Even if the solar system is designed to generate all the electricity in the house, it is possible that energy needs will change over time. Perhaps residents now drive electric vehicles and use more electricity because they have a home electric vehicle charging station . Some homeowners are switching to electric space heating with heat pumps, increasing electricity consumption. But is adding solar panels to an existing system an option?
It is not uncommon for solar system owners to want to expand their panels. If the solar energy system does not produce 100% of the home’s energy, and there is room on the roof for more panels, expanding the system makes sense. In other cases, simpler modifications, such as trimming the tree shading the roof or adding power optimizers, can be another way to increase solar energy production.
Can solar panels be added to an existing system?
Yes, it is possible to expand most solar energy systems, but for various reasons it is not always cost-effective. In some cases, adding solar panels can be more complicated and expensive than you might think, but it is usually feasible.
Adding solar panels to the roof of a house may involve modifying or adjusting parts of the original system configuration. For example, if the system has a string inverter and no additional power, the inverter will need to be supplemented or upgraded. If the system is ground-mounted, another racking system may need to be added. If the homeowner wants to add a battery bank and solar panels, a larger inverter may also need to be installed.
Evaluate the number of solar panels being added to the home.
Just as photovoltaic installers size systems based on household electricity consumption, the same is necessary when expanding an existing photovoltaic system. First, start by assessing the energy bills for the home since the contractor installed the solar panel system.
Next, determine whether your customers are planning to increase their electricity consumption. Common reasons why a home’s electricity consumption may increase include:
- Purchase of an electric vehicle and installation of a home electric vehicle charging station
- Replacing a gas water heater, dryer or stove with an electric model
- Installing heat pumps and replacing or displacing an existing natural gas or propane heating system
Sometimes homeowners can take simple steps to reduce energy consumption. For example, adding water-saving showerheads reduces hot water consumption. If they have an electric water heater, this can reduce electricity bills. Similarly, replacing inefficient appliances or electric heaters can help save energy.
Considerations before adding solar panels to an existing system.
While it is usually feasible to expand a solar system, it is important to think through the entire process well before doing so. Here are some of the most important issues to consider during the planning stage.
Available roof space for solar panels.
It is certainly easiest to add solar panels if there is extra space on the roof; however, there are ways around this. If there is no available space due to existing panels, it is possible to place additional panels on the roof of a garage, shed, shed or ground mount. However, the number of panels may be limited by available space.
Solar inverter upgrade.
Please determine the capacity of the string inverter and see if it can handle additional solar panels. If not, it will be necessary to replace the old inverter.
If your solar system is equipped with microinverters, upgrading is a bit easier. Systems with microinverters have a small inverter mounted on the bottom of each solar panel. Instead of replacing the daisy-chain inverter, simply install more microinverters on the new solar panels.
Permit requirements for solar installation.
Permit requirements for a photovoltaic installation will vary depending on whether you are replacing a photovoltaic inverter, whether you will need to install a pole mount , and local photovoltaic permitting requirements. However, the expansion of your photovoltaic installation may require you to obtain a new photovoltaic installation permit in your jurisdiction to demonstrate your system’s compliance with applicable electrical and building codes.
It is also possible that the authority having jurisdiction (AHJ) will require modification of the existing system to meet current solar code requirements if you add solar panels. Changes to the National Electric Code (NEC) now require rapid shutdown at the module level, which may not have been required when the solar system was first installed.
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Net Metering.
Typically, you will need to notify the utility when you expand your solar PV system in order to update your interconnection agreement. Keep in mind, however, that changes in net metering programs may affect how utilities compensate your customers for excess electricity delivered to the grid.
Solar battery storage.
As the price of home energy storage systems has dropped dramatically over the past decade, many homeowners are looking to add battery storage to their photovoltaic systems. If you are also adding solar panels, now may be a convenient time to add battery storage. Depending on the type of battery you use, you may need to install a new inverter. For example, the Tesla Powerwall 2 has its own built-in inverter and is an AC-coupled solar battery.
Aesthetic considerations.
Consider how the expanded system will look and try to match the appearance of the panels as much as possible. In some cases, you may be able to install the same or a very similar model of photovoltaic modules, even if the output of the solar panel is slightly different.
