How Do Solar Panels Work?

Like most great ideas, solar panels are a simple concept. However, understanding how they work, let alone making them work, is complicated. Once the sun's UV rays reach a home's solar modules, the process of converting this energy into usable power has only just begun. However, understanding how solar arrays work can give homeowners confidence in how advanced this form of renewable energy has become, making them feel more comfortable purchasing their own solar panels.

How Do Solar Panels Work? Residential Solar Power for Beginners

Just like other industries, solar experts have solar-related jargon that few outside the industry understand. Solar terms, like inverter, kilowatt, kilowatt hours, power grid, and monocrystalline, aren’t typically used outside of electricity-related industries.

As a newbie to solar, it's helpful to know the basics. Understanding the basic idea behind how solar works helps customers feel comfortable considering solar for their homes and comparing solar companies.

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The Epicenter of Solar Power – the Sun

Like many forms of matter in our galaxy, solar panels work and exist because of the sun. This gigantic mass of energy fuses hydrogen into helium, which facilitates its heating process and sends light as both particles and a series of wavelengths toward earth.

Of these wavelengths, 99 percent use visible light, which contain ultraviolet rays and infrared rays. UV rays have shorter wavelengths and, therefore, are more energetic than the sun's other rays.

How Solar Panels Generate Electricity

Each residential solar panel has roughly 60 cells. When the photons in UV rays reach the modules, each cell has electrons that create an interplay of electrical motility, which produces a electric current.

While these basics generate electricity, remember, a solar panel's ability to produce energy for homes has many determinants, including, but not limited to, roof space. Solar panel function isn't the only aspect of solar worth assessing when considering rooftop solar. Installers and homeowners must also considering the kind of solar installation they want, their system offset, and the composition of the panels they'd like to power their homes.

Types of Solar Panels

While the composition of a solar panel matters, its features and benefits are not as easily understood as other commodities, like cars. While a solar panel's features rarely mean anything to homeowners considering rooftop solar, its composition and inner workings play a huge role in the potential ROI homeowners can generate with solar. Determining the efficiency rating of solar panel types comes mostly from the electrons’ ability to potentiate energy within the solar cells of each individual module.

Monocrystalline Solar Panels

If we hyphenate the word monocrystalline, the meaning of this term becomes clearer: Mono-crystalline means one crystal.

The solid crystals used in monocrystalline solar panels give the electrons added movement within the solar panel, making them more efficient in converting the sun's rays into usable energy. Most monocrystalline solar panels use silicon in their crystals.

These cells are manufactured by melting silicon and dipping crystals of silicon into liquid, forming an ingot. The ingots are sliced into silicon wafers, which form the square-like shapes in the solar panel, making these cells visible.

Polycrystalline Solar Panels (Also Referred to as Multicrystalline Solar Panels)

As the name suggests, polycrystalline solar panels use a manufacturing process that involves many fragments of silicon. Both polycrystalline and monocrystalline solar panels rely on melted silica. However, in the polycrystalline manufacturing process, the silicon cools and melts together. These solar panels come in at a cheaper price point, making them a popular alternative to monocrystalline. However, melting fragments of silica together restricts electron movement in the cell of the solar panel, creating a less efficient form of solar energy production for homeowners than monocrystalline moduels could provide, even in sunnier cities, like Reno, Nevada or San Antonio, Texas.

Amorphous Thin-film Solar Panels

Thin-film panel creation involves putting a semiconductor, such as silicon, onto glass or another similar material known as substrate. These solar panels have the lowest efficiency.

If a homeowner has a lot of space, these might work. However, typically thin-film solar panels don't provide an ideal solution for home solar installations.

