With so many different gadgets and technologies that could leverage solar power in the modern era, many are wondering “how is solar energy used?” Whether it’s powering renewable transportation or charging a wireless speaker, the list of examples of solar energy is endless, leaving many homeowners wondering how far they can really go when they decide to “go solar.”
What is solar energy used for?
Solar energy uses captured sunlight to create photovoltaic power (PV) or concentrated solar power (CSP) for solar heating. This energy conversion allows solar to be used to power auto motives, lights, pools, heaters and gadgets.
There’s no doubt that the solar-powered products available on the market are increasingly complex. Here’s EnergySage’s top five list for examples of solar energy: solar transportation, solar tech, solar lighting, solar heating and our favorite – rooftop solar.
With community solar, anyone can switch to solar technology. Learn more
Solar Powered Transportation: A New Use of Photovoltaic Energy
An innovative practice to effectively make use of the sunshine is with transportation powered by photovoltaic (PV) energy. Railroads, subways, buses, planes, cars and even roads can all be powered by solar, and solar transit is becoming a popular offering in the renewable energy sector. Recently, the solar powered-aircraft Solar Impulse 2 made its way around the world, soaring across the Pacific and making big splashes in iconic photographs. Meanwhile, solar buses are helping China reduce its carbon footprint while simultaneously maintaining efficient mass transit in densely populated cities like Beijing. Finally, solar cars are starting to play a role in racing competitions around the world, especially in Australia where the SolarSpirit model has gained major recognition. With these advances and more, there’s no question that solar power is the transforming transportation sector around the world.
Wearable Solar Tech: A Personal Way to Use Solar Power
Powering consumer electronics has become a common solar power use in today’s world – solar-powered chargers like Anker’s Powerport can charge anything from a cell phone to a tablet or e-reader. There are even solar-powered flashlights that can be charged by being exposed to sunlight. For those curious about the top products in solar tech, check out this top 10 list of uses for solar devices:
- Cell phones
- Wearables
- Music speakers
- Solar air conditioning
- Tablets
- Thermostats
- Solar dryers
- Solar visor radios
- Freezers/mini-fridges
- Rechargeable flashlights
As the world moves away from fossil fuels and seeks renewable sources for everyday electronics, there’s no doubt that solar will continue to be adopted by the masses for any product that can be exposed to sunlight. The ultimate goal: use solar products to reinvent the way we think about power usage, and reverse the expectation for how devices should be charged. And as the conversion efficiency of solar continues to improve, this trend will expand into new markets and new products.
For example, wearable solar could soon make Apple Watches and Fitbits much more appealing to consumers – unlike their standard counterparts, solar powered smart watches don’t need to be plugged in to recharge every night. The real question is, will these large technology companies be able to integrate wearable solar technology into their products before an emerging brand beats them to it?
Solar Lighting: A Popular Example of Solar Energy
One of the easiest ways to improve home efficiency is to add outdoor solar lighting to your property. Unlike traditional exterior lights, solar lighting requires no complicated setup as the lights are wireless and harness sunlight during the day to circumvent the need for grid-supplied electricity at night. Though solar lights are not yet as common as solar panels, they are quickly joining the likes of LED lightbulbsand smart home thermostats as a cheap product that can reduce electric bills and improve the efficiency of your home.
Additionally, the aesthetic of modern solar lighting can significantly improve the outdoor decor of a property. Elaborate lighting arrays can improve the exterior design of a property, are often as cheap as $20 per light, and are available at major home retailers such as Home Depot. The availability and low cost of these lighting products are one reason why it’s so common to see solar powered street lights – keep your eye out for those like the one pictured above.
Solar Heating: Using PV for Thermal Energy
Many homeowners are unaware that solar water heaters and solar space heaters are an effective way to heat one’s home without making the larger investment of installing solar panels. Solar space heaters harness sunlight and convert it into thermal energy with the use of liquid or air as a medium, while solar water heaters use water as a method for thermal transfer. These solar heating systems can either be passive or active – while passive systems utilize natural circulation, active systems use pumps to circulate water and generate heat. Homeowners who install a thermal solar array on their roof can expect 5 to 10 percent returns with a system that costs a fraction of a full solar panel installation.
