Why Performance Metrics? by Mouli V, PhD PE CEM NABCEP PV President, SolarPod TM

1. Why Performance Metrics?byMouli V, PhD PE CEM NABCEP PVPresident, SolarPodTM Solar Minnesota meeting Convened by: Rebecca Lundberg, MRES & MnSEIA Board

2. Why Performance Metrics • Customers must be informed about how a system is performing. • Equipment supplier and installer must be aware of what they are promising. • Over estimation and under performance are both detrimental to the overall solar PV industry.

3. Why Performance Metrics • RFPs have been written where expectations were way above reality. • Many of us have lost out due to unrealistic energy projections by NREL, RFP owners and installers.

4. Important points • Some of you may recognize the next slide’s systems and installations • The purpose is only to bring out the reality in Minnesota. • I would have got the same results if I had used the same.

5. Some examples of estimation • Public Installation 1: • 600 kWh system • Promised per RFP: 750,000 kWh/yr = 1250 kWh/kW/year. • Actual is 1200 kWh/kW • Public Installation 2: • 39.715kW • Promised per RFP: 57,107 kWh/yr = 1438 kWh/kW/year • Public Installation 3: • 100.815 kW • Promised per RFP: 144,965 kWh/yr = 1438 kWh/kW/year • Public Installation 4: • 15.12 kW • Promised per Brochure: 19,500 kWh/yr • 1290 kWh/kW/year = Actual 2/3 • Public Installation 5: • 19.44 kW • Promised per Ad: 28,000 kWh/year • 1440 kWh/kW/year = Actual 1/2

6. MN state study (2002 to 2008) After the first phase of the program was initially introduced in 2002, there were few solar rebate applicants. It was not until 2006 that the $1.15 million available was fully reserved. For the most recent biennium, fiscal years 2008-09, the additional $1.2 million appropriated was fully reserved eight months prior to the end of the funding cycle. Acknowledgement: Ms. Stacy Miller, Office of Energy Security. Link to study

7. PV Watts - NREL • Most used s/w model. • Mostly over estimates production. • 0.77 de-rate factor table.

8. Proposal – Fixed TiltLatitude 44o 30’ through 45o 10’ Residential • A color coded system. • Yellow : >1201 kWh/kW • Green: 1101 to 1200kWh/kW • Blue : 1000 to 1100 kWh/kW • Red : Below 1000 kWh/kW YGB are accepted ranges. Red is below accepted range. Commercial / utility / Industrial • A color coded system. • Yellow : >1201 kWh/kW • Green: 1101 to 1200kWh/kW • Red : Below 1100 kWh/kW YG are accepted ranges. Red is below accepted range. Red is failing grade

9. Proposal – TrackingLatitude 44o 30’ through 45o 10’ Residential • A color coded system. • Yellow : >1501 kWh/kW • Green: 1301 to 1500kWh/kW • Blue : 1200 to 1300 kWh/kW • Red : Below 1200 kWh/kW YGB are accepted ranges. Red is below accepted range. Commercial / utility / Industrial • A color coded system. • Yellow : >1501 kWh/kW • Green: 1301 to 1500kWh/kW • Red : Below 1300 kWh/kW YG are accepted ranges. Red is below accepted range. Red is failing grade

10. Summary • All of us have been affected by unrealistic performance expectations and delivery. • Unrealistic estimation effects the overall MN solar PV industry. • This hopefully will convince all of us to use metrics that are realistic so that the playing field is fair and level.