UrbanRE Vitalization Group LLC

Bringing Milwaukee a prosperous future through clean, renewable, reliable and economically sustainable solar energy.

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Solar Electricity Basics

The most common types of solar-electric systems are grid-tied or off-grid (stand-alone). In an urban environment the most common type of application is grid-tied with the utility company.


Grid Tied Solar-Electric Systems

Also known as on-grid, grid-tied, solar-electric systems generate solar electricity and send it to back
out to the electric utility grid, offsetting a home’s or business’ electrical consumption and, in some instances, becoming a net-zero building or producing more than a building needs.  In Wisconsin, various utilities credit a homeowner’s account for excess solar electricity produced. This is called net metering or net billing. The specific terms of net metering laws and regula
tions vary from state to state and utility to utility. Contact your local electricity provider or state regulatory agency for their guidelines.

 

 Primary components of grid tied solar electric system.

 

 

 

System Components

Solar-Electric Panels
solar-electric modules, photovoltaic (PV) panels

PV panels are a solar-electric system’s first and main component, where sunlight is used to make direct current (DC) electricity. Wafers of a semiconductor material use the light (photons) from the sun to generate electricity—what’s known as the photovoltaic effect. Other components in your system enable the electricity from your PV panels to safely power your electric needs by turning DC electricity into AC (alternating current) and be used by the home or business.  Multiple modules combined together are called a PV Array. Although panels are the most common form of solar electricity collector, PV technology also has been integrated into glