A Local Solar Electric Example

This is a report on the pros and cons of the grid-tied solar power system that was installed in my home in September 2010. It is typical of eight (8) other systems already in operation in Dreamland Villa. “Grid-tied’ means that it is connected to the SRP power lines to sell back any excess electrical energy generated by my panels as well and supply power we need when the sun is not shining. This 5.16 Kilowatt system was meticulously engineered by Sun Valley Solar Solutions with offices in Chandler. The design and installation was approved and overseen by SRP engineers as well as inspected and approved by Maricopa County.

The system has twenty four (24) 31” X 61” panels mounted on racks firmly attached to the roof facing south. Power from the panels is lead through a conduit to the Inverter on the side of the building. The inverter changes the Direct Current (DC) from the panels to Alternating Current (AC) used in the home. Power is metered and eventually distributed to the home wiring circuits and/or SRP by the circuit breaker box. Sun Power Corp. (mfg. of the inverter and panels) monitors the system to insure its optimum operation.

Costs
The gross cost, $31,500, of this system, was reduced by a $10,750 SRP rebate, a $6,200 Federal Tax credit and $1,000 Arizona credit. The substantial final out-of-pocket cost (13,550) might be too costly for many folks even though eventually you gain back the cost through utility bill savings. The payback time is estimated to be 8-9 years depending on possible future SRP rate increases. Check for the latest SRP rebates and state and federal tax credits. Also remember that the federal and state tax credits are included in the initial out-of-pocket cost and are recovered as reductions in one’s income taxes, possibly over two tax years. There is some bad news, in that SRP has reduced their current contribution. Arizona’s utilities contribute to home mounted solar systems due to mandates by the Arizona Corporation Commission’s mandates to foster renewable energy. An offsetting plus is that appraisers feel that a home with solar has perhaps a higher value of approximately $20,000.

Solar water heating was first considered, but dropped due to our low hot water needs, with only occasional showers and the dishwasher needing it. Now my water is heated along with power for all the other electrical using devices in the home.

Conservation
Reducing power use is always smart, it reduces your expenditures and reduces your utility company’s use of fossil fuels and the need to purchase power during the summer peaks. Eliminating a second refrigerator, drying the laundry outdoors, turning off unnecessary appliances and lights will enhance savings even before solar is installed. These savings continue to enhance savings added by solar.

System Performance
High temperatures reduce the panel output, as well as: dusty panels, cloudy days and objects casting shadows on panels. The length of daylight varies from about 10 hours in mid-December to over 14 hours in mid-June. In mid-June the sun’s angle is 80 degrees above the horizon with the sun a 33 degrees in mid-December. The Phoenix area has over 300 sunny days a year which makes it an ideal location for solar power generation. December, January and February are the peak heating months with July, August and September requiring peak cooling. Expect October, November, March, April, May and June to generate more power than needed with the excess power carried over and credited to the following months.

Actual performance of my solar power system measured by KWH consumed before October 2010 (10) when the system was turned on. From October 2010 through February 2011, power purchased was drastically reduced. March through July 2011 more power was generated than used and carried over to the following months. A daily record of KWH produced shows that power was produced every day of the year, although on 6 or 7 days the power amount was minimal. I believe that light filtered through all day cloudiness still produces some power.