Why Performance Metrics? by Mouli V, PhD PE CEM NABCEP PV President, SolarPod TM Solar Minnesota meeting Convened by: Rebecca Lundberg, MRES & MnSEIA Board

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.

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.

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.

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: – kW – Promised per RFP: 57,107 kWh/yr = 1438 kWh/kW/year Public Installation 3: – kW – Promised per RFP: 144,965 kWh/yr = 1438 kWh/kW/year Public Installation 4: – kW – Promised per Brochure: 19,500 kWh/yr – 1290 kWh/kW/year = Actual 2/3 Public Installation 5: – kW – Promised per Ad: 28,000 kWh/year – 1440 kWh/kW/year = Actual 1/2

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 , 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

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

Proposal – Fixed Tilt Latitude 44 o 30’ through 45 o 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. Red is failing grade 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.

Proposal – Tracking Latitude 44 o 30’ through 45 o 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. Red is failing grade 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.

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.