Photovoltaic Systems – Residential Scale Part 1 March 17, 2014

Learning Outcomes An understanding of the design process for residential scale PV projects A review of the permitting process and financing options for residential PV Case Study - A comparison of predicted and measured performance for residential PV 2

Value to participants A review of the design of a photovoltaic system leads to an understanding of the competing issues involved in solar power development and expansion An opportunity to examine residential PV systems in Arizona 3

Residential Scale PV Systems Stand Alone PV Systems  The objective is to produce electrical power for the dwelling and for battery storage Battery-Backup Grid-Connected PV Systems  The objective is to produce uninterrupted electrical power for the dwelling Grid-Connected Utility-Interactive PV Systems  The objective is to produce a specific percentage of the electrical use of the dwelling 4

Grid-Connected Utility-Interactive PV System Design Goals in any Residential Scale System o Meeting expected (or modeled) performance  Engineering professionalism o Reliable performance  Standards and Codes o Safe operation  Standards and Codes o Architectural aesthetics  Building and Zoning 5

Grid-Connected Utility-Interactive PV System Design Considerations for Residential Scale System o Design based on annual system performance  The objective is to produce a specific percentage of the electrical use of the dwelling  One needs to know:  Annual solar resource amount  Annual electricity consumption  Utility regulations on residential generation percentage o Design based on available space  The objective is to produce as much solar electricity as possible  The available space may refer to roof space or unshaded area for a ground mounted system  One needs to know:  Annual solar resource amount  Utility regulations on residential generation percentage 6

Design Steps in any Residential Scale System 1. Examination of site and estimation of performance 2. Securing financing 3. Carrying out PV system engineering and design 4. Securing relevant permits 5. Construction 6. Inspection 7. Connection to the grid 8. Performance monitoring 7 Grid-Connected Utility-Interactive PV System

Grid-Connected Utility-Interactive PV Systems Step 1 - Examination of site and estimation of performance o Inspection of roof and yards o Evaluation of obstacles, shading, and structures o Examining the solar resource 8

Step 1 - Examination of site and estimation of performance Inspection of roof and yards 9 South facing roof

Step 1 - Examination of site and estimation of performance Four common roof types 10

Step 1 - Examination of site and estimation of performance Hip roof wind zones 11

Step 1 - Examination of site and estimation of performance Layout for low wind region 12

Step 1 - Examination of site and estimation of performance Inspection of roof and yards 13 South facing roof and garage

Step 1 - Examination of site and estimation of performance Inspection of roof and yards 14 Backyard and garage west-facing roof

Step 1 - Examination of site and estimation of performance South vs West 15

Step 1 - Examination of site and estimation of performance ASU Parking Structure 16

Step 1 - Examination of site and estimation of performance “Power Pergola” 17

Motion of Sun Diagram – Phoenix 18 North Pole Summer Solstice Equinox Winter Solstice 23.5 o zenith latitude Phoenix Latitude = 33.5 o N S

Step 1 - Examination of site and estimation of performance Estimation of performance 19 PVWatts calculation – effect of module tilt

Grid-Connected Utility-Interactive PV Systems Step 2 – Securing financing o Cash purchase Customer pays cash (personal funds or loan from financial institution), system provider installs system, ownership is transferred with payment, user responsible for O&M o Dealer credit Customer pays system provider (down-payment plus installments) on credit offered by system provider, system provider installs system, ownership transferred with contract conclusion, user responsible for O&M with system provider support 20

Grid-Connected Utility-Interactive PV Systems Step 2 – Securing financing, cont. o Third Party Financing Power Purchase Agreement (PPA): System provider installs system, sells the power to the customer at a fixed rate (lower than utility rate, receives all tax credits and incentives, and is responsible for O&M with system provider support. At end of contract (10 to 25 years), customer may extend the PPA, buy the system, or have the system removed. Not allowed (or offered) in all states. Solar Lease: Similar to a PPA, but it does not involve the sale of electricity. Customer leases the system from system provider (like an automobile lease). Leases not always transferable during home sale. 21

Grid-Connected Utility-Interactive PV Systems Step 2 – Securing financing, cont. o Third Party Financing in Arizona In general, when a third party installs a PV system, it can enter a Power Purchase Agreement or a solar equipment lease arrangement with the customer. PPAs are a third party ownership arrangement, and an equipment lease is not. In Arizona, PPAs are not allowed, because that makes the third party a virtual utility - so only solar equipment leases are permitted. But there is one exception – PPAs (called Solar Service Agreements in AZ) can be established with not-for-profit governmental entities, such as schools and the like – and that is due to a case in which the Arizona Corporation Commission ruled that SolarCity would not be a utility under those circumstances. SolarCity hopes that the ACC will eventually change its mind and allow SSAs to be granted with for-profit and residential customers too. 22