|Genzyme Center’s Photovoltaic (PV) System
A photovoltaic system is a group of solar panels. A photovoltaic system consists of panels called modules. A complete system is called an “array” of modules.
Photovoltaic (PV) Systems produce electricity.
Photovoltaic energy produces about 1% of Genzyme Center’s electricity.
PowerLight Corporation located in San Francisco, CA, designed Genzyme Center’s photovoltaic system. (www.powerlight.com) PowerLight hired a local electrical union contractor and roofer to work with Turner Construction to install Genzyme Center’s PV System. In January 2007, SunPower Corporation of San Jose, CA acquired PowerLight Corporation.
Genzyme Center has two PV Systems that are wired together to perform as one. The system powers one inverter which converts electricity generated by the PV System (DC power) into power that we can use in the building (AC power).
The modules are made of tempered glass and are 3 ½’ x 4’ in size. They fit together in a tongue and groove format. The PV System covers 1,625 square feet of roof surface.
14th floor – roof of penthouse
56 modules with a 10.6 kilowatt rating
15th floor – roof of 14th floor mechanical room
72 modules with a rating of 13.6 kilowatt rating
The total cost of Genzyme Center’s PV System was $300,000. Genzyme received a grant of $225,000 from Massachusetts Renewable Energy Trust towards the system. Depending upon energy prices in future, it will take approximately 15-20 years to pay for itself.
Generated power from the PV System is used within the building electrical system as soon as it is delivered. The system produces power proportional to how much sunlight there is. The system is always “live” when the sun is out. On rainy or cloudy days, the system produces electricity but, less then a sunny day. PV Systems do not store energy. There is no power generated at night. There is a fluctuation in electricity produced throughout the year due to seasonal changes.
Genzyme has a 5 year warranty on our PV System. The system is virtually maintenance free. A semi-annual visual inspection is all that is needed. The modules do not need to be cleaned. MA gets enough rain to keep the modules clean. No work is allowed to be done to the PV System without SunPower’s approval.
A layer called a “slip sheet” was laid on top of the roofing material. The modules were then laid in place using the tongue and groove system. Next, T-Clear was laid on top of the modules to act as an insulator. (T-Clear looks like thick plastic wrap.) The modules were then wired together and grounded. The modules are wired together in groups of eight. Concrete pavers were put along the module edges to keep the system parameter from lifting due to excessive wind gusts.
A meteorological station is connected to the PV System and is located on the 15th floor roof. It is located close to the roof to ensure accurate readings. The “met” station monitors: wind speed, temperature and sun intensity.
The modules are connected to a terminal box in a series of eight. Photovoltaic Systems produce DC power. The terminal box converts the electricity to AC power to use in Genzyme Center. (DC in – AC out.) AC power is full utility power.
Terminal Box - DC/AC Components:
Source Circuit Combiner
DC Disconnect (breaks positive)
DC to AC inverter
AC and DC connections
Utility required Disconnect and Back Fed Panel Board (Circuit Breaker)
There is an “ON/OFF” switch for the whole system.
Lightning protection – There is a “lightning arrestor” that is connected to the source circuit combiner.
Electricity flows like water in a river. The produced electricity goes to the “load” meaning there is no specific usage for the solar produced energy. It is used throughout the building. If power in Genzyme Center shuts down completely, the PV power will turn off.
The PV System produces no negative environmental impact.