Electrical panels 101: a beginner’s guide to your home’s breaker box
Jess Silber-Byrne
April 25, 2025
•
1-3 min read
- Electric Panels
- Heat pumps
- The Switch Is On blog
Electric Panels
The Switch Is On helps make home electrification easy.
Electric panels
Home electrification projects — like adding a heat pump or heat pump water heater — often require more power, so it’s important to know what your panel can handle.
The best way to keep costs down is to make the most of your existing panel before choosing a bigger one.
Know your electric panel options: optimize, upgrade, or upsize
Replacing or upsizing an electric panel is what many homeowners assume they need, but there are often easier and more affordable options. Here's how to think about your options:
1
Optimize
Make the most of the panel you already have. Connecting tools to your home’s electrical system — like circuit splitters that manage when you use power — and choosing efficient appliances can make this the simplest and most affordable option for many homes.
2
Upgrade
Replace an older panel with a newer model of the same size to improve safety, boost reliability, and add smart features – all while avoiding the higher costs and extra utility demands that come with increasing capacity when you don’t need to.
3
Upsize
If optimizing or upgrading your panel won’t give your home the power it needs, then you might need to upsize. Because this can cost more and often requires extra permitting, it’s best saved as a last option.
Why optimization matters
Understanding your home’s power needs early helps your project run smoothly, avoid surprises, and skip upgrades you may not need.
Save money
Use what you already have and avoid paying for a full panel upgrade.
Save time
Knowing what your panel can handle upfront helps you avoid permitting delays and keeps your project moving.
Simplify projects
Good planning makes your project easier by reducing changes, lowering stress, and keeping installation smooth.
Support grid stability
Using energy more efficiently takes pressure off the grid and helps keep power reliable for everyone.
Making the most of your electric panel
Figure out how much power your home really needs
The key to optimizing your electric panel is understanding your home’s “load”: the amount of power your appliances use at the same time.
Start with a load calculator — it shows how much power your home really needs and what your panel can support. It gives you a quick snapshot of what’s possible before you make big decisions, and often reveals your panel can handle more than you think.
How to reduce your load
Make your home more energy efficient by choosing appliances that use less electricity, like heat pump water heaters and heat pumps that provide heating and cooling in one unit. You can also seal air leaks and improve insulation, lowering how much power your home needs at one time and help your panel support more of your electrification plans.
How to shift your load so your panel can handle more
Tools like smart panels, circuit controllers, and plug sharing devices can shift when your appliances use electricity, helping your panel handle new equipment without being pushed to its limits.
Use a meter socket adapter
What are meter socket adapters?
Meter socket adapters (MSAs) give you another way to support new electric equipment when your panel is tight on space. An MSA sits between your utility meter and your home’s electrical system and provides a safe, direct connection for things like solar, backup power, or EV charging. It’s a good option if you want to avoid the cost or delays of a full panel upgrade.
Who should get one and why?
A meter socket adapter is a good option if your home’s electrical panel doesn’t have room for new equipment and you want to avoid the cost or delays of a full upgrade. It’s designed for homeowners who need a safe, faster way to add more power capacity without replacing their entire panel.
Are you in California?
These California utilities have programs to support the installation of meter socket adapters (MSA). Click to learn more.
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Tools and resources for electric panel optimization
Calculators, videos, and trainings to estimate your home’s power needs and avoid unnecessary upgrades.
Some of these resources are intended for contractors and homeowners with knowledge of electric systems. For final load calculations, always consult a licensed professional.
Each calculator offers its own level of detail – from quick estimates to more precise, electrician-style results. Choose the one that matches where you are in your planning process.
My Electric Calculator
An easy-to-use calculator built for DIYers and professionals.
Try calculator
The Watt Diet Calculator
Redwood Energy provides a downloadable Microsoft Excel file to determine panel size.
Try calculator
Kopperfield Calculator
Professional-grade calculator with in-depth estimates. Built for electricians.
Try calculator
Palmer Electric Calculator
A calculator for electricians with instructions for DIY homeowners.
Try calculator
How to determine your panel size
This article from Rewiring America walks through the details of electric panel sizing.
Read article
Need help? Find a contractor
A licensed professional can provide detailed electric load calculations for your home.
Find a pro
Frequently asked questions
Wondering whether your panel can support new electric appliances or if you’ll need an upgrade? These FAQs explain the key choices, tools, and steps to help you move forward confidently.
Want to know what your electric panel can handle?
Connect with a contractor to find out how much power your home needs and which optimization or upgrade option is right for you.
We develop our content in partnership with our coalition members and other organizations. It is this collective expertise that is reflected throughout our website.
Funding for this page is part of California Climate Investments, a statewide initiative that puts billions of Cap-and-Invest, formerly known as Cap-and-Trade, dollars to work reducing greenhouse gas emissions, strengthening the economy, and improving public health and the environment — particularly in disadvantaged communities.
TECH Clean California is a statewide initiative accelerating the adoption of clean water and space heating technology across California. It provides market incentives and workforce education and training to make it easier for distributors and contractors to stock, sell, and install low-emissions heat pump technology for residential projects.
