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How Does a Solar Generator Work?

Are you looking to make the switch to solar power? If you live in an area prone to natural disasters or blackouts, you will want solar energy to prevent power outages. Additionally, renewable energy sources save money, keep you off-grid, and are often portable.

One of the easiest ways to harness the sun’s power is using a solar generator. But what exactly is a solar generator? And how does it work? Keep reading to learn all about solar generators.

solar generator

What Is a Solar Generator?

A solar generator works with solar panels to provide backup power. It is an electronic box with an inverter, batteries, and a charge controller. Attached to the generator are solar panels. These capture the sun’s radiation and store it. 

The solar radiation travels from the battery to the inverter, where it gets converted to alternating current (AC) power from direct current (DC). The inverter then releases the energy into your house as electricity.

Solar generators are eco-friendly since they do not rely on fossil fuels. They do not release greenhouse gas emissions, which can lessen your carbon footprint.

How Does a Solar Generator Work?

A charge controller connects the solar panels to the battery. The solar panels get oriented in the optimum position to maximize solar irradiance. This position depends on the time and location. You can estimate the solar power your panels receive with this calculator.

Upon sunlight exposure, the solar panels generate DC power. The voltage produced may vary from 12-18V, depending on the panel’s surface quality and solar irradiance. The solar power flows from the panels to the charge controller. If the voltage produced by the panels exceeds 13V, the charge controller transfers it to the battery.

Initially, the battery converts variable DC power into a more stable state. Once the battery fills, the charge controller stops transferring power. The current from the charge controller generates a chemical reaction within the battery. The product from this reaction is potential chemical energy.

When you connect a load to the battery, the reaction gets reversed, and the potential chemical energy becomes electrical. The direct current exiting the battery goes to the inverter. The inverter converts it to an alternating current.

Some appliances only require DC power, so you may not need the inverter. However, it’s a good idea to have an inverter for high voltage applications.

Components of a Solar Generator

We’ve covered the basics of how a solar generator operates. Let’s explore the individual components.

Solar Panels

Solar panels collect solar radiation and convert it into DC power. They feature semiconductor materials like silicon typically laid on a polymer back-sheet, protected by glass, and surrounded by a metal frame. The cells in the panel have electrons that get moved by photons from sunlight. These electrons enter a circuit and produce energy. 

There are several types of solar panels, including:

  • Monocrystalline
  • Polycrystalline
  • Concentrator photovoltaic (CPV)
  • Thin-film
  • Bifacial
  • Double glass

The amount of power each generates depends on the size and solar irradiance at that time.

Monocrystalline panels are some of the oldest types, but they are highly effective. You can make the photovoltaic (PV) cells in a monocrystalline panel by slicing ingots of pure single-crystal silicon. The resulting pieces have a uniform crystal structure that adds durability and increases the amount of sunlight each cell can capture. Monocrystalline solar panels can have up to 25% efficiency and operate at higher temperatures, but they are costly.

Polycrystalline panels involve fragments of multiple silicon crystals that you melt together. As a result, the PV cells have an uneven blue coloring. The molten silicon can undergo two processes:

  • Edge-defined film-fed growth
  • Shaping into ingots and cutting into wafers

Polycrystalline solar panels do not have uniform crystal structures, making them less durable and efficient. Efficiencies generally range from 12-16%. However, they are more affordable than monocrystalline panels.

You can find CPV panels in industrial solar farms. They have mirrors, lenses, and trackers to capture the most solar power. These added components significantly boost their efficiency (up to 46%), but they need frequent maintenance. Since they use multi-junction cells with multiple layers of semiconductor material, they capture light from more parts of the spectrum.

Thin-film solar panels employ a thin layer of semiconductor materials applied on a surface. They work on ceramics, polymers, and metals, expanding their applications. While relatively inefficient (7-13%), they can go almost anywhere. The most common types are amorphous silicon, copper indium gallium selenide, and cadmium telluride. Keep in mind that cadmium is a toxic substance.

Bifacial panels can be either monocrystalline or polycrystalline. They absorb solar power on the top and bottom surfaces, increasing their efficiency by 30%. You would need to install them on a reflective surface with a high albedo and tilt them to absorb the most irradiance on both sides.

