On-Grid Rooftop Solar System: Definition, and How it Works
An on-grid rooftop solar system is a solar system mounted on the roof of a building that’s connected to the utility grid. On-grid solar systems, sometimes called grid-tied or grid-connected solar systems, consist of photovoltaic (PV) modules that produce electricity from sunlight for use in homes and businesses. They are grid-tied, meaning the owner is able to rely on the electric grid to provide power when their solar panels aren't producing enough electricity to meet their energy needs. Most PV systems on the market today are on-grid systems.
One of the benefits of on-grid solar systems is that they guarantee a constant supply of power, ensuring that homeowners have reliable electricity even when solar generation is low (such as at night or when there isn’t enough sunlight). Another major advantage of a grid-tied system is that homeowners are able to sell the excess energy they generate back to their utility company. This billing arrangement is called “net metering”, and allows solar customers to receive solar credits for the electricity they generate but do not use. However, one of the drawbacks of on-grid rooftop solar systems is that they don't function at all during blackouts, preventing homeowners from being truly self-sufficient. This is because on-grid systems are designed to automatically shut off during blackouts for safety reasons. On-grid solar systems have no battery backup system, meaning they cannot store excess electricity for use during blackouts, limiting their ability to provide power independently of the grid.
The cost of an on-grid rooftop solar system ranges from $11,000 to $35,000, depending on factors such as the size of the system and the energy demands of the building it is providing power to. Whilst the upfront cost is significant, installing an on-grid solar system is often worth it because of the cost-savings generated over time. It allows homeowners to transition to renewable energy, while still being able to fall back on the electric grid when the solar panels underperform.
What is an On-Grid Rooftop Solar System?
An On-Grid Rooftop Solar System (on-grid solar system) is a common type of photovoltaic (PV) array that generates electricity for homes and businesses. On-grid solar systems are "grid-tied", meaning it’s connected to the utility grid. Unlike off-grid and hybrid systems, on-grid systems do not have a battery for storing solar energy. Instead, they draw electricity from the grid when there isn't enough sunlight and “sell” excess electricity back to the utility company when there is an abundance of sunlight. Most PV systems today are on-grid solar systems.
One of the main advantages of on-grid solar systems is the ‘net metering’ billing mechanism, which enables owners to lower their electricity bills by selling the excess energy they generate back to the electric grid. Net metering credits are calculated by comparing the amount of electricity that the building uses from the grid and the amount of electricity that the solar system sends back to the grid, so the owner only has to pay the difference (their ‘net’ consumption). Net metering saves owners of on-grid solar systems money because it offsets the cost of their electricity consumption with the energy they return to the grid, as well as entitling them to credits on their monthly electricity bill when the amount of electricity that they generate exceeds the amount of energy that they use from the electric grid.
Unlike hybrid and off-grid solar systems, on-grid rooftop solar systems do not include a battery. Instead, they rely on the electric grid for power when the solar system is unable to generate electricity. Solar battery storage is often costly, making grid-tied systems advantageous for providing backup power without the need for an expensive battery setup. In the event of a power outage or insufficient solar production, the on-grid system seamlessly switches to the utility supply. However, a significant drawback of on-grid rooftop solar systems is that they offer only partial energy independence since they lack a solar battery for storing electricity as backup power.
How does an On-Grid Rooftop Solar System work?
An on-grid rooftop solar system is the most common type of photovoltaic (PV) system. Similar to other PV systems, on-grid systems utilize solar panels installed on rooftops to convert sunlight into electricity. Unlike off-grid systems, which operate independently, on-grid systems are connected to the utility grid. They operate by seamlessly switching between using solar-generated electricity and grid electricity as needed. During periods of insufficient sunlight, they draw electricity from the grid. Conversely, when there is an excess of sunlight, they "sell" the excess electricity back to the utility company.
Solar panels are installed on the roof to capture sunlight and generate electricity. These panels are made up of photovoltaic cells that convert sunlight into direct current (DC) electricity. However, DC electricity is not suitable for household use and needs to be converted into alternating current (AC) electricity, which is done by an inverter.
Secondly, the inverter converts the DC electricity from the solar panels into AC electricity, making it suitable for use in homes and buildings. The AC electricity is then sent to the electricity meter, where it is measured before being distributed for use.
Finally, any excess electricity that is generated by the solar panels and not used immediately is sent back to the main utility grid. This excess electricity can then be used by other customers connected to the grid, leading to a more efficient use of solar energy. Net metering, a key feature of on-grid systems, allows for the seamless exchange of electricity between the grid and the solar system. Under net metering, the excess electricity that is sent back to the grid is credited to the owner's electricity bill, reducing the overall cost of electricity. This setup allows buildings to use solar power while remaining connected to the grid, reducing electricity bills and promoting sustainable energy use.
It's important to note that on-grid solar systems do not use batteries to store excess electricity. This means that any excess electricity generated during the day cannot be stored for use at night or during periods of low sunlight. Despite this limitation, on-grid systems offer significant benefits, including reduced electricity bills, increased energy independence, and a lower carbon footprint.