Residential Solar Installation can take longer with thin-film solar panels. Using these kinds of solar panels can increase the cost of installation. Most solar installers only handle relevant and modern solar products, which brings us to our next point regarding innovation and thin-film solar panels. Amorphous Panels are Past Their Prime and Have Already Been "Abandoned" by Innovators in the solar energy field. Thin-film solar panels first received recognition and application to solar projects in the 1990s. However, as solar technology has continued to advance, this solar panel type has fallen behind the competition. While thin-film solar technology still has its place in smaller technologies like calculators and wearables, they are not ideal for the high electricity needs of the 21st-century residential solar energy landscape.

How Solar Panels Convert Solar Energy into Electrical Energy: The PV/Solar Inverter

Without the inverter, solar panels become useless. The inverter turns direct current (DC) from the solar panels into alternating current (AC), so homes can use it. It connects the solar panels to the home, and battery backup where applicable, and, ultimately, the power grid.

On a more technical level, solar panels sometimes have electronics inserted into their photovoltaic (PV) structure to facilitate a maximum power point tracking (MPPT) mechanism. This mechanism ensures electrical output every five to ten minutes, guiding solar panel production.

While important, solar panels only make up a portion of a complex process. The various types of inverters play nuanced and distinct roles in turning direct current absorbed by solar panels into alternating current.

String Inverters

A string inverter takes the DC from an array of solar panels and transforms it into AC. The drawback of a string inverter comes from the impact of shade on production.

The Best Conditions for String Inverters

Homes that have full sun exposure make the best fit for string inverters. Cutting down or trimming trees around the home may provide enough light for a solar service team to justify installing a string inverter.

String inverters work well with solar panels installed in blocks, such as four rows with four solar panels per row, in one location on the roof. It's best if the roof is not obstructed.

To learn more about monitoring an existing SMA string inverter, see this video with one of our solar technicians explaining the SMA set up.

Central Inverter

Central PV inverters are a larger version of a string inverter. Their design allows them to support more strings of solar panels.

Uses for Central Inverters

These inverters work best for commercial-grade solar installs. They require less wiring and conduit connectivity. However, they also need a combiner box.

Micro-Inverters

Microinverters consist of mini inverters installed on the back of each solar panel. These inverters convert the DC from the solar panel to AC at the solar panel instead of further along.

How Microinverters Handle Shade

Microinverters manage each solar panel individually, which decreases the impact that shade has on production. It also makes adding solar panels later easier.

Microinverter Monitoring

Microinverters, monitor each solar panel. Allowing solar installation technicians to monitor the system’s production remotely and resolve any inverter issues that arise.

Power Optimizers and String Inverters: A Newfound Trend

Some string inverters have DC power optimizers. While a typical string inverter, like an SMA Sunny Boy, will have efficiency at the peak sunlight hours of any given day. But an optimized string inverter, like the SolarEdge, will provide solar homeowners consistent power throughout the day.

Optimized string inverters have a power optimizer under each solar module. These devices increase the DC before sending it to the inverter, which improves the power efficiency of the residential solar array.

Optimized String Inverters and Shade

The SolarEdge inverter, which Go Solar Group uses, is an Israeli-engineered string inverter with optimizers. The biggest pro of using the SolarEdge inverter comes from the decreased impact shade has on the efficiency of the array than a solar panel connected to a typical string inverter.

Using Optimized String Inverters on Homes with Limited Space

Because optimized string inverters can use shorter strings, this option works well for rooftops with limited space. Short panel strings allow the installer to take advantage of multiple smaller areas.

Maintenance of Optimized String Inverters

Optimized string inverters have an inverter installed at the ground level, which means most inverter problems don't require installers to go on the roof. Power optimizers on the back of the solar panels also allow solar installers to monitor each solar panel, so they can determine the cause of an issue without having to test every solar panel.

Battery Backup: How to Get the Most out of Declining Net Metering Returns

Most solar homeowners don't purchase battery backup because they have net metering rates that cover the cost of the power pulled from the grid when the sun isn't out. However, those who want power during an outage or don't have a great net metering rate should consider battery backup. Battery backup consists of a battery that can charge with the excess energy that a solar array produces. Having enough battery backup to meet all of a homeowner's energy needs is ideal, but unfortunately, this isn't an option for everyone. To meet this range of needs several battery backup options have come on the market. They range from portable batteries to home batteries. Which one to get depends on the customer's needs and priorities.