If not, find solar panels with a similar appearance. If the original solar panels are polycrystalline and have a blue color, adding monocrystalline panels with a black appearance may look strange. If the original panels have a silver frame, avoid installing all-black panels with a black frame, as they will stand out.
Future electricity bills.
In many regions, customers will not be compensated by the power company for the excess energy they supply to the grid over household consumption. For example, most power companies do not compensate customers at the retail rate for energy in excess of the number of kilowatt-hours consumed by a household in a year. This means that a PV system can offset consumption through bill credits, but these credits often expire after a year.
This means that oversizing a photovoltaic system usually does not result in greater savings on energy bills. Therefore, it is important not to oversize the system, otherwise the additional output will not provide additional benefits to your customers.
Age of the existing photovoltaic system.
If your solar system is older than a certain age, usually around 10-15 years, it may be more cost-effective to start over than to expand. Older systems may have outdated components that are less efficient at generating solar power and may require costly upgrades to accommodate additional solar panels. In addition, older inverters or other equipment may not be able to handle the increased load resulting from the additional panels, leading to decreased performance and potential reliability issues.
Quality of the original photovoltaic system.
Many PV installation companies are reluctant to add new panels to an old system, especially if they are not the original installer. They may be concerned about voiding the warranty on the photovoltaic equipment, regulatory violations, wiring errors or poor installation quality. If your photovoltaic company did not install the original photovoltaic panels, it is important to consider what problems you may encounter.
Solar incentives when adding solar panels.
Unfortunately, most homeowners will not qualify for incentives when expanding their solar systems. For example, they probably won’t be able to claim another federal tax credit. It is very important to talk openly with customers about this topic so that they understand the incentives before deciding to expand their solar system.
There are exceptions to this rule, however, and it is helpful to research local incentives, if applicable, to determine whether your customers will qualify, as there may be some options available.
When is adding more solar panels a bad idea?
Installing more solar PV panels on an existing system may be a bad idea if a customer’s installation is already meeting their energy needs, there is not enough space on the roof, or local regulations or incentives make further expansion difficult. In addition, if the cost of adding solar panels to an existing system exceeds the potential savings on energy bills, it may not be financially beneficial. Please evaluate your client’s energy goals, space constraints, solar regulations, incentives and financial considerations before deciding to add solar capacity.
How much does it cost to add solar panels to an existing system?
The cost of adding solar panels to an existing system can vary depending on several factors, including the size of the additional installation, the type and quality of panels, any necessary upgrades to the existing system, labor costs and local regulations. On average, homeowners can expect to pay between a few and tens of thousands of dollars for this type of upgrade if they are only adding solar panels and not battery storage.
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Alternatives to adding solar panels to an existing system.
If a homeowner expresses interest in expanding their photovoltaic system, it is important to know why. This will help determine whether adding photovoltaic panels is the best option.
Adding power optimizers to photovoltaic panels.
Alternatively, if your photovoltaic system has a daisy-chain inverter and no power optimizers, you can increase solar power production by adding them. This is particularly useful for shaded roofs or panels with different orientations.
Reducing shading of solar panels.
If the roof is shaded, can this be reduced? Sometimes trimming a few tree branches can significantly increase energy production. In other cases, solar panels are shaded by other buildings or dormers and this cannot be avoided.
Replacing existing solar panels.
If there is not enough space to add more solar panels and they have an older system, existing solar panels can be replaced. The efficiency of solar panels has increased significantly over the past decade. For example, if your customer has 250-watt solar panels, you can replace them with 450-watt modules.
Add a solar battery.
While this won’t increase the system’s total solar production, adding a backup battery will allow homeowners to have electricity during power outages and during peak sunlight hours. Even if you do not have the ability to expand your solar system, you can add a battery instead. If your customer lives in an area with time-of-use electricity rates, a solar battery can significantly increase savings on utility bills.
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Please consider all factors before adding solar panels to your existing solar system.
If you have homeowners who are looking to go net-zero and currently are not, expanding your current system by adding solar PV panels can be a great option. Adding solar panels is feasible for many households, although it may involve installing photovoltaic modules in another location, such as the garage roof.
Expanding an existing photovoltaic system can be expensive, and many homeowners cannot take advantage of solar incentives. Please make sure your customers understand whether they are eligible for the rebate so they can make an informed decision.