, but not on the scale as you might expect.  While the sun is the source of the energy that is transitioned to electricity, the individual solar cells don’t necessarily require direct sunlight.  The sun emits photons into the earth’s atmosphere, and it’s the photons that react with the components of solar cells that create the current.

There’s no question that direct sunlight is best, however.  On cloudy days, solar cells might produce only 25% of their normal capacity.  On stormy, exceptionally gloomy days, the output could be as little as 15% of capacity.

Therefore, locales in Nevada, Utah, Arizona, and parts of California would be more conducive to solar panels, while places with frequent clouds, like Washington, Oregon, and Florida (despite its nickname, The Sunshine State) would be less so.

Before You Buy

  1. Fix the roof.
  2. Look for additional ways to save energy.
  3. Know the two main ways to use solar power.
  4. Confer with local power supplier about being connected to the grid.
  5. Hire an experienced installer who’ll honor the warranty.
  6. Sometimes leasing panels makes better sense.
  7. Get the contract right.

Roof

The first obvious factor is whether your roof is structurally sound enough to support the weight of solar panels and whether it’s in need of reshingling, or will be within a few years.  Solar panels are no replacement for shingles and could make roof leaks worse if the shingles are worn out, so get all structural shortcomings taken care of first.

Your roof should be sunny for as much of the day as possible. If it’s shaded by trees, nearby buildings or surrounding terrain (like a tall hill or mountain due west of your location), then solar panels might not work well enough to justify the expense.

Other Things You Can Do

Make sure your home is already energy-efficient, with proper insulation, weather stripping, and other energy-saving practices before embarking on a solar panel project.

Good overall energy efficiency practices:

  • Attic insulation – 12 to 15 inches of insulation to bring to rating to R-38 or R-49
  • Energy-efficient doors and windows – Fiberglass and vinyl are better insulators than steel or wood.  Gaskets and seals should be in good shape.
  • Close fireplace flues.  Wood-burning fireplaces are infamous wasters of energy.  Ventless gas logs can be set in the fireplace opening and provide more heat than a real fire.
  • Run AC at 74 degrees in the summer, 68 degrees in the winter.

If your home is not energy efficient overall, putting solar panels will not produce the savings they otherwise could.  Home energy checklists are available in numerous locations and online.

Different Types of Solar Power

There are two basic types of solar technologies: photovoltaic and thermal.  Photovoltaic converts light into electricity and thermal uses sunlight to heat water or air for use inside the house.

Most homes would be best served by the photovoltaic process, but homes in extremely cold locales might do better if the solar assist went into heating water or air.

Photovoltaic is the easier of the two to install, and there are more experienced installers for this process.

Connecting to the Grid

The process differs by state, county, and municipality, so be sure to contact the local power supplier and whatever community governing board may be in place to regulate hook-ups.

In some communities, solar owners are reimbursed for energy that’s consumed via their solar panels (and therefore does not come off the community power grid).  Often the rate is the same rate as it would have been if it was the other way around – if the homeowner was drawing power from the grid.  Also, determine the formula that is used for this purpose.  Do you live in a state or city that uses time-of-use billing?  Find out because this can be a huge factor.

Some states are far more generous than others when it comes to incentives and energy reimbursements, and it makes great sense to familiarize yourself with the state or city’s policy before making the investment to purchase and install solar panels.

Find a Reputable Installer

With solar panels, the technology sometimes outpaces the competency, not only of the homeowners but also of would-be installers.  In areas where solar installations are a novelty rather than an established practice, the issue of finding an experienced installer becomes more difficult.

It’s a challenge, but try to find an installer who will be around long enough to honor the warranty.  There’s not a lot to do with the solar panels regarding maintenance, but things sometimes break prematurely, and you want to have someone to call when it does.

Make sure that the supplier of solar panels also services them, rather than contracting the service work out to a third party.  That third party may not even do regular business in your area.

Lease or Buy?

It might never enter the minds of many buyers, but the solar panels may outlive their residency at that particular address.  For this and a few other reasons, leasing the solar panels becomes a viable option.

Lease terms vary, of course, but primarily, the leasing company maintains ownership of the panels, and you pay the company for the electricity used (at a rate less than that charged by the local energy provider, of course).  When the lease is up, or when you move, you walk away, and the leasing company takes back its solar panels and associated hardware.

The benefit of owning your own system is that all the energy savings go to you and no one else, and once the benefits exceed the purchase price, you’ll enjoy an unfettered rate of return.

The panels themselves could last for 30 years or more, but the supporting electronics won’t be able to match that performance.  That all needs to be factored in your decision to lease or buy.

Contract

Your contract should detail the financing terms, warranties, and performance expectations. This may be new territory for you, but it certainly isn’t for the supplier, so don’t be bashful about asking questions.

Solar Technology is Not As Cutting Edge as You Might Think

In 1839, Edmond Becquerel of France, experimenting in his father’s laboratory, created the world’s first photovoltaic cell.  He found that electrodes coated in silver chromide or silver bromide generated pulses of current when exposed to light.

The far-reaching possibilities of the photovoltaic process were not fully realized for many years, but Becquerel busied himself in many other disciplines regarding light and photochemistry.

A century later, scientists made important discoveries in the same realm.  Maria Telkes, a Hungarian who came to the U.S. in 1925, refined methods for generating and storing energy derived from solar sources, and in 1954, three researchers hoping to produce a renewable battery for remote telephone use – chemist Calvin Fuller, physicist Gerald Pearson, and engineer Daryl Chapin built a silicon solar cell.

The first solar-powered phone call was placed Oct. 4, 1955, using a bank of cells on a flat panel pointed at the sun. The device bears a strong resemblance to today’s solar panels.

Composition of Solar Panels

Solar technology is clearly a “green” technology, but even the physical components of the solar panels are earth-friendly.  Solar cells are made out of silicon, the second most abundant element in the earth’s crust. (Oxygen being number one.)

Silicon doesn’t have to be mined. It can be produced.  It’s “grown” in a tube as a crystal, rolled out like salami, and cut by lasers into extremely thin wafers that become the prominent element of a solar cell.

Solar cells have efficiency ratings based on the amount of electricity converted per square inch of exposed space.

“Let’s say you have 100 square feet available on your roof. In this limited space, if panels are 10 percent efficient, its less than 20 percent. Efficiency means how many electrons they can produce per square inch of silicon wafers. The more efficient they are, the more economics they can deliver.”

Robert Margolis, a senior energy analyst at the National Renewable Energy Laboratory

A Recent Discovery of Interest

While silicon has proven to be a reliable root element in the manufacturing of solar cells, scientists continue to investigate new methods and new materials that might be better than what is currently in place.  For example, silicon has an upper limit of 29 percent efficiency in converting light to energy.

A mineral known as perovskite has been shown to achieve efficiency ratings of up to 20 percent, which is less than that of silicon, but it is much easier to artificially produce, and its light-to-energy process is much simpler. But the findings occurred in a sterile lab environment.  Real-world capabilities are still under scrutiny.


Title image by Walt Stoneburner

spgenie

Hi I'm Harris the spgenie! As an engineer, I found myself doing tons of research about solar power, the types of panels, how to store the energy and the best way to finance the project. I thought I'd start this blog to share my findings. I hope you find this useful.

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