Off-grid Solar and Home Batteries

Home batteries provide the best backup option for people who need an off-grid system. It's close to the same price or slightly cheaper than having power lines brought to a remote location, and it provides people with the tools to become self-reliant.

Unfortunately, off-grid solar isn't an affordable option for the average solar customer. Battery backup technology has progressed, and more options at competitive prices continue to become available. However, nothing has come close to dethroning the Tesla Powerwall as the market's premier form of whole house battery backup.

Battery Backup and Solar Array Compatibility

Until home batteries can catch up to consumer needs and price range, there is another option to help solar homeowners when the power goes out. Emergency battery backup allows individuals to power essential items when the grid goes down. Go Solar Group offers a home battery and several emergency battery backup options.

Battery Backup provides security in an emergency. Regardless of whether the solar customer has decided to purchase battery backup, it's good to make sure the system can interoperate with the market's leading battery options.

Not all photovoltaic systems work with battery backup. When battery backup prices go down, and they will go down, customers who have checked for compatibility can easily take advantage of the opportunity.

Installing a Net Meter

A net meter measures the electricity put on and taken off of the power grid. The power company installs the net meter after the homeowner signs their net metering agreement and installs their solar array. Because home battery technology hasn't evolved into a more affordable option, most people sign up for a net metering agreement.

This agreement allows the utility's customers to use their excess solar power to offset the electricity pulled from the grid at night. The power company decides the worth of the solar-generated electricity put onto the power grid by the customer. These rates often determine how big of a system homeowners install and what forms of energy storage they choose.

The Power Grid

A typical home connects to the grid, but in a very different and less efficient way than homes powered by solar. The power grid creates an electrical highway composed of power lines and collection towers that connect our homes to large power plants. Most of these power plants use coal, though some rely on other fuel sources such as natural gas.

Solar and Battery Backup's Relationship with the Grid

Those who don't have battery backup stay connected because they don't have another power source at night or during inclement weather. Those with home batteries that could provide enough power to keep a home running often stay connected because it adds another layer of security.

How Do Solar Panels Work within the Broader Residential Solar Process?

While converting solar energy into solar power has a complicated process, those looking into solar, don't need to know all the gritty details of how a solar array works. They do, however, need to understand the basics of residential solar, so they know what to look for in a solar array.

Those looking at residential solar have a couple of things they need to keep in mind. First, they need to make sure that the solar array will meet their energy needs. Secondly, they need to have a backup-power option picked.

Sizing Solar Correctly for a Home

Each home has different energy needs. One family may have large energy consumption items, such as a hot tub or an aquarium, while another family in the same size home hardly turns on the lights.

Because of energy consumption differences, solar estimates use the home's energy use, also known as usage, to determine the size of solar array a home needs. A correctly sized system prevents homeowners from being charged for energy that the solar array could have produced or from overproducing.

The Reason Solar Arrays Need Battery Backup

After DC from the solar panels converts into AC, it can power a home. However, most use more electricity at night. Without the sun, solar panels don't have any UV radiation to absorb, which means it doesn't have anything to convert into electricity. Thankfully battery backup can help solve this problem.

Designing a Solar Panel System: Space, Production, and Projections

While determining the usage of the home constitutes the first step for solar design, it isn't the only step. A properly sized system has a couple of factors that goes into it.

Some of these elements include determining the available space, possible shading issues, power needs of the home, calculating solar production, system type, and projected factors. Below we have gone through the basics of what goes into configuring a system.

Available Space for Residential Solar

Determining the amount of space a home has influences the size and type of solar array the homeowner can install. Homes that don't have adequate unshaded space can't install solar. If the roof doesn't have enough space, consider a ground mount.

