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Quick Facts: Residential Photovoltaic

Updated November 16, 2016
  1. A home solar system is typically made up of solar panels, an inverter, wiring (meter and disconnect switch) and support structure.
  2. A typical rooftop solar electric system is connected to the utility grid and relies upon the grid infrastructure for backup power. It will not operate in the absence of utility power.
  3. A modest PV system will pay for itself during the life of the equipment, generally several times over.
  4. Solar increases the value of your home.
  5. Solar equipment helps protect you from rate increases and fuel cost uncertainties.
  6. Use of solar helps decrease air pollution problems related to burning fossil fuels.
  7. Solar Energy is measured in kilowatt-hours. 1 kilowatt = 1000 watts. 
  8. To figure the cost of a photovoltaic system the system size is multiplied by the installed cost per watt.  A 1 kW system that costs $4 per installed watt would cost $4,000 (1,000 x $4 = $4,000).
  9. Larger systems have a lower cost per watt.
  10. Solar energy systems qualify for state and federal tax credits and exemption from Arizona sales tax.  The effective cost of a solar system can be reduced by utilizing an Arizona state tax credit (25 percent up to $1000) and a federal tax credit (30 percent). These credits can be used to reduce tax payments, but are not refundable. The Arizona tax credit is claimed using Forms 310 & 301.  Available at Arizona credit tax forms. The $1,000 is a cumulative limit per taxpayer.
  11. A one kilowatt solar system that cost $4,000 to install would be reduced by a $1000 state tax credit and $1200 federal tax credit.  The out-of-pocket cost would be $2800.
  12.  A photovoltaic energy system generates units of energy measured in kilowatt-hours.  One kilowatt-hour (kWh) is the amount of electricity needed to burn a 100 watt light bulb for 10 hours.
  13.  A 1 kilowatt home solar system will generate approximately 1,500 - 1,680 kilowatt-hours per year in Arizona (varies with location, orientation, any shading, and other factors).  The average Arizona utility electric rate is $0.12 a kilowatt-hour – meaning the energy offset by a 1 kilowatt solar system is equal to $201.60 (1680 x $0.12 = $201.60).
  14. If a 1 kW photovoltaic system cost $2800 to install (after incentives), and saves $201.60 a year in electricity costs – the simple payback period would be 14 years. This does not include the savings made by not paying higher future utility rates on the saved energy.
  15. There may be some utility fees that reduce these savings
  16. A typical Arizona home generally has an electric utility service rated at 200 amperes.  This generally limits the size of the inverter to about 8,000 watts without extra costs.  An inverter rated at 8,000 watts can generally use a photovoltaic array rated at up to 10,000 watts (10 kilowatts).
  17. If the photovoltaic array is in an area with shadows, or must face other than South, the performance will be affected.
  18. In one hour more sunlight falls on the earth than what is used by the entire population in one year.
  19. Remember- Use of solar helps decrease air pollution problems related to burning fossil fuels.

Quick Facts: Solar Hot Water

Updated: January 20, 2014
  1. Solar water heaters pay for themselves in 3-10 years, depending on your hot water use and whether you are comparing to gas or electric water heating.
  2. A simple passive system only adds about $15/month to your mortgage and pays for itself long before your mortgage is paid off.
  3. The total costs (initial cost, fuel, maintenance) over the life-ycle of a solar water heater is one of the lowest of all water heating systems available.
  4. Solar increases the value of your home and provides an appealing sales feature.
  5. Your solar equipment has value independent of your house. You could sell your solar equipment or take it with you when you move.
  6. Take advantage of state and federal income tax credits (25% up to $1000 state; 30% federal) and exemption from state sales tax.
  7. Utility companies offer rebates for the purchase of solar equipment including solar water heaters. Check with your utility to see if any rebate applies in your area.
  8. Increased use of solar will help decreases environmental problems caused by burning fossil fuels.
  9. Use of solar energy creates quality local jobs by expanding the local solar industry.
  10. Use of solar provides you with more independence in your personal life.

A Field of Mirrors

When the Abengoa Solana CSP plant went online in October of 2013, it was the largest working parabolic trough plant in the world (since surpassed). Solana covers more than 1,900 acres in central Arizona and it created over 2,000 construction jobs and 85 permanent jobs. These numbers do not take into effect the number of indirect jobs created as a result of the injection of capital into the community and state.

Arizona Public Service, the state’s largest electric utility, has contracted to purchase all the power generated by Solana for 30 years. On a daily basis, APS determines how Solana should produce and store its energy in order to best meet local demand. The 3,200 concave mirrors concentrate light onto the heat transfer fluid, heating it to 740 degrees Fahrenheit. About 270 miles of pipe transport the fluid to the power block where it can either be sent to the steam generator to boil water and create steam to drive two 140 megawatt turbines, or it can be sent to one of 12 giant salt tanks to be stored for later use. The salt tanks can hold the heat from the fluid for up to six hours. When electricity is needed, the heat in the hot salt is transferred into another holding tank where it is converted into steam to produce electricity.

One major drawback of CSP plants like Solana is that they need significant water for their cooling operations; however, the project’s land was previously designated for agriculture and the plant uses 75% less water for solar energy production than its previous designation.

Abengoa estimates that under optimal conditions, Solana can produce enough electricity to power 70,000 homes.