What are the benefits of installing an On-Grid Rooftop Solar System?
There are several advantages of on-grid rooftop solar systems, from the reduction of utility bills to the guarantee of constant power. The main advantage of on-grid solar systems is that they guarantee a steady stream of power, which prevents homeowners from being held to ransom by lack of sunlight or changing weather conditions. Another advantage of on-grid is 'net metering,' a billing mechanism that allows owners to reduce the cost of their monthly utility bill. This is achieved by selling excess energy generated by solar panels back to the electric grid, offsetting the cost of their monthly energy usage. Another key benefit of installing an on-grid rooftop solar system is the excellent return on investment (ROI) because the solar payback period, the time it takes the owner to recoup the initial cost of the system, is much shorter for on-grid solar setups.
More information about the eight main benefits of installing an on-grid rooftop solar system is listed below.
1. Guaranteed Nonstop Power Supply
On-grid rooftop solar systems guarantee a constant supply of power from the solar panels and from the electric grid. Grid-tied solar systems constantly switch between solar power and electricity from the grid, which is important because it saves the owners money on their electricity bills. For example, on-grid solar systems draw electricity from the grid during periods of low sun when the solar panels are producing less electricity and when electricity is expensive during peak demand hours. On the other hand, when the solar panels generate more electricity than the building needs, the excess kilowatts are fed back into the electric grid.
2. Possibility of earning more
Owners of on-grid solar systems are able to sell excess energy they generate back to the electric grid for a reduction on their electricity bill. The process of property owners selling excess energy generated by their solar system back to their utility company is called ‘net metering’. Net metering allows owners of on-grid solar systems to earn money by exchanging the excess energy their solar system generates for credits on their monthly electric bills, which reduces the amount they have to pay.
3. Higher Savings
The amount of energy that on-grid solar systems generate often exceeds the energy needs of the building, so property owners are able to lower their electricity bill by selling the excess energy back to the electric grid. On-grid rooftop solar systems guarantee owners high savings because the payments from their utility companies (for excess energy) cancel out the cost of their electricity consumption. Hybrid and off-grid solar systems store excess energy in solar batteries, rather than returning it to the electric grid for financial compensation.
4. Excellent Investment Returns
Return on investment (ROI) for solar systems refers to the solar payback period, which is the amount of time it takes the owner to recoup the initial cost of the system. On-grid solar systems have a shorter ROI than off-grid solar systems because they are less expensive to install and allow owners to earn money through net metering. On-grid solar systems have lower upfront costs because they don’t include a solar battery, which is the most expensive part of the solar system to buy, so owners are able to recoup its cost quickly.
5. Operates effectively
On-grid solar systems are effective economically because it is much faster to recoup the initial cost of an on-grid solar system than an off-grid solar system. In addition to lower upfront costs, schemes such as net metering and tax reductions save owners of on-grid rooftop solar systems money on their installation. On-grid solar systems operate effectively because they switch between drawing energy from the electric grid and drawing energy from the solar array to guarantee a constant supply of power. Grid outages are the only concern for owners of on-grid rooftop solar systems, as the rules of utility dictate that they are not allowed to generate electricity unless their system includes a battery.
6. Installing is simple
On-grid rooftop solar systems are easier to install than hybrid and off-grid solar systems because they don’t include a battery. On-grid rooftop solar systems are inherently simpler to install than off-grid rooftop solar systems because they include one less component (the battery), but a solid knowledge of electrical wiring is crucial to do so without the help of a solar technician. There is a huge variety of solar racking systems available due to the various system sizes and roof types they have to accommodate, so it is the responsibility of the owner of the on-grid rooftop solar system to choose the right one if they want to install it themselves.
7. Low cost
The cost of solar batteries ranges from $6,000 to $23,000, following the rule that the larger the solar system, the larger the battery that it requires. Solar batteries are expensive, especially for buildings that use enough energy to require two solar batteries, meaning on-grid solar systems that don’t include a battery are significantly cheaper. Additionally, solar batteries are expensive because they have a shorter lifespan than the rest of the components in the solar system, so the owner has to pay to replace the part sooner than the rest of the system. On-grid rooftop solar systems cost less to install because they connect directly to the existing electric grid, meaning the owner doesn’t have to purchase and set up a solar battery.
8. Maintenance is less
Solar batteries degrade faster than solar panels, meaning their lifespan is shorter than the other components in the solar system, so solar battery maintenance is essential to improve their longevity. Solar batteries require a lot of maintenance, like checking the level of the electrolyte, cleaning the air filter, and ensuring that the terminal connections aren’t rusted, so on-grid rooftop solar systems that don’t include batteries are easier to care for. On-grid rooftop solar systems only need to be cleaned between two and four times a year to ensure that no debris builds up on the panels and compromises their efficiency. Most of the dirt that accumulates on solar panels falls off naturally or is rinsed off by rainfall, especially if they are installed at a steep angle on a pitched roof.
