1. raivarun@gmail.com Solar PV Adoption in the U.S. Residential Sector: Decision-Making & Behavior Change Varun Rai Assistant Prof of Public Affairs and Mechanical Engineering University of Texas at Austin varun.rai@mail.utexas.edu BECC Conference 2011, Washington D.C. 1 December 2011

2. The Project Decision-Making and Behavior Change in PV Adopters Influence of contextual and attitudinal factors – Impact of electricity rates, incentives, and socio-demographics (income, home value, environmental beliefs, etc.) Uncertainties and non-monetary costs, and information networks – Individual discount rates – Information networks Post-installation experience – Awareness of electricity use – Behavior change Rebound or Ripple Load-shifting 2

3. 3 Data Survey of PV owners –Completed in Texas during Aug-Sep 2011 365 completed responses (2004-2011) ~20% of the target population Data collected on –System details –Decision-making process –Financial aspects –Sources of information –Post-installation experience (Some of this is reported below) –Environmental attitude –Demographics

4. Awareness Change Enhanced Across-the-board 4 “I am much, much, much, much, more aware of how much energy I use each month.”

5. 5 Rebound or Ripple? Ripple effect/Double dividend –Do adopters become more aware and conscious of their energy use and the environment, thereby motivating them to further reduce their consumption? Rebound effect –Do adopters increase electricity consumption after installing PV, because of adopters’ perception that solar energy is clean and essentially free?

6. 6 Reported Behavior Change: Energy Conservation Change in awareness is the most significant driver of reported behavior change The odds for increased consumption are significantly higher (~2.5 times) for very high-income group (>$250k/yr) compared to the $85-120k/yr group Ongoing parallel analysis: Analyzing pre-/post- electricity bills “I try to "leverage" the array's input in relation to total electrical consumption so my array will provide 25% of all our power needs.”

7. 7 Load-Shifting to Peak Hours Change in awareness is the most significant driver of load-shifting behavior Need alternative electricity rate structures (e.g., time-of-use) to get the peak generation from solar onto the grid. Otherwise load-shifting will mitigate the peak value of PV “I am more apt to use power-consuming appliances (washer/drier, etc) when the sun is up, to take advantage of the cost offset.”

8. 8 Summary of (Initial) Findings Most PV owners report a substantial increase in awareness of their electricity bill and usage Strong evidence of “perceived” ripple effect/double dividend –Nearly 45% report reduction in total electricity consumption, and attribute it to their increased awareness –Evidence of spillovers and “self competition” to save Small “reported” rebound effect (%5 respondents) –Rebound effect significantly correlated with very high income Over 30% report load-shifting to better match their consumption with electricity form their PV system

9. Awareness Change Some Open-ended Responses 9 –“[Our awareness has changed] a lot, [solar PV is a] great education tool on home electricity usage.” –“We became aware of how we were using electricity and ways to conserve. We implemented those conservation methods at the same time we installed the PV system.” –“All appliances and lights have been converted to high efficiency and we're much more likely to turn off unused equipment. The primary reason is the feedback device in my home that tells me how much electricity we're using and the online graphing of same.” –“Concurrent w/ installation I installed whole-house energy monitoring, which has made me much more conscious of power usage on a daily basis.” –“With the monitoring system we have I can tell when we run a hair dryer or our microwave.”

10. Behavior Change: Energy Conservation Some Open-ended Responses 10 –“I have become more of an energy conserver.” –“I try to "leverage" the array's input in relation to total electrical consumption so my array will provide 25% of all our power needs. Turning lights off, hand washing dishes, cold water washing, opening windows and turning up the AC when possible.” –“Self competition” to save –“More conscious of the usage and we installed a new roof/insulation/radiant barrier at the same time as the PV system.” –Spillovers/Ripple –“Now that much of the electricity is free, I tend to not worry as much about cutting back on electric usage.” –“Feel more relaxed about using electricity esp during the day.”