Solar Energy 101

Yes! Even Portland and the rainy Willamette Valley receive as much sunshine annually as the average U.S. city. In fact, solar is Oregon’s most abundant renewable resource. Today, more than 17,000 Oregon households use solar energy systems to generate electricity or heat water.

Half of the electricity we use in Oregon is generated by power plants that burn fossil fuels. The emissions from these plants contribute to climate change and pollution. The sun is a clean, renewable source of energy that can help us reduce our dependence on fossil fuels.

Solar works best on south-facing roofs, though east or west-oriented roofs may be suitable as well. There should be little or no shading from trees, buildings, chimneys or roof gables on or adjacent to your home. Remember, locations with no shading in the winter may be shaded by spring and summer foliage.

The two most common solar energy systems that you can add to your home are solar water heating and solar electric. A solar water heating system preheats the water that goes into your existing water heater, which reduces the amount of gas or electricity your water heater consumes.

A solar electric system generates electricity that can be used throughout your home, which reduces the amount of electricity you need to purchase from your power company. When your system generates more electricity than you use, the excess goes into the grid and you receive a credit from your utility.

System prices vary. A typical solar water heating system costs $6,000–$9,000.

For a solar electric system, the cost depends on the size of the system and the ease of installation, with an average cost range of $8,000–$11,000 for each kilowatt (kW) of capacity. However, incentives and tax credits can cover up to half the cost for both types of systems. Read more about costs, tax credits and incentives.

A solar system reduces your energy costs and may add value to your home. The added value is up to 20 times your annual energy cost savings, according to The Appraisal Journal.

At today’s electricity and gas prices, a solar water heating system and a 2-kilowatt solar electric system could each save the average family of four $150 or more a year. Based on these savings, each system could add up to $3,000 to the value of a home.

A solar water heating system is one of the most affordable ways to go solar and can offset one of the biggest energy users in your home. Residential solar water heating systems typically save 1,500–3,000 kilowatt-hours (kWh) of electricity or 80–150 therms of gas per year. That’s 60% of the energy used to heat water in an average Oregon home. In the summer, your system may meet 100% of your hot water needs.

In addition, cash incentives are available from Energy Trust of Oregon for eligible Oregonians. Water heating incentives are available to Oregon customers who heat their water with electricity from Portland General Electric (PGE) or Pacific Power or gas from NW Natural or Cascade Natural Gas. Solar electric incentives are available to Oregon customers of PGE and Pacific Power.

With a solar electric system, energy production is directly proportional to system size. In Portland, a 1-kilowatt solar electric system, optimally oriented with minimal shade, will produce approximately 1,000 kWh per year. A 3-kilowatt residential system will supply about 3,000 kWh annually, or 25% of an average Oregon home’s annual electricity needs (an average four-person household uses 12,000 kWh/year). Improving your home’s energy efficiency will reduce your energy use so your solar system will meet a higher percentage of your needs.

Both solar electric and solar water heating systems utilize panels that are most commonly mounted on your roof. Solar water heating panels, called collectors, are usually 30-50 square feet in size. A typical system has one or two collectors. Photovoltaic panels require about 100 square feet of area for each kW installed.

A solar water heating system typically includes an 80-gallon solar storage tank that is installed near your existing electric or gas water heater. Both conventional tank and tankless units are compatible with solar water heaters. If you don’t have room for a second tank, units that contain the solar storage and an electric water heater in a single 120-gallon tank are available.

A solar electric system includes a wall-mounted inverter to change the DC electricity produced by the panels into AC “household” electricity. The inverter is a little bigger than a briefcase and can be installed indoors near your breaker panel or outdoors in a shaded location.

Yes. However, to qualify for an Energy Trust incentive, a system must be installed by an eligible contractor. To be eligible for a state energy tax credit, a system must pass an Oregon Department of Energy inspection.