under normal circumstances lasts three and a half hours. Impact on solar power An eclipse causes a reduction of solar power generation where the Moon shadow covers any solar panel, as do clouds. The North American Electric Reliability Corporation predicted minor impacts, and attempted to measure the impact of the 2017 eclipse. In California, solar power was projected to decrease by 4–6,000 megawatts at 70 MW/minute, and then ramp up by 90 MW/minute as the shadow passes. CAISO's typical ramp rate is 29 megawatts per minute. Around 4 GW mainly in North Carolina and Georgia were expected to be 90 percent obscured. After the 2017 eclipse, grid operators in California reported having lost 3,000–3,500 megawatts of utility-scale solar power, which was made up for by hydropower and gas reliably and as expected, mimicking the usual duck curve. Energy demand management was also used to mitigate the solar drop, and NEST customers reduced their demand by 700 MW. NV Energy prepared for the solar eclipse months in advance and collaborated with 17 western states. When the eclipse began covering California with partial darkness, which reduced its usual amount of solar-generated electricity, NV Energy sent power there. Likewise, when Nevada received less sunlight, other west coast states supplied electricity to it. During the solar eclipse, the state of Nevada lost about 450 megawatts of electricity, the amount used by about a quarter million typical residences. The 2015 eclipse caused manageable solar power decreases in Europe; in Germany, solar power dropped from 14 GW to 7 GW, of a 38 GW solar power capacity. Commemorative stamp On June 20, 2017, the USPS released the first application of thermochromic ink to postage stamps in its Total Eclipse of the Sun Forever stamp to commemorate the eclipse. When pressed with a finger, body heat turns the dark image into an image of the full moon. The stamp was released prior to August 21, so uses an image from the eclipse of March 29, 2006 seen in Jalu, Libya. Videos Gallery Totality (Images where the sun is completely eclipsed by the moon) Transition (Images showing Baily's beads or a Diamond ring, which occur just as totality begins or ends) Partial (Images where the sun is partially eclipsed by the moon) Images produced by natural pinholes (Images of the eclipse created by natural pinholes formed by tree leaves) Views outside of the US Related eclipses Occurring only