Solar panel producers are intensifying efforts to replace silver with alternatives such as copper after silver rallied 130% over the past year, squeezing margins already under pressure from production overcapacity, particularly in China, industry experts said. "Silver is the greatest contributor to the increased cost of manufacturing solar panels," said Derek Schnee, senior commercial solar consultant at JK Renewables, adding that the cost of solar panels has increased 7-15% over the last 12 months.