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SMUD Customers Pay a Premium to be PV Pioneers

Sacramento residents are signing up in droves to pay a 15% premium (about $3-$7 per month) on their electric bill, in exchange for the pleasure of hosting tiny utility power plants on their roofs. The Sacramento Municipal Utility District (SMUD) is putting 4 kW grid-connected photovoltaic (PV) arrays on 100 houses per year under its PV Pioneers program, part of the utility's drive toward a goal of obtaining 54% of its electricity from renewable resources by the year 2000. SMUD installed the first 109 "mini-photovoltaic power plants" at the end of 1993, and they are generating about 400 kW. Another 134 are slated for 1994's batch (to be completed in early 1995).

A 1993 SMUD survey showed that 26% of Sacramento residents were willing to pay a premium price (15%) for electricity generated by PVs, and an impressive 70% favored the idea of using "green pricing" to support the addition of renewables to the utility's energy mix. More than 700 Sacramento area residents have signed up to volunteer their rooftops for the program so far.

Other utilities are also planning or considering implementing similar programs, including the municipal utility of the City of Austin, Texas, and Southern California Edison. And across the Atlantic Ocean, the Federal Ministry for Research and Technology in Germany is working with state governments to implement a program that will put 2,250 1-5 kW PV installations on rooftops nationwide. A surprising result of that program has been the way that participants have lowered consumption after becoming aware of their household energy use.

To be a PV Pioneer for SMUD, the volunteer's roof must be composition shingle, sloped with south to southwest exposures, and it must offer approximately 400 ft2 of shade-free space. The 4 kW grid-connected solar arrays using Siemens M55 solar panels are equipped with an inverter that converts the direct current (DC) generated by the solar array into an alternating current that feeds into the electrical grids. Each of the arrays generate enough electricity during the year to meet the average electrical needs of a Sacramento home.

Thanks to advances in technology, SMUD's costs to install solar power have come down 14% in just the last year, at $7.38 per watt for residential PV installations. The rooftop installations run about $28,000 per unit. SMUD solar program manager Don Osborn cites efficiency improvements in both manufacturing and installation for the drop in costs. "What we've demonstrated here is that you can go ahead and put in a bare bones, low-cost system that is more than adequate," says Osborn, "and achieve substantial savings by not over-designing the system unnecessarily."

Although they have not yet analyzed the data in detail, Osborn said, "The main thing the numbers are showing is that the actual performance is ... within 10%, plus or minus, of the predicted performance." The utility will install about 100 residential rooftop installations every year through 1998, at which time, Osborn said, it will probably look for a multi-year solicitation to supply either systems or energy from PVs.

SMUD also operates the world's largest utility-owned PV installation, a 2-megawatt photovoltaic plant located on a 20-acre field near the Rancho Seco nuclear plant site. The ratepayers voted to close down the nuclear plant in 1989, in favor of "cleaner" technologies such as PVs. The "PV plant" produces enough energy to serve 660 homes. SMUD also offers rebates and financing for solar water heaters, which have replaced more than 15,000 electric water heating systems in Sacramento (see "SMUD's Solar Water Heating Program," HE May/June '93 p.7).

--Abba Anderson