The Amount of Space Needed

On average residential solar panels take up 5.4 feet by 3.3 feet, which means each solar panel needs about 18 square feet of unshaded space. The number of solar panels a home needs depends on the wattage of the modules, home usage, and the production offset of the system.

The Impact of Shade on Solar Panel Placement

One of the determining factors of solar panel placement includes shade. Shaded solar panels don't work as well. Homeowners with large trees that shade the roof may want to consider trimming them to optimize their roof for solar.

Current Power Use and Estimated Solar Production

To properly size a solar array, the home's typical energy use needs determining. That energy usage then needs to match solar production.

Home Usage

Energy usage includes the amount of electricity that a home uses. Utility bills often label it as energy usage and measured it in watts or kilowatt-hours (kWh).

Production Metrics and Important Units of Measurement for Solar Panels

After determining a home's annual energy, PV designers match it with solar production. To match the production to the consumption, they use a slew of terms and math. Common solar terms include kWh, voltage, amperage, wattage, net metering, and peak solar production hours.

Kilowatt Hours

(kilowatts) (number of hours running) = Kilowatt Hours

Commonly expressed as KWH or kWh, kilowatt-hours measure electricity and solar production. Although the term seems confusing, it's only a verbal expression of a simple multiplication problem.

An example of this type of equation in action includes finding the kilowatt-hours for a 7,000-watt (7 kW) rooftop solar array producing solar energy for 8 hours on one particular day. After doing the multiplication problem above, we find that the total number of kilowatt-hours (kWh) equals 56.

Voltage

Energy/ Charge = Voltage

Voltage equals the pressure of an electrical current. Energy provides voltage, which becomes necessary for the flow of an electrical current. Symbols often used for voltage include V and U.

Amperage

Wattage/ Voltage = Amperage

Amperage equals the strength of an electrical current measured in amperes. Essentially, it's the amount of electrical current flowing through a conduit or system. The product of voltage and amperage equals the amount of wattage. It only takes .75 amps to stop someone’s heart.

Wattage

(voltage)(amperage) = wattage

For solar installation technicians to do their jobs correctly, they must configure the system to maximize wattage, which equals the total amount of electricity conducted. Each solar panel on a solar-powered home typically has 250 to 310 watts.

Peak Solar Production Hours

Unfortunately, not every hour of the day throughout the year provides that same amount of ultraviolet radiation. The United States ranges from three to five peak hours per day.

The peak production hours for a geographic location depends on the intensity of light produced during the day. These hours occur when the sun hits the highest spot in the sky. To find the peak hours for a specific area, use an isolation map.

Electronics perform best when allowed to cool. When allowed to cool on a clear-cool day, solar panels become more efficient than on a cloudless hot one. However, because the length of the day increases, it's typical to have more production hours during the summer, and in areas closer to the equator.

Projected Solar Elements that Determine System Design

Other considerations that go into solar array design include the projected weather conditions and the longevity of the array.

Weather Conditions

matching the necessary size of a solar array with the usage of the home comes from historical weather patterns and the projected amount of sunlight the solar panels can absorb in an average year.

Will my solar panels work in the wintertime or with snow?

In the winter, snow concerns many. When snow covers solar panels, they won’t produce as much electricity. However, they often produce enough to melt the snow.

If there isn't a large build-up of snow, the solar panels heat up and melt the snow as they absorb sunlight throughout the day. However, when thick, the snow won't melt in a day, making it hard for any UV light to get through the snow and to the solar panels.

If the build-up of snow gets too thick, it's time to invest in a roof rake. These devices allow homeowners to pull the snow off without needing to get on the roof. It's important to make sure the roof rake has rollers to protect the roof and solar panels from possible damage.

The longevity of the Array

A solar array is a 25-year investment because solar panel warranties typically cover this time frame. While solar panels have and do last longer, all electrical equipment becomes less efficient as it gets older.

