Solar prices in the US in 2013 fell by a further 15% year on year, a study from the Department of Energy and Lawrence Berkeley National Laboratory has found.

The report ‘Tracking the Sun’ is the seventh edition summarising PV prices from 1998, up to the first half of 2014, across the US.

The study concluded that between 2012 and 2013 solar prices fell by 12-15% depending on system size, averaging US$0.07 per year.

The median installed prices in 2013 were US$4.7 per watt for systems under 10kW, US$4.3 per watt for systems of 10-100kW, and US$3.9 per watt for systems over 100kW.

The report surveyed 300,000 residential, commercial and utility-scale solar systems, across 33 states, representing 80% of grid connected solar in the US and looks at the dollar cost per watt for solar.

The report was conducted by the Lawrence Berkeley National Laboratory and is part of the US Department of Energy’s SunShot Initiative to decrease solar costs by 75%, by 2020.

The major cause of system cost decreases since 2008 has been down to module price reductions; module prices fell by US$2.70 per watt 2008 to 2013, according to the report.

But even in 2012-2013, when module prices stagnated, costs continued to come down, suggesting efforts to reduce non-module costs in systems are paying off.

The US is targeting its soft-cost issue through the SunShot Initiative.

The report also found that last year cash incentives for PV installations, such as tax rebates, fell by 40-50%, aligned with the falling total installation cost. National trade association, the Solar Energy Industries Association (SEIA), added that overall, incentives had declined by a total of 85-95% since peaking a decade ago.

But compared to international markets, the study found the US has relatively high prices. Compared to the other top PV markets of Germany, Italy, Japan, France and the UK, across the globe prices for systems up to 100kW are lower than the US, except for Japan.

Germany was found to have prices more than 50% less than system costs in the US.

“In just a few years, American ingenuity and smart policy have made solar a true success story. These price declines mean that solar power is now an affordable option for families, schools, businesses and utilities alike,” said Adam Browning, executive director of US solar campaign group, Vote Solar.

“This report highlights yet another reason why solar energy has become such a remarkable American success story. Today, solar provides 143,000 good-paying jobs nationwide, pumps nearly $15 billion a year into the U.S. economy and is helping to significantly reduce pollution,” added SEIA president and CEO Rhone Resch.