How to electrify on a 100 Amp panel

Smart splitters and smart panels

Cool new technology exists that can pause unnecessary circuits to avoid overloading your panel. 

Smart splitters (like the splitters from DryerBuddy, SplitVolt, or NeoCharge) are quite simple and low-cost ($400-$700). Some are plug-based and DIY, while others are hard-wired and require an electrician to install. These are best when you are nearly able to fit everything on your existing panel and just need some support for that last device. For example, if your clothes dryer is near where you park your car, you can use a smart splitter to share a circuit between your clothes dryer and EV charger. How often do you need to dry a load of laundry and charge your car at exactly the same time?

Smart panels (like the ones from Span or Koben) are a more expensive solution ($3,000–$5,000 plus installation by a qualified electrician), and they are also the most sophisticated and comprehensive. Smart panels can allow you to manage all of the loads on your electrical panel, which enables you to optimize the use of solar or batteries. For example, if you have a home battery system, you can choose which circuits stay on in a power outage to maximize your back-up power. We wrote a lot more about our love of smart panels here.

15 Amp or 120 Volt heat pump water heaters

Standard heat pump water heaters use 240 Volts and 30 Amps of electrical power, but you can also select a 15 Amp model to free up panel space. If you live in a moderate climate or if your water heater is indoors, new 120 Volt heat pump water heaters may be the easy install solution for you. On top of being power-efficient, these 120 Volt devices don’t need a new circuit, which can save you over $1,000 on installation costs! 

As long as you get a water heater that is the right size, you won’t compromise on hot water with a power-efficient choice. If you are happy with your existing water heater, we recommend sizing up by one step when you switch to a 240 Volt heat pump water heater (e.g., 40 gallons → 50 gallons), and by two steps when you switch to a 120 Volt heat pump water heater (e.g., 40 gallons → 65 gallons), just to be sure to get all the hot water you want.

Variable-speed heat pumps

Variable-speed heat pumps (aka “inverter-driven” or “variable-capacity”) make the heating and cooling process more gradual and power-efficient than a traditional system. Unlike a single-speed heat pump, they run at multiple speeds rather than simply having “on” and “off” modes. (Bonus: you’ll also have a more consistent temperature from room to room and throughout the day!)

Heat pump dryers and 120 Volt clothes dryers

Heat pump dryers use much less power and energy to dry your clothes, often requiring only a 240 Volt, 15 Amp circuit — whereas an electric resistance dryer requires a 240 Volt, 30 Amp circuit. 120 Volt condensing combination washer/dryers can be a great choice too, particularly for renters. 

A load of laundry might take an hour and a half to dry with a heat pump dryer, or two hours to dry with a condensing electric dryer, relative to an hour with a standard electric resistance dryer.

If you select the power-smart choices in the table below, chances are you will be able to electrify on an existing 100 Amp panel. If you want to run the numbers for yourself, check out Redwood Energy’s Watt Diet Calculator, and Peninsula Clean Energy’s Design Guidelines for Home Electrification.

Finally, talk to your electrician about your plan to confirm that your selected combination of appliances will allow you to electrify while keeping your existing panel.