How Many Solar Panels to Run a House?

Choosing 100% Solar Powered Lifestyle

Living in a 100% solar powered home is an environmental dream with a tiny carbon footprint. Ideally, the amount of power produced is adequate to support your current power consumption lifestyle. With the development of energy efficient appliances and consumption conscious programming, modern technology has made that dream a potential reality.

Creating Connections

Solar living can be divided into two basic groups, Grid Tied or Off Grid systems.

Grid Tied

Grid Tied systems are connected to the local power company. The electricity that you create is inverted for home use, and the excess becomes part of the ongoing flow of electricity being produced by the power company and any other fellow "solarists" who are also tied into the grid.

The amount of electricity that is produced and consumed by grid tied users is monitored by the power company. In many cases, the cost of electricity consumption is offset by the excess production, thereby reducing or (ideally) eliminating an electric bill. The local power company may limit how much power you are allowed to produce, or receive credit for, on a grid tied system.

Off Grid

Off Grid systems are stand-alone systems that are used to supply 100% of a home's electricity without any outside support. They are nearly always connected to a gas fueled back-up generator for emergency use. A bank of batteries stores energy for use at night or when solar power is not being generated.

Off-grid systems require the use of a charge controller to maintain the quantity of power entering the system to prevent overloading of batteries or breakers. Like their grid tied counterparts, they also utilize inverters that convert the solar electricity from DC to AC for home use. (Read More: Home Battery Backup Solutions)

Math And Electricity Under The Sun

The quantity of solar panels required to maintain your current power consumption lifestyle varies hugely, based on a number of factors. The size of your home and family, the types of activities you participate in, and the times of day your activities occur are just the beginning.

Calculations regarding your household's electricity requirements start by looking at your power bill. The power company should be able to supply you with a statement for the last year, with a monthly breakdown of the kilowatts used. Some companies also supply a "time-of-day" graph to show when your average peak use times occur.

If you are not able to reference these statistics, there are general consumption guidelines designed to provide average numbers on which to base your calculations.

Geographic location will determine the amount of sunlight that is available under optimal circumstances, as well as creating specific environmental situations that may have a profound effect. The length of day, angle of the sun, and number of sunny -versus- cloudy days determine how much energy can potentially be produced.

The use of a tracking device allows the panel array to follow the sun's path for maximum energy collection, but opens up potential for operational and maintenance difficulties. A panel system solidly mounted to the roof is far less labor intensive, and less expensive to maintain over the life of the system. The angle of the panels on the roof will affect production, but only minimally and generally not recommenced.

On Or Above Average American Family Energy Usage

The average American family, living in a 2,000 square foot home, consumes approximately 11,000 kilowatt hours (kWh) per year. The average solar panel is rated at 250 watts. Dividing the number of kWh by the wattage of the panels gives us the number of panels needed to adequately support the household, in this case, 44.

The quality of the solar panel affects its size and efficiency, and will determine how many are necessary to provide adequate power quantity, and how much space they will take when mounted.

Equipment or appliances that require power above and beyond the household average are considered add-ons, and must be considered in the calculations. These may include swimming pools, hot tubs, air conditioning, home based workshops, or electric cars.

Lessons From Off The Grid

At certain times of the year, the sun travels far enough north to cast shadows onto my original panel array from behind, obscuring its ability to produce power. It was an eye-opening experience that led to an expanding solar panel system.

An overcast day will still provide power. A dark, cloudy day or snow covered panels will not.

Solar Power For The Not-So-Sunny Northwest


Washington receives sun exposure comparative to Maine and New York, due to their northern positions, and Washington's naturally overcast nature. With an average production rate of only 5 kWh per square meter for over half of the state, Washington solar panels can only be expected to produce 15% of the overall electricity needed to power its homes, however, local and national solar incentives may offset the cost involved to pave the way for a greener energy supply.


Oregon's solar outlook is slightly more sunny. The Energy Trust of Oregon boasts over 11,000 solar powered homes. Currently, the state requires power suppliers of a certain minimal size to provide 8% through small scale, renewable sources. Owners of Oregon solar panels that are grid tied may be eligible for cash incentives from the power company as well as a federal tax credit upon installation, offering a 100% return on investment in about 7 years, and dropping the average cost of electricity from 11.5 cents to about 9 cents per kWh in the interim.

Complex Answers To A Simple Question

Determining how many solar panels it takes to run a home is not a cut and dried answer in a tidy package, but with research and advance planning, the system you design will offer financial, energy, and environmental savings for the duration of your home's existence. To find out if solar is right for you, get started by requesting a free phone consultation with a local energy consultant.