A major benefit of solar thermal technology is the ability to heat your pool at a more cost-effective rate than conventional alternatives such as oil and gas pumps. According to the U.S. Department of Energy, “solar pool heating is the most cost-effective use of solar energy in many climates.” Wondering how solar heated pools work? At its simplest, the technology uses a solar collector that harnesses sunlight and converts it into heat. Water is then drawn through the collector as a means of heating the pool. This technology can also be used to cool the water at night (typically necessary only in hotter climates). Solar heating systems range between $3,000 and $4,000 and can provide a payback period as short as one and a half years.
The cost of solar is dropping across the nation. See prices in your area and get free solar quotes on the EnergySage Marketplace.
Rooftop Solar: A Homeowner’s Best Friend
With so many amazing gadgets and devices available under the sun in 2018, it’s easy to overlook the most important use of solar energy: rooftop solar. While solar energy can be used to fly an aircraft and charge a battery, it can also be used to save homeowners thousands of dollars every year by cutting their energy use, carbon footprint and utility bills.
As you consider the various ways to go solar, make sure to first estimate your potential solar savings and see what a solar investment could do for your household finances. Utilizing smaller products and home improvements to improve the efficiency of one’s home is a great practice, but at the end of the day, the ultimate opportunity to improve one’s carbon footprint and electric bill is with a home solar panel installation. If you’re starting to think about going solar, join the EnergySage Solar Marketplace for free in order to start comparing multiple installation offers from the top pre-screened solar companies in your area.
How do solar systems produce energy?
Solar power is arguably the cleanest, most reliable form of renewable energy available, and it can be used in several forms to help power your home or business. Solar-poweredphotovoltaic (PV) panels convert the sun's rays into electricity by exciting electrons in silicon cells using the photons of light from the sun. This electricity can then be used to supply renewable energy to your home or business.
To understand this process further, let’s look at the solar energy components that make up a complete solar power system.
The roof system
In most solar systems, solar panels are placed on the roof. An ideal site will have no shade on the panels, especially during the prime sunlight hours of 9 a.m. to 3 p.m.; a south-facing installation will usually provide the optimum potential for your system, but other orientations may provide sufficient production. Trees or other factors that cause shading during the day will cause significant decreases to power production. The importance of shading and efficiency cannot be overstated. In a solar panel, if even just one of its 36 cells is shaded, power production will be reduced by more than half. Experienced installation contractors such as NW Wind & Solar use a device called a Solar Pathfinder to carefully identify potential areas of shading prior to installation.
Not every roof has the correct orientation or angle of inclination to take advantage of the sun's energy. Some systems are designed with pivoting panels that track the sun in its journey across the sky. Non-tracking PV systems should be inclined at an angle equal to the site’s latitude to absorb the maximum amount of energy year-round. Alternate orientations and/or inclinations may be used to optimize energy production for particular times of day or for specific seasons of the year.
Solar panels
Solar panels, also known as modules, contain photovoltaic cells made from silicon that transform incoming sunlight into electricity rather than heat. (”Photovoltaic” means electricity from light — photo = light, voltaic = electricity.)
Solar photovoltaic cells consist of a positive and a negative film of silicon placed under a thin slice of glass. As the photons of the sunlight beat down upon these cells, they knock the electrons off the silicon. The negatively-charged free electrons are preferentially attracted to one side of the silicon cell, which creates an electric voltage that can be collected and channeled. This current is gathered by wiring the individual solar panels together in series to form a solar photovoltaic array. Depending on the size of the installation, multiple strings of solar photovoltaic array cables terminate in one electrical box, called a fused array combiner. Contained within the combiner box are fuses designed to protect the individual module cables, as well as the connections that deliver power to the inverter. The electricity produced at this stage is DC (direct current) and must be converted to AC (alternating current) suitable for use in your home or business.