What are the disadvantages of On-Grid Rooftop Solar Panel Systems?
On-grid rooftop solar systems are efficient, economical, and easy to maintain, but they are not a perfect solution for all renewable energy needs. On-grid rooftop solar systems limit the owner's 'energy independence' because they commonly lack a solar battery, meaning that the home draws energy from the electric grid during periods of low production. An additional disadvantage of on-grid rooftop solar panel systems is their dependence on sunlight because the amount of electricity they generate during periods of low sun and the amount of money they save owners on their electricity bill both decrease during periods of low sun.
Below are the six main disadvantages of on-grid rooftop solar systems.
- Nonfunctional during grid outages. On-grid solar systems automatically shut off during electric grid outages to prevent energy from back-feeding into the electric grid and endangering utility workers, leaving owners who don’t have a solar battery without any power. On-grid solar systems without a battery are nonfunctional during national power outages because users are unable to draw power from their solar panels, the electric grid, or a solar battery until the electric grid is restored.
- Limited to partial ‘energy independence’. On-grid rooftop solar systems are connected to the electric grid, meaning owners rely on electricity from a utility company when their solar system isn’t generating enough energy. Relying on the electric grid, rather than investing in a solar battery to store excess energy, means the building is limited to partial ‘energy independence’ as it is unable to be fully self-sufficient.
- Completely dependent on sunlight. The benefits of having an on-grid rooftop solar system, like switching to renewable energy and reducing monthly electricity bills, disappear when there’s no sunlight. On-grid solar systems are completely dependent on sunlight, as they are unable to generate energy during periods of low sun which occur during gloomy weather and overnight. On-grid solar systems quickly become obsolete when the peak sun hours decrease in the area where they’re installed.
- Provide no incentive to conserve energy. On-grid rooftop solar systems draw energy from the electric grid when the solar panels aren’t producing enough electricity, so owners are not incentivized to make energy-efficient lifestyle changes like turning the lights off when they’re not in the room and keeping devices off when they’re not in use. Evaluating energy usage, the way that people use electricity on a daily basis is just as important for the climate as adopting solar energy.
- Not feasible for every roof. Not all roofs are candidates for rooftop solar systems. Some roofs are too shaded, meaning they don’t receive enough sunlight to make investing in solar panels worthwhile, while other roofs are too steep for solar technicians to safely install solar panels. Additionally, some roofs aren’t strong enough to support the added weight of solar panels and a racking system.
- Difficult to uninstall. Rooftop solar systems are difficult to remove once they have been installed. Moving a solar system is seldom worth the effort, being that it’s complicated, time-consuming and expensive. It’s better to view the solar system as an addition which increases the value of the property, rather than an item to be moved from place to place.
What is the price range for installing on-grid rooftop solar systems?
The price of an on-grid rooftop solar system ranges from $11,000 to $35,000 depending on factors such as the size of the system, brand of solar panels, type of inverter, quality of installation, and energy requirements. On-grid systems are cheaper than hybrid and off-grid solar systems because they do not utilize a solar battery. The average cost of a 4kW on-grid solar system is about $11,400, whereas a larger 10kW solar system is usually about $28,500.
The cost to install an off-grid rooftop solar system is much higher, largely because of the solar battery, which is an essential component for storing energy. Off-grid solar systems cost anywhere between $20,000 and $100,000, depending on the complexity of the setup and the size requirements.
Is it worth it to install On-Grid Rooftop Solar Systems?
Yes, it is worth it to install an on-grid rooftop solar system. On-grid solar panels provide property owners with a reliable source of renewable energy while allowing them to rely on the electric grid when their solar panels aren't producing enough electricity.
The electric grid serves as the ‘battery’ for on-grid solar systems, because they are able to pull energy from it when the sun is not shining. Owners of on-grid solar systems make money on their setup through net metering, meaning it is faster for them to recoup the initial cost and complete the payback period than owners of hybrid and off-grid solar systems.
What is the difference between On-Grid and Off-Grid Rooftop Solar Systems?
The main difference between on-grid and off-grid rooftop solar systems is their connection to the electric grid. On-grid rooftop solar systems are connected to the electric grid, so they are able to switch seamlessly between energy generated by the solar panels and energy drawn from the grid. On the other hand, off-grid rooftop solar systems are not connected to the electric grid, whether that is a choice made by the property owner or decided by the building’s location, so they rely on batteries to store energy. Hybrid solar systems are grid-tied with a battery, meaning they constantly switch between using energy from solar panels, energy from battery storage, and energy from the electric grid to provide a constant supply of power.
What is the difference between On-Grid and Grid-Tied Rooftop Solar Systems?
On-grid and grid-tied rooftop solar systems are the same thing. On-grid and grid-tied solar systems refer to photovoltaic (PV) systems connected to the electric grid, meaning they switch between energy generated by solar panels and energy pulled from the electric grid so the building always has power. On-grid solar systems are effective because they draw energy from the electric grid when there is no sunlight, and they draw energy from the solar system when electricity is expensive during peak hours.