Two men installing more solar panels on roof.

Adding Solar Panels To An Existing System: A Quick Guide


If you have solar panels on your home, you might be wondering about adding solar panels to an existing system. Will new panels work with your old panels? What about your inverter? Should you add a second solar panel system?

Let’s explore these questions and more so you can determine whether adding a few extra panels to your grid-tied home is right for you.

Why Homeowners Add More Solar Panels To Their Existing System

If you have solar panels already, why would you add more to your system? Below are a few potential reasons.

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Your Energy Needs Have Changed

Many of today’s electrical appliances are far more efficient than the appliances they might replace. But if you’re transitioning from gas for appliances like water heaters, ranges, ovens or dryers, you’ll notice that your electricity usage will increase. Growing families also find that they consume more electricity.

And homeowners who buy electric cars and want to charge them at home will consume significantly more electricity, too.

Adding more solar panels to your array can compensate for consuming more electricity by generating more solar energy. As a result, your electricity bill will be lower.

Your Local Utility Grid Is Unreliable

Extreme weather has impacted utility grids in the U.S. Rolling brownouts can be a concern in some states during hot summer months, while unexpectedly harsh winters cause some grids to lose power for days. Adding solar panels with backup batteries, which we’ll cover later on, can allow homes to keep electrical appliances running in these situations.

Solar Technology Has Advanced

If you have an older solar system, it likely generates less electricity than when it was installed. Also, aging systems aren’t as efficient as more current systems, which capture energy faster and utilize it more effectively.  

Adding modern, more efficient PV modules could boost your solar energy generation without too much expense.

Is Mixing Solar Panels OK?

If you want to add more solar panels to your photovoltaic (PV) system, it’s best to go with the same brand and model. That way, you can ensure compatibility of all your renewable energy components.

But what if your current panels aren’t still in production? In that case, mixing solar panels should be OK. You’ll just need to be certain the panels’ voltage, wattage and amperage are a close match. While your original installer is worth consulting, a new solar installer should be able to help you determine the right solar panels to update your system.

Will I Need A New Inverter If I Add More Solar Panels?

Inverters are a key part of your solar system – they convert direct current (DC) electricity produced by solar panels into alternative current (AC) that your home and its appliances can use.

Many solar homes have central or string inverters, which take energy from all the panels and convert the current. When your solar contractor designed your system, they matched the inverter to the power output of the solar panels. Adding more panels may exceed your inverter capacity.

If your inverter can’t handle the additional power, you have a few options, which we’ll cover next.

Get New Solar Panels That Use Microinverters

Microinverters are small inverters installed on each solar module. They convert the DC to AC right at the panel. They’re more expensive than string inverters, but they can be a solid option for adding solar panels to your original system without updating your existing inverter or adding a new one.

Update Your Inverter

It’s also possible to add an entirely new inverter to your PV system to handle the additional power. If you’re only adding a few panels or replacing older panels, you may be able to use your existing inverter. A solar installation company should be able to provide guidance.

Install A Second Solar System

Installing a second photovoltaic system could be the most straightforward approach. It allows you to take advantage of the latest technology while also maintaining a separate warranty for the new components. You’ll also have separate inverters, panels and racking hardware if you install a new system.

It may also be possible to claim additional rebates or incentives from government agencies and utilities. Note that not all systems or upgrades will be eligible.

Adding a second solar array comes with a few caveats. You’ll need enough roof space for installing racking and more panels, for instance. And your new solar system will likely need an inspection and approval from your utility company and local government before being commissioned and going live.

Get An Estimate

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How Much Does It Cost To Add Solar Panels?

The cost of adding solar panels to your system depends on how you approach the upgrade and the other components your project requires. In January 2022, the average cost for a new system was $2.77 per watt, but if you can add panels without updating your inverters, you might be able to lower your per-watt cost.

Still, using the cost for a new system is a good benchmark that can help you budget for adding to your system.

Will New Panels Require Permits, Inspections Or Approvals?

If you want to add more solar power to your existing panels, it might require permits, inspection and approval from local government agencies and your utility company. Policies for PV systems vary by location. Working with an established solar company will help you navigate regulatory hurdles.

Permitting and other regulatory requirements might also depend on how much you’re adding to the old system. These requirements, in addition to the technical skills required to add solar panels, make it difficult for solar homeowners to perform this upgrade as a DIY project.

Adding Batteries To An Existing Solar System

While you’re adding to your system’s capacity, you might consider adding backup batteries. Let’s see what solar energy storage batteries can offer.

Power During Outages

With a properly configured battery bank, it’s possible for you to keep your home powered during outages. Extreme weather, grid overload and simple human error can cause outages.

Most grid-tied solar systems stop powering homes during outages. That’s a safety precaution for utility workers. Solar companies can design a system that uses batteries and insulates your home from the grid, allowing you to maintain power.

Protection From Peak Usage Prices

In many cases, residential and commercial customers who use solar power to generate their own electricity can use a system called net metering if its available in their area. Net metering simply means that you can sell the electricity that you don’t use back to the grid – effectively adding a credit on their electric bill. On these types of grid-tied power systems, however, you may also pay a higher rate for electricity consumed during peak hours, which are the times of the day with the highest overall electricity demand. This is sometimes called time-of-use (TOU) billing.

Homeowners can reduce their dependence on the more expensive peak hour electric service by using their battery banks during these times, which can reduce their electric bill significantly.

The Bottom Line: Adding Solar Panels Can Be A Good Long-Term Investment

If you’re consuming more electricity than when you first installed your solar panels, adding to your system can offset the additional usage. With the right help from a solar professional, you can navigate the technology and regulations to find the best options for generating more renewable energy. You might even discover that you’re still eligible for tax rebates or other incentives.

Ready to update your system to match your electricity needs? Let’s discuss boosting your home’s solar power.

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