Inverter
The inverter is typically located in an accessible location, as close as practical to the modules. In a residential application, the inverter is often mounted to the exterior sidewall of the home near the electrical main or sub panels. Since inverters make a slight noise, this should be taken into consideration when selecting the location.
The inverter turns the DC electricity generated by the solar panels into 120-volt AC that can be put to immediate use by connecting the inverter directly to a dedicated circuit breaker in the electrical panel.
The inverter, electricity production meter, and electricity net meter are connected so that power produced by your solar electric system will first be consumed by the electrical loads currently in operation. The balance of power produced by your solar electric system passes through your electrical panel and out onto the electric grid. Whenever you are producing more electricity from your solar electric system than you are immediately consuming, your electric utility meter will turn backwards!
Net meter
In a solar electric system that is also tied to the utility grid, the DC power from the solar array is converted into 120/240 volt AC power and fed directly into the utility power distribution system of the building. The power is “net metered,” which means it reduces demand for power from the utility when the solar array is generating electricity – thus lowering the utility bill. These grid-tied systems automatically shut off if utility power goes offline, protecting workers from power being back fed into the grid during an outage. These types of solar-powered electric systems are known as “on grid” or “battery-less” and make up approximately 98% of the solar power systems being installed today.
Other benefits of solar
By lowering a building’s utility bills, these systems not only pay for themselves over time, they help reduce air pollution caused by utility companies. For example, solar power systems help increase something called “peak load generating capacity,” thereby saving the utility from turning on expensive and polluting supplemental systems during periods of peak demand. The more local-generating solar electric power systems that are installed in a given utility's service area, the less capacity the utility needs to build, thus saving everyone from funding costly additional power generating sources. Contributing clean, green power from your own solar electric system helps create jobs and is a great way to mitigate the pollution and other problems produced by electricity derived from fossil fuel. Solar-powered electrical generating systems help you reduce your impact on the environment and save money at the same time!
How do solar panels produce electricity?
The process of generating solar energy can be a slightly mysterious topic to some. Have no worries, we are here to make it easy for you to learn how solar panels produce electricity.
The basic solar components
The first step in knowing how solar panels work is to understand how they’re made. Many of them use silicon as a go-to material, one of the most common elements found on our planet. Since creating silicon crystals of suitable quality is a difficult and expensive process, home-solar electric systems are usually built from similar, but less expensive materials1. Like copper, indium, gallium, and selenide (CIGS); which aren’t as efficient as high-quality silicon, yet still, provide adequate amounts of power –– at a reasonable cost –– for most residential needs. It’s a value win!
During manufacturing, small amounts of other elements are introduced to alter the electrical charges of the silicon atoms. This results in strips of negative (n-type) silicon, which has an extra electron; and positive (p-type) silicon, which is missing one electron. Don’t feel bad for this last guy, though. When sandwiched together, these two types of silicon form a photovoltaic cell –– and when multiple photovoltaic cells are placed under glass simultaneously, they give us the cool solar panels we see atop buildings today. That’s what we call good teamwork.
Inside each solar panel, there’s a conductive metal plate connected to wires that lead to a fused array combiner. A device is used to collect energy through an inverter, where the energy’s natural-direct electrical current is changed to the alternating electrical current required to power human-made structures. Yup, just like your lovely home.
Transforming solar power into electricity
Sunlight is a form of energy consisting of invisible particles called photons, that have energy, but zero rest mass. Maybe laying off the coffee for a few days would help. When photons come in contact with other particles, energy expands in several ways depending on the kind of atoms they touch. Most times, heat is generated when this happens. Like Paris would say, “That’s hot!”
On the other hand, electricity is produced when electrons circle atoms2, the reasoning behind why photovoltaic cells contain materials with different electrical charges. See, when the Sun hits a silicon crystal, the electrons inside of it begin to jump up and down. And eventually, some of them become so charged up, they break free and move more freely. The n-type silicon electrons seek out the ones in p-type silicon to replace the missing electrons within their atoms — producing an electrical current from the motion of these electrons.
