Plans for the construction of 800 MW of solar photovoltaic (PV) capacity in the USA by 2013 indicates that the technology is reaching parity with other forms of renewable energy, according to Pacific Gas & Electric (PG&E).

The California-based utility has signed contracts with two solar power plant developers to buy the renewable energy from two key projects, but says that development of the new plants is dependent on the extension of the federal investment tax credit for renewable energy.

The two projects – located in San Luis Obispo County, California – will more than double the USA’s current level of grid-connected PV generating capacity and are part of the state’s plans to rapidly increase the level of renewable energy use. The choice of PV over other forms of solar and renewable energy technologies indicates that recent advances in materials are bringing down the cost of the technology.

“These landmark agreements signal the arrival of utility-scale PV solar power that may be cost-competitive with solar thermal and wind energy,” said Jack Keenan, chief operating officer and senior vice president for PG&E.

Topaz Solar Farms LLC, a subsidiary of OptiSolar Inc., says that its 550 MW PV plant will use thin-film technology and will start delivering power in 2011. The company’s agreement with PG&E is for delivery of an average of 1 100 000 MWh/year of electricity from the farm, which will be fully operational in 2013.

High Plains Ranch II, LLC, a subsidiary of SunPower Corporation is to build a 250 MW PV plant that will deliver an average of 550 000 MWh/year to PG&E. The plant will use SunPower’s proprietary crystalline PV solar cells and will start delivering energy in 2010.

When complete, the Topaz solar farm will be the largest of its kind in the world. OptiSolar says it hopes to start construction in 2010 following completion of the local approval process. Installation of the plant, which will occupy nine square miles of land, will take up to three years.

These and other solar projects in the USA rely on the country’s tax credit system, which reduces the tax liability for utilities that make investments in renewable energy projects. The current programme is due to expire at the end of the year but the US House of Representatives and US Senate are wrangling over its extension.

The American Council on Renewable Energy recently labelled the failure to extend the tax relief system for renewable energy as “outrageous and intolerable” and a threat to the $17 billion US renewable energy industry.

California’s Renewable Portfolio Standard requires that utilities secure at least 20 per cent of their electricity from renewable energy sources by 2010. The state has also set a goal of increasing renewables to 33 per cent by 2020.