Most morning talk shows have daily segments on what is trending — meaning what is popular currently. A better word for these rapid changes in taste would be fad — for market research, a trend is established over time and will encourage a change in behavior.
1) Trends are established via the use of statistical tests to establish a change in behavior — a lot of evidence that establishes a pattern over time.
2) A trend is established using consistent methodology
3) The analyst must be able to draw a statistical line using unbiased data gathered through consistent methodology (history is important)
4) Rigorous statistical tests must be used
5) Most important, a change in behavior must become apparent through statistical means not anecdotal evidence — for market research, circumstantial evidence is not enough!
Utility scale (multi-megawatt) solar: An established trend
Residential Solar Leases: Trending, not yet a trend
Community (group buy) Solar: Beginning to trend
Power Purchase Agreements for solar: An established trend
Tender bidding for Solar: Trending, not yet a trend
Crowd funding for solar installations: Not even trending yet
Crowd funding for solar manufacturing: Not even trending yet (would also be very dangerous)