The amazing semiconductor qualities of silicon (and comparable materials) make it possible to sustain constant electron imbalances. Meaning, a steady supply of solar electricity is going to be at hand every time the photons hit the solar panels — a current collected by wires and carried throughout the system. That wasn’t too complicated, right?
4 factors that mess with solar electricity production
You’ve solved the solar-energy-production puzzle. Yay! Now, it’s important to be aware of the factors that must be carefully considered before, during and after the design and installation of any solar system. Here are the infamous four:
1. Shade: You may already know this, but shaded solar panels3 won’t produce the same amount of energy as those in direct sunlight. So, if your roof is sun-deprived by un-trimmable trees or non-removable elements; solar may not be the best solution for you. At Sunrun, we offer effective solutions to help prevent excessive performance loss. We can leave the shady characters for a new Netflix series. Don’t you agree?
2. Seasonality: Like the weather, solar energy production varies day-by-day and month-to-month. A cloudy, winter day4 won’t be as productive as a sunny, summer one; the important thing here is to focus on the year-round sunny picture. For example, snow can sometimes reflect light and improve PV performance. So in reality, a cold month will only become a solar antagonist if the panels are covered with slush. If Frosty the Snowman comes, he will be asked to leave. Sorry, not sorry.
3. Tilt: Unlike a pinball machine, solar panels can benefit from a good tilting. The location, the direction your home is facing5, and even your roof’s pitch, have a deep effect on how a system works. Ideally, solar panels should be at the same angle as the latitude where they’re mounted — and pitches between 30-45 degrees usually work well in most scenarios. Happiness is a matter of perspective, indeed.
4. Azimuth: The azimuth angle6 is the compass direction from where the sunlight is coming. At solar noon, the Sun’s light comes from the south in the Northern Hemisphere and from the north in the Southern Hemisphere. A wrong azimuth angle could reduce the energy output of a solar PV up to 35%. Quite a lot! Luckily, our system designers tend to use an azimuth of either zero or facing the Equator to avoid any issues. We’re proud to have nerds on our team.
How Solar Power Works, On-Grid, Off-Grid And Hybrid
Martin Newkirk
The three main types of solar power systems
1. On-grid - also known as a grid-tie or grid-feed solar system
2. Off-grid - also known as a stand-alone power system (SAPS)
3. Hybrid - Solar plus battery storage with grid-connection
Simplified layout of a on-grid solar system
First we will describe the common components of the three types before going into more detail about the different systems and how they work.
All Solar Systems Include:
Solar panels:
Solar panels or solar modules are installed together in what is known as a solar array. Modern solar panels are made up of many solar cells or photovoltaic (PV) cells which generate direct current (DC) electricity from sunlight or energy from the sun. Note: It is light energy or irradiance, not heat, which produces electricity in photovoltaic cells.
Solar inverter:
Solar panels generate DC electricity which needs to be converted to alternating current (AC) electricity for use in our homes and businesses. This is the role of the solar inverter. In a string inverter system, solar panels are linked together in series and the DC electricity is brought to a single inverter which converts the DC to AC. In a micro inverter system, each panel, or every two panels, has it’s own micro inverter attached to the back side of the panel. The panel still produces DC, but is converted to AC on the roof, and is fed straight to the electrical switchboard.
Switchboard:
(electricity consumption.) AC electricity is sent to the switchboard where it is directed to the various circuits and appliances in your house that are using electricity at the time. Any excess electricity is sent to either a battery storage system if you have a off-grid or hybrid system, or to the electricity grid if you have an on-grid system.
1. On-Grid System
On-grid or grid-tie solar systems are by far the most common and widely used by homes and businesses. These systems are connected to the public electricity grid and do not require battery storage. Any solar power that you generate from an on-grid system (which is not used directly in your home) is exported onto the electricity grid and you usually get paid a feed-in-tariff (FiT) for the energy that you export.
