Solar and Battery Backup Systems

Drews Solar does not offer battery backup systems at this time. Battery systems are currently a large investment without economic benefit for solar homeowners, and generators are still the top option for backup power. When the benefits or economics of battery systems change, they can be added to a residence and interconnected to an existing rooftop solar array at a later time.

Are Batteries the Right Investment for Your Home?

While battery backup systems are a good choice for some homes, they are currently a large investment for most homeowners. To give you a rough idea of what a battery backup system would look like with Tesla Powerwall batteries: Tesla Powerwall batteries cost about $12,000 to $14,000 installed and hold 13.5 kWh each. Depending on how much electricity your home uses on a daily basis, and how much power you would want available during a power outage, you would likely need between one and four Powerwalls to meet your needs. It is a large investment for the amount of power the batteries would make available in the event of an outage. For most customers, a generator would be a better investment until the cost of battery systems becomes more affordable. Generators also have the added benefit of continuing power supply during a power outage in inclement weather. If the power outage occurs during a winter storm, when snow covers the solar panels, or during a stretch of stormy, overcast weather, the solar panels may not be able to recharge the batteries enough to provide continuous power to the home.

Can Batteries Store my Solar Power for Nighttime Use?

You can, but fortunately, you don’t need to! All Wisconsin utilities bill and meter residential solar customers with net metering. Net metering is a utility billing policy that enables customers who generate electricity from their own solar systems to receive a credit for any energy they export to the grid for use at a later time, such as during the evening or night. When the customer generates more electricity than they use, the excess flows back to the grid and customer receives a credit on their bill for the excess electricity they export to the grid. This credit can be used to offset electricity the customer uses at other times during the billing cycle or year. Some utilities net meter on a monthly billing-cycle basis, others on an annual or indefinite basis, allowing residential solar customers to trade electricity with the grid in a one-for-one basis for a month, a year, or more. Net metering eliminates the economic incentive for homeowners to add battery storage for daily usage; excess solar electricity produced during the day will be used to offset any electricity pulled from the grid at night, essentially treating the utility like a battery.

Planning Ahead for Batteries in the Future

It is possible to install your solar array to be battery-ready. For a small additional cost, we can install a different SolarEdge inverter that can be connected to battery systems. But, we don’t recommend this option unless you plan on adding a battery system in the next couple of years. If you are planning on adding a battery system, in the next five to ten years or more, we recommend installing a new battery-ready inverter at the same time you install your battery system for the following reasons:

  • Not all inverters and batteries are compatible. By installing a battery-ready inverter at the same time you install your batteries, you can choose from all the battery systems available, instead of being locked into choosing between a brand or two of batteries.

  • Battery technology is quickly evolving. By waiting to install a battery-ready inverter at the same time you install your batteries, both your inverter and batteries will have the same level of technology and the most updated systems, so you can be sure your system has the highest levels of efficiency and communication.

If you are Ready to Install an Integrated Solar-and-Battery System Now

For homeowners who are ready to invest in battery systems now, we are able to offer a referral to a Wisconsin-based solar and electrical company with expertise in designing and installing integrated solar-and-battery-backup systems.  Contact us for a referral if you’re interested in further exploring if a battery backup system is right for you and your home.