Double glass panels feature PV cells kept in place by two glass layers. The glass gets heat-treated to reduce reactivity and degradation rates, which improves durability. One can combine double glass and bifacial technology as well. They are less costly to produce, but they require high skill levels to install.

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Battery

Without a battery, you would only have solar energy on sunny days. When you don’t have much solar irradiance, a battery can serve as a power source. It stores excess power produced by the panels as chemical energy. When you need more electricity, the battery converts the chemical energy back into electrical energy by undergoing a chemical reaction.

Usually, solar generators come with lithium-ion batteries. While you may find some lead-acid batteries, Li-ion is more effective and affordable. Many come with a 12V rating. The panels used in the system are usually around 18V to power the 12V batteries.

Charge Controller

Charge controllers connect the solar panels to the battery. They stabilize the current from the PV cells, making it uniform for the storage system. In a system with an 18V solar panel and 12V battery, the charge controller drops the voltage to 15V to make it safer for the storage system. These devices protect the battery from overcharging, preventing the current from flowing back to the panels.

Inverter

Inverters convert the low voltage DC power to high voltage AC power. This device lets the solar generator power AC devices in a house. When the load demands DC power, the current will bypass the inverter.

Most devices use AC power, making the inverter an integral part of the generator. However, some fans and LED lights can run on DC. Most solar generators have DC ports to operate these appliances directly. Regardless, you will want an inverter for the devices that require higher voltage power.

Types of Solar Generators

There are three kinds of solar generators used in residential applications. Here we will dive into each type.

Solar Backup Generators

Solar backup generators store emergency backup power during an outage. They have a higher capacity than standard generator batteries, with some having multiple batteries for extra storage. These generators power essential devices like computers, mid-range appliances, and lights. Usually, they have multiple AC outlets. 

These are some of the most efficient generators available. Depending on the wattage of your solar panels, you can charge the generator within a couple of sunny days. These generators are silent and clean so that you can keep them in your house.

However, these generators are heavy and expensive. Once you invest in solar power, your system should last for many years.

Portable Solar Generators

Portable solar generators use low-wattage solar panels and lightweight components that you can take with you on camping trips. They provide small amounts of power, but they can sufficiently supply small appliances, smartphones, lights, and laptops. Also, you can charge these generators with a car adapter or AC outlet.

These generators aren’t very useful outside of outdoor applications. They take a long time to charge, and they cannot power high voltage devices for long. Nevertheless, you can carry them easily and use them on the go.

Solar Generator Kits

Solar generator kits combine all of the aforementioned components in one purchase. They take the guesswork out of determining which devices are compatible, so you can have a functioning generator upon receiving the parts. Also, they have manuals and convenient packaging to expedite the installation process.

The components usually have the same manufacturer, which can improve your customer service experience for a malfunctioning part. Furthermore, the parts are less likely to fail as the charge controller should effectively prevent the battery from overcharging.

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Costs of Solar Generators

The cost of a solar generator varies drastically based on its size and capacity. According to the US Energy Information Administration, the average cost has fallen significantly over the years. As of 2019, a solar generator will cost approximately $1,796 per kilowatt of annual output to install. Depending on the type of semiconductor used, the price can change as such:

  • Fixed tilt crystalline silicon: $2,242/kW
  • Axis-based tracking crystalline silicon: $1,497/kW
  • Fixed tilt thin-film cadmium telluride: $1,537/kW
  • Axis-based tracking thin-film cadmium telluride: $1,962/kW

However, the prices drop dramatically for small solar generators. These can cost $125-$500, with battery capacities ranging from 150 Wh to 500 Wh. If you want a portable generator for occasional use, aim for one of the small sizes.

If you want some home backup power or to live off the grid, consider a mid-sized generator. These range from 750-2,000 Wh battery capacities, and they cost around $1,500-$2,000.

For those who want a full home backup, you’ll need a powerful and large solar generator. These can last you days to months before needing to recharge. You’ll want something with at least 2,000 Wh of battery capacity. For more power, stack multiple batteries to expand the capacity. These generally cost between $3,000 and $5,000.

