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A Guide to Main Panel Upgrades (MPUs)

How a part of your home you probably don’t think about can be a big deal when going solar

Some people call it a “breaker box.” Some people of a certain age may still call it a “fuse box.” Electricians may refer to it as the “load center.” Most commonly it’s called the main electrical panel, but most people don’t call it anything at all because they don’t think about it most of the time. Chances are it’s somewhere in your basement or garage or other out-of-the-way part of your house, and maybe you’ve looked at it a handful of times in all the years you’ve lived in your home, on the very rare occasions you had to go reset a tripped breaker.

When you’re in the process of going solar, however, your main electrical panel can suddenly become vitally important. In fact, issues related to the main electrical panel can be one of the biggest factors affecting the cost and timeline for installing a residential solar system. That’s why we decided to dedicate a post on our blog to explaining how main panels, and the potential need to upgrade them, impact solar projects, for the benefit of homeowners considering whether solar is right for them.

What a main electrical panel is and why it matters

Without going into the weeds of technical jargon, the main electrical panel is like a routing hub for all of the electrical power used by your home. Electricity (whether supplied by the utility grid, your solar system, or a combination of the two) enters and is then distributed through the main panel to the various parts of your house to power your appliances, lights, and other devices. This is accomplished by dividing up the home into different circuits, each with a breaker rated by number of amps. If one circuit becomes overloaded – your kitchen, for example – then the breaker trips, shutting off power to the kitchen circuit, while preserving power to the rest of your home and preventing the danger of fire or electrocution. Your main panel also has a main breaker, which can be used to shut down the feed of electrical power into your home entirely.

For everyday home improvements like, say, replacing an old appliance with a new model or adding some new lighting fixtures, it’s usually not necessary to worry about whether your main panel can handle it. Going solar however, is a game-changer – not only for how your family lives, but for your home’s electrical infrastructure as well. If the main breaker of your electrical panel is rated for less than 200 amps (we’ll show you how to check later in the post), there’s a chance that you will need to replace your main panel with an upgraded one in order to install a residential solar system. In some cases on older homes, an examination of the main panel during a solar project may discover that your main panel is an outdated model no longer approved by the local utility, meaning it must be replaced to meet local building codes.

It’s important to understand that this isn’t simply an arbitrary bureaucratic requirement. Inadequate main electrical panels will not be able to handle the load from your solar panels safely, at best keeping your system from working properly and at worst potentially even causing a fire.

Why main panel upgrades can present a “wild card” in solar projects

The first thing to know about a main panel upgrade (MPU) in a residential solar project is that it significantly increases the scope of work. Installing a new main panel may require work from specialists who have training that some solar panel installers lack. In some homes it’s also necessary to relocate the panel, or do extensive rewiring. The additional planning and logistics can cause the installation timeline to increase, sometimes substantially. 

This also means a jump in price. Solar system pricing estimates are typically done by calculating your energy needs based on past consumption and determining your home’s roof area and sun exposure from satellite imagery. While these estimates are usually quite accurate, they’re calculated with no access to information on the state of your house’s electrical infrastructure, like the wiring and main panel. If an MPU is necessary, it’s often not possible to identify it before the site assessment step of the project, where more detailed information is collected about your home by having you send in photos or by having a technician pay a visit in person. An MPU typically costs from $3000 to $5000 – not a huge amount, but still an unpleasant surprise if it wasn’t included in the original estimate for your solar project.

A silver lining to the financial aspect of an MPU is that the additional cost can be claimed as part of your solar investment when filing for the Federal Solar Investment Tax Credit (ITC). This means that you’ll end up paying less for an MPU when done as part of a solar installation that you would tackling an MPU on its own.

Often more troublesome than the added cost, however, are the delays that an MPU can add to a solar installation. An MPU can add complexity to the project from a permitting standpoint. Waiting for permits can already be one of the most frustrating aspects of a solar project, since neither you nor your solar contractor ultimately has any power to speed the process along. An MPU also adds more components which must be ordered, giving the ongoing global supply chain disruptions even greater potential to set back your solar project timeline. In fact, as of the time of writing, electrical main panels are currently one of the most back-ordered items in the entire category. 

What can be done to prevent main panel “surprises” from disrupting your solar install

Take a look at your main panel (blowing away some cobwebs if necessary). In many cases the capacity of the main breaker is clearly printed on or near the breaker itself. There is no reliable rule of thumb and a lot depends on the size of the house, but if the main breaker is rated for less than 200 amps, you may need an upgrade.

If you don’t see a capacity listed, or if you want to be extra sure, ask your Zenernet energy consultant. Our expert consultants can help narrow down the chances of an MPU being necessary during the sales process.

For homeowners who choose to go solar, we’ll ascertain whether or not an MPU will be necessary during the site assessment phase. Most homeowners use our convenient Virtual Site Assessment – based on a few photos you submit, our team can determine the right course of action.

What’s the good news?

Although main panel upgrades can cause headaches in the process of going solar, they shouldn’t be blown out of proportion. 

The typical cost of an MPU is minimal relative to the overall cost of a typical residential solar system. At worst, an MPU might add a year or so to the payoff period of your system – the time it takes for the savings from solar to offset the cost of the system before it becomes pure profit. With the payoff period in most strong solar markets at well under ten years, and the warrantied lifespan of modern solar systems at 25 years or more, the price of upgrading your main panel doesn’t seriously affect the value proposition of going solar.

The permitting, scheduling, procurement, and installation of a new main panel will delay the timeline of a solar installation. This can be frustrating, but again, given the long-term nature of a solar investment, the payoff is almost always worth it. 

The biggest bright side of electrical panel upgrades is that they enhance the peace of mind you get from greater energy independence. Having a modern main panel will be beneficial for handling future changes in your energy needs, like buying an electric vehicle or adding a battery to your solar installation. The work that goes into a main panel upgrade also means that in essence your home has undergone a thorough electrical “audit” and been updated to modern electrical standards – something you might have had to do in the future anyway to bring the home up to code. This should give you confidence that your home and your family are safe from the dangers that outdated electrical equipment can present, and will certainly be a benefit if you ever sell the property. 

If you want to start enjoying more peace of mind and all the other financial and quality-of-life benefits of residential solar, schedule a time to talk with one of our energy consultants today. If you haven’t done it already, follow Zenernet on social media so you don’t miss when we post new solar educational resource articles like this one.

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