The use of solar power has be used for almost 200 years. In the 17th and 18th centuries people used to coat water storage tanks with solar absorbers so they can heat the water for showers.
The last time solar energy was in prominence was during the 70's during the last oil shock. At that time there were many tax incentives to install thermal solar panels used to heat water. The speaker at the conference stated that "These tax credits were one of the worst designed since people were actually able to make money on the credit by installing cheap and poor performing systems." This gave the entire solar industry a bad name during this time frame and it has taken over 20 years to overcome this tax dodge reputation.