Unlike hybrid systems, grid-tie solar systems are not able to function or generate electricity during a blackout or power outage due to safety reasons; since blackouts usually occur when the electricity grid is damaged. If the solar inverter was still feeding electricity into a damaged grid it would risk the safety of the people repairing the fault/s in the network. However most hybrid solar systems with battery storage are able to automatically isolate from the grid (known as islanding) and continue to operate during a blackout.
Batteries are able to be added to an on-grid solar system at a later stage if required. The popular Tesla Powerwall 2 is an AC battery which can be added to an existing solar system.
In an on-grid system, this is what happens after electricity reaches the switchboard:
- The meter. Excess solar energy runs through the meter, which calculates how much power you are either exporting or importing (purchasing).
- Metering systems work differently in many states and countries around the world. In this description I am assuming that the meter is only measuring the electricity being exported to the grid, as is the case in most of Australia. In some states, meters measure all solar electricity produced by your system, and therefore your electricity will run through your meter beforereaching the switchboard and not after it. In some areas (currently in California), the meter measures both production and export, and the consumer is charged (or credited) for net electricity used over a month or year period. I will explain more about metering in a later blog.
- The electricity grid. Electricity that is sent to the grid from your solar system can then be used by other consumers on the grid (your neighbours). When your solar system is not operating, or you are using more electricity than your system is producing, you will start importing or consuming electricity from the grid.
2. Off-Grid System
An off-grid system is not connected to the electricity grid and therefore requires battery storage. An off-grid solar system must be designed appropriately so that it will generate enough power throughout the year and have enough battery capacity to meet the home’s requirements, even in the depths of winter when there is less sunlight. The high cost of batteries and inverters means off-grid systems are much more expensive than on-grid systems and so are usually only needed in more remote areas that are far from any electricity grid. However battery costs are reducing rapidly, so there is now a growing market for off-grid solar battery systems even in cities and towns.
There are different types of off-grid systems which we will go into more detail later, but for now I will keep it simple. This description is for an AC coupled system, in a DC coupled system power is first sent to the battery bank, then sent to your appliances. To understand more about building and setting up an efficient off-grid home see our sister site go off-grid/hybrid
- The battery bank. In an off-grid system there is no public electricity grid. Once solar power is used by the appliances in your property, any excess power will be sent to your battery bank. Once the battery bank is full it will stop receiving power from the solar system. When your solar system is not working (night time or cloudy days), your appliances will draw power from the batteries.
- Backup Generator. For times of the year when the batteries are low on charge and the weather is very cloudy you will generally need a backup power source, such as a backup generator or gen-set. The size of the gen-set (measured in kVA) should to be adequate to supply your house and charge the batteries at the same time.
3. Hybrid System
Due to the decreasing cost of battery storage, systems that are already connected to the electricity grid can start taking advantage of battery storage as well. This means being able to store solar energy that is generated during the day and using it at night. When the stored energy is depleted, the grid is there as a back up, allowing consumers to have the best of both worlds. Hybrid systemsare also able to charge the batteries using cheap off-peak electricity (usually after midnight to 6am).
There are also different ways to design hybrid systems but we will keep it simple for now.
- The battery bank. In hybrid system once solar power is used by the appliances in your property, any excess power will be sent to your battery bank. Once the battery bank is full, it will stop receiving power from the solar system.
- The meter and electricity grid. Depending on how your hybrid system is set up and whether your utility allows it, once your batteries are fully charged excess solar power not required by your appliances can be exported to the grid via your meter. When your solar system is not in use, and if you have drained the usable power in your batteries your appliances will then start drawing power from the grid.
Simplified layout of a hybrid solar system
Choosing Off-Grid Or Hybrid?
For many people the dream of becoming completely energy independent may be very difficult and expensive. To help you understand whether it is cost effective and what you should know before you decide to build or go off-grid refer to our related off-grid design guide.
For a more detailed explanation of the different hybrid systems and battery options now available see the hybrid/off-grid energy storage review here
