Solar power is still a marginal energy source, accounting for about 1 per cent of global electricity production. Yet, its environmental impact is already considerable, according to the Silicon Valley Toxics Coalition. The San Francisco-based group started out three decades ago tracking the e-waste produced by high-tech industry. It now produces an annual Solar Scorecard on panel manufacturers that depicts an industry that has got worse over time. Most producers refuse to provide any environmental data on their supply chains or manufacturing operations at all.