Pros and Cons of Solar Generators

Now that you know more about solar generators, let’s compare their advantages and disadvantages.

Pros

Here are some of the benefits of solar generators.

Free fuel from the sun

Fossil fuel generators need you to buy fuel whenever you want to power. With a solar-powered generator, you can get free fuel whenever the sun comes out. This aspect lowers operating costs significantly, which can save you plenty of money in the long run.

Generating energy using oil costs 8.09 cents/kWh. You would spend 2.21 cents/kWh for coal power, and natural gas costs around 7.51 cents/kWh. Compared to spending nothing for one kWh of solar energy, you end up saving a significant amount of money.

Clean, renewable energy

Solar power does not burn fossil fuels, so you have a clean source of energy that protects the environment. This carbon zero fuel source does not emit greenhouse gasses, and it lowers your carbon footprint. Also, you can continue getting energy even if the fossil fuel reserves become empty.

Diesel fuel consumption produces about 432 million metric tons of CO2 each year in the United States. That accounts for approximately 9% of the total carbon dioxide emissions of the country. According to the National Renewable Energy Laboratory, coal power contributes to about 1,000 grams of CO2/kWh. Oil energy equates to around 825 g CO2/kWh, and natural gas is about 500 g CO2/kWh. On the other hand, photovoltaics produce around 50 g CO2/kWh.

Besides CO2, fossil fuels produce other greenhouse gases like nitrogen oxides, sulfur, and methane. None of these are produced through solar energy.

Overall, solar generators produce a cleaner and safer energy source for you and the environment. Another benefit of having clean energy is that you can keep your generator inside your house.

Quiet and low maintenance

Solar generators are nearly silent. They do not have many moving parts, which significantly reduces the noise levels. Some have cooling fans that turn on while in use, but these produce far less noise than a traditional diesel generator.

At the most, cooling fans will produce 50 decibels of sound. On the other side of the spectrum, gas generators have nose levels between 68 and 100 decibels. This sound level could lead to hearing damage with extensive exposure.

Seeing as normal conversation and air conditioner operating volume levels are around 60 decibels, a solar generator will not cause much disturbance in your home. Also, you could store it outside if you never want to hear it.

Since there are few moving parts, solar generators are less likely to break compared to the standard options. You will spend less on maintenance costs, as long as you keep the panels clean and perform regular inspections.

Cons

Despite all of the benefits for your household and the environment, solar generators have a few drawbacks.

High upfront costs

On average, solar generators cost about twice as much as gas generators. While you will save money over its lifetime, the payback period is about five to eight years. Despite the high capital costs, there are lower operating costs because of the free fuel supply and minimal maintenance. 

Regardless, you need to invest a lot upfront to have access to this technology. One of the biggest barriers to the further implementation of solar power is the capital cost. In addition to the price of the components, you may need to redo the infrastructure to accommodate for the solar panel array needed to supply sufficient power.

Slow recharging

Since solar PV cell arrays rely on a steady supply of sunlight, recharging takes a long time. If you experience a period of cloudy weather, it can take many days to charge your batteries. Also, the recharging time depends strongly on your location, time of day, and season. Someone who lives in a dark, shady area with low sunlight would probably not benefit from solar power.

Contrarily, you can recharge a fossil fuel generator whenever you want for immediate power. All you need to do is go to a gas station, fill up a fuel tank, and you’re all set to energize your house. Gas power is more efficient as well.

Limited power supply

Depending on the size of your battery, you can only generate a specific amount of power at once. Unless you live in a small house, one battery probably won’t fulfill your power needs. You can get multiple batteries to stack together, but this can drive up the cost.

If you plan on using solar power to charge devices and run small appliances for short periods, a small battery should work for you. Otherwise, you might find a gas generator more adequate for your household needs.

Keep in mind that while you will only have a small amount of power at your disposal, there is still a finite amount of fossil fuels. They may seem more widely available in the short term, but the world will run out of these resources before the sun stops shining. According to the US Department of Energy, we will run out of fossil fuels in 50-120 years. On the other hand, the sun won’t start to die for another 2 billion years.

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