Environmental Considerations

While solar panels generate green energy, many have concerns about the environmental impact of solar panel manufacturing processes. Some things to consider when trying to find an environmentally conscious solar panel provider include manufacturing processes and recycling.

Which Solar Panel Manufacturers Can I trust to Keep Solar Energy Green?

Tons of solar panel manufacturers have popped up across the globe. Competitive pricing has become one of the main drivers for solar panel installation.

However, super cheap solar panels often come at a high environmental cost. Solar power plants that take short cuts often have low land and air quality as a result.

Using solar panels helps our air stay clear, but short cuts taken during production can decrease these benefits. For those who want solar because they care about the environment, we highly recommend looking at the solar panel manufacturer.

Silicon Valley Toxics Coalition's scorecard provides one way to check for social responsibility in manufacturing. These scorecards help people better determine the environmental friendliness of different solar panel manufacturers.

Is There Waste from Solar Panel Production?

Although cleaner than coal and natural gas, solar panel production isn't clean. Chemicals such as cadmium telluride, copper indium selenide, cadmium gallium( ii) selenide, copper indium gallium (di) selenide, hexafluoroethane lead, polyvinyl fluoride, crystalline silicon and silicon tetrachloride all take part at some point in the process.

A byproduct of toxic sludge forms after removing these metals and toxins from the water used to manufacture solar panels. If the manufacturer doesn’t have waste treatment equipment, this waste transports to an approved dump.

For some time light has shined on this topic and as a result, companies have given more consideration to waste management. Manufacturers with a high solar scorecard, means they responsibly handle the waste produced and trying to produce as little waste as possible.

A study done by FLASH and funded by Technology Foundation STW found that in order to avoid an energy sink we need to make sure that we can recoup energy waste faster than we create it. In their results they made this statement:

“Energy pay-back times drop from around 5 years in 1992 to around just under 1 year for poly-Si and just over 1 year for mono-Si PV systems currently.”

This means the process of creating solar panels has and continues to improve. We have to take into account that solar started in the 70s, making the technology relatively young. Recouping waste output within a year of solar array use is impressive.

Recycling Solar Panels

Because solar panels last at least 25 years most solar panels don't need recycling, but they will. As a result, efforts to recycle these properly have transpired.

If we don’t do our part to make sure our panels get disposed of properly, toxic substances from these panels could prove a huge hindrance to renewable energy’s mission. Right now Europe has taken the lead but, as time goes on recycling solar will become mainstream.

As of right now, technologies and recycling processes can recycle 96 percent of PV waste. As the need arises, these facilities will become more popular.

Solar Energy Facts, FAQs & Information

What Do Solar Power Plants Do?

When it comes to powering a city, there’s more to generating solar electricity than at-home solar systems entail, and that’s where solar power plants come in. Although Go Solar Group does not specialize in any services or products tailored to solar power plants, we know a lot about them and where they fit in the solar energy landscape. Solar power plants can generally divide into two distinct categories: photovoltaic plants and solar thermal power plants.

The latter of these two generates electricity by concentrating the photoelectric energy of the sun. The prior of these two kinds of power plants use photovoltaics, the kind homeowners put on their rooftops every day, and in increasingly large numbers – residential solar.

This means that every residence with rooftop solar can technically call itself a power plant, which is a pretty cool concept to think about!

How Does Solar Power Work at Night?

Solar panels use the light waves from ultraviolet rays that the sun produces to excite the electrons in the cells of a solar panel and create a current. At night, however, these specific light wavelengths aren’t there to get the electrons moving and create a charge.

Moon Power and Lunar Panels: Fact or Fiction?

The moon reflects the light that comes from the sun to the earth. These wavelengths are longer than the ultraviolet rays used by the sun’s direct light. Longer wavelengths do not provide enough electron movement for the panels to power anything.

Unfortunately, panels have not, as of yet, effectively used light reflected from the moon or produced by the stars lightyears away. For now, moon/lunar powered panels are still science fiction.

