Germany has spent $200 billion over the past two decades to promote cleaner sources of electricity. That enormous investment is now having an unexpected impact - consumers are now actually paid to use power on occasion, as was the case over the weekend. Power prices plunged below zero for much of Sunday and the early hours of Christmas Day on ... a large European power trading exchange, the result of low demand, unseasonably warm weather and strong breezes that provided an abundance of wind power on the grid. Such negative prices" are not the norm in Germany, but they are far from rare, thanks to the country's effort to encourage investment in greener forms of power generation. Prices for electricity in Germany have dipped below zero ... more than 100 times this year alone. Several countries in Europe have experienced negative power prices, including Belgium, Britain, France, the Netherlands and Switzerland. But Germany's forays into negative pricing are the most frequent. At times, Germany is able to export its surplus electricity to its neighbors, helping to balance the market. Still, its experiences of negative prices are often longer, and deeper, than they are in other countries. In one recent example, power prices spent 31 hours below zero during the last weekend of October. At one point, they dipped as low as minus 83, or minus $98, per megawatt-hour, a wholesale measure. Anyone who was able to hook up for a large blast of electricity at that time was paid 83 per unit for the trouble.