Events like the current heat wave in California, which is stressing the state’s electricity system and pushing energy prices up, are leading a growing number of businesses and homeowners to look into solar panels and other alternative energy technologies. Kyocera Solar Inc. has signed deals with three San Diego companies to install large-scale solar systems. New housing tracts in Carlsbad and El Cajon are offering to equip homes with solar-powered water heaters for an additional $2,600. Solar power systems have recently been installed at three San Diego schools. Even before this summer’s energy crunch, Californians were increasingly turning to green power. Last year, 12.2 percent of the state’s net electricity was generated by alternative means — geothermal, biomass, solar, wind, and small hydroelectric systems — up from 10.2 percent in 1997.