An Example of Residential Solar Retrofit Shawn Fitzpatrick, P.E. Energy Engineer Advanced Energy September 30, 2014

House Before Solar Retrofit

House Description Before Retrofit 900 sq.ft. conditioned space, 2 bedroom, 1 bath Built in 1949 No floor or wall insulation and poor R11 ceiling insulation Single pane windows Gas heat, Electric AC Electric tank type water heater Electric cloths dryer

House After Solar Addition and Renovation

How Bad will PV Shading Be?

The Solar Pathfinder Hemispherical reflection on dome is traced on sun chart with grease pencil Similar new devices are electronic with digital camera

Solar Pathfinder Shadow Trace One trace gives information for every month and hour in the year Add up unshaded percentages for each month This gives the percentage of solar availability for each month

Solmetric SunEye - Digital Shade Analyzer

Calculation of Shade Factor from Pathfinder Month Sun Chart % Solar Availability Avg. Sunhours/Day (kWh/m2-day) Available Sun Hours (kWh/m2-day) Jan56.0% Feb61.0% Mar68.0% Apr73.0% May97.0% Jun95.5% Jul97.0% Aug78.5% Sep70.5% Oct63.0% Nov57.0% Dec51.0% Average Shade Factor0.74

How Is the PV Doing? PV modules are now 21 years old. They were originally installed on a Duke Energy project in Charlotte, NC in I installed my second-hand PV in February 2006 (~ 8 yrs. ago) The average annual solar production for recent 6 years was 2067 kWh/yr. Based on PV Watts software, PV was expected to produce 2290 kWh of electricity per year PV production over last 6 years is within 10% of expected

PV Generation and House Usage

How Is the PV Doing? PV generation has remained almost constant over 6 years (varied with weather) House consumption has increased somewhat during this time but leveled out the last few years 2007 PV generation equaled 87% of house consumption 2012 PV generation equaled 56% of house consumption

2012 Monthly Solar Generation and House Usage

Shawn Fitzpatrick, P.E. Energy Engineer Advanced Energy