OVERVIEW

Electric Vehicle Charging Stations (EVCS) are broken into three categories:

• Level 1 chargers are generally installed at private residences and operate on a 120V AC at 12 Amps and require 8-12

  hours to fully charge and electric battery.

• Level 2 chargers, the most common, operate on a 240V AC plug and require 4-6 hours to fully charge an

  electric battery. They typically operate from 15 to 40 Amps. Chargers are compatible with all electric and hybrid vehicles.

• Level 3 charging stations, known as DC Fast Chargers, operate on a 480V direct current plug at around 50 Amps max current and can provide an 80% charge in as little as 30 minutes. Studies indicate this fast charging can reduce the lifespan of the car's battery. 

 

It is anticipated that at the Palm and Nipomo parking structure Level 2 chargers will be installed with each charging station serving two stalls.

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EV charging spaces need to be larger than a normal parking space for PG&E maintenance vehicles to be able to access the stations in case of any problem and for customers to be able to access the charging stations. SLO electrical infrastructure falls under the National Electrical Code (NEC), the California Electrical Code (CEC), and the California Building Code (CBC) requirements. 

A charging station parking space takes up 12% more space than a standard parking spot. Below lists the amount of parking spaces the structure will have based on how many are chosen to be made to EV space codes.

• 10% EV - 410 available spaces, 41 EV spaces

• 35% EV - 399 available spaces, 143 EV spaces

• 100% EV - 368 available spaces, 368 EV spaces

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Electric Vehicle Charging System – Baseline 35%:

• City of San Luis Obispo requirements - SLO laws require that in any parking garage, if there are over 25 stalls we will need to provide 35% of the spaces to be EV charging capable spaces.

• The load is too large to a UCD (underground vault transformer); a pad mounted unit will be required,

  located within the property lines. 106” x 96” pad with 3 feet clearance all around, adjacent to a location where a PG&E truck has access.

• For a 277/480V system all the 208V power for the EV is stepped down with multiple large transformers,

  so a physically larger Electrical room would be required, with mechanical ventilation/cooling

 

Electric Vehicle Charging System – Alternate of 100% EV:

• A single service in the required capacity is not available at 120/208V.

• There would also be (6) 500kW transformers required, with associated distribution switchgear for 814

  poles of circuit breakers. This was determined by the lead engineer on the project and is due to the extremely large amount of power required to run all 368 EV charging stations.

 

PV System – partial roof coverage, 35% EV:

• The partial roof coverage system proposed is 17,000 square feet (1,600 square meters). At 15W/sf (200 W/m^2), this is an estimated peak output of 257 kW.

• At 277/480V, this is 310 Amps. 

• At 120/208V, this is 713 Amps. 

 

PV System – full roof coverage, 35% EV:

• A full roof coverage system would be 32,600sf (3,030 m^2) . At 15W/sf (200W/m^2), this is an estimated peak output of 488.85 kW.

• At 277/480V, this is 588 Amps.

• At 120/208V, this is 1358 Amps.

• NOTE: Due to San Luis Obispo building codes, if we were to decide on the full roof coverage we would have to designate the panels as the new "roof". There is a maximum height limit of 55 ft. in town, so with the panels as the roof, we would have to take out an entire floor of parking. This is most likely not an option.

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Solar Energy In San Luis Obispo

This section discusses the total daily incident solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the sun above the horizon line, and absorption by clouds and other atmospheric particles.

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The average daily incident solar energy experiences very large seasonal variation over the course of the year.

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The brighter period of the year lasts for 3.7 months, from May 1 to August 24, with an average daily incident solar energy per square meter above 7.4 kWh. The brightest day of the year is June 21, with an average of 8.6 kWh.

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The darker period of the year lasts for 3.3 months, from November 6 to February 15, with an average daily incident shortwave energy per square meter below 3.8 kWh. The darkest day of the year is December 24, with an average of 2.7 kWh.