Salt of The Earth: Is this the key to Unlock Solar Nightlife?

In 2009, articles started to come out with a new plausible solution to using solar power at night. Scientists found that because salt has a high melting temperature, it's perfect for storing heat.

The Crescent Dunes Solar Energy Project in Nevada uses molten salt heated by the sun during the day. This superheated salt then powers a turbine at night or when the weather is not conducive to solar power.

This idea has proven a much cheaper option than lithium-ion batteries for storing solar power. This process, however, requires a lot of space, and the technology hasn’t converted to a usable format for homeowners. Only time will tell where this technology will go.

Financial Considerations: How the Way Your Solar Panels Work Impacts the Rate of Return

When it comes to making large additions to your home all financial aspects need consideration. Replacing your current power provider for the next 25 plus years is a large addition.

People need to know what to expect so that they can recognize when they have a good deal. Using a solar savings calculator will help you get started. Here are a couple of other things to keep in mind while considering finances.

Know that the Biggest Solar Installers Usually Aren’t the Best Options

The National Renewable Energy Laboratory did a study on the relationship between installer pricing and firm size in April of 2017. They found that large firms often aline prices with their brand’s reputation. A smaller firm, on the other hand, will likely cite fair prices for the customer.

Large installers typically charge about $2,000 to $5,000 more than a smaller one. This doesn’t mean you should completely write them off as an option. Just make sure you look at all the aspects of the product before deciding to go with a big name brand solar installer.

Solar Production and Service Warranties: An Important Consideration for Homeowners

Warranties vary depending on the manufacture of the product. A couple of different types of warranties typically come with a solar installation.

A solar installation normally has a 10-year materials warranty. This warranty covers certain materials damaged within the first 10 years of use.

Production warranties typically last for about 25 years. These warranties guarantee a certain percentage of product production. Most guarantee solar panels will still produce between 80% to 90% of their original capacity in the first 25 years of use.

Making sure that the manufacturer has good warranties will ensure the investment will last in the long run. Go Solar Group uses Axitec panels these panels have a 15-year product warranty and a 25-year production warranty of 85 percent.

Advantages and Disadvantages of Solar Power for Homeowners

No matter what there some pros and cons will exist. For all of the major decisions Benjamin Franklin had to make, he would put together a pros and cons list. His list helped him to properly weigh the best decision. We have put together some of the pros and cons we have seen in solar power for you to analyze for yourself.

Advantages of Solar Power for Homeowners

Freedom from reliance on coal power.
25+ years of no or minimal electric bills
Emergency preparedness
Several Emergency battery back-up options( with Go Solar Group)
Providing micro-loans to motivated Africans ( with Go Solar Group)
Federal and state incentive programs designed to make solar affordable.
Increases financial security
Increases the value of your home.
Technological advancement is continuing to make manufacturing a cleaner process.
Process in place to make panel recycling part of the future.
Power backup options are available and continuing to advance.
If you get a loan for solar there is no down payment.
If you pay cash for solar you will most likely get a discount on the whole system.
Referring friends who want solar can decrease how much you end up paying for your system.
Your solar array will decrease your carbon footprint while in use.

Disadvantages of Solar Power for Homeowners

Currently, the recycling of old photovoltaic systems is not very high.
Not all of the panel manufacturers report their energy efficiency.
Not all Solar panel companies install their systems. (Go Solar Group does)
Getting solar will most likely require a loan of some sort.
Solar arrays do not produce energy at night.
If you live in an area that doesn’t have a net metering program of some sort you may find it more difficult to get solar.
Buying battery backup for your home is expensive right now.
Not all solar arrays come equipped to have battery backup added to them. (All of Go Solar’s are)
Solar industry growth could cause an energy sink if unchecked.
Having to clear heavy snow off of your panels. (if you live in a colder climate)

We strongly encourage people interested in solar to consider all the pros and cons of solar as an industry and individual solar companies. Getting all the facts and comparing them will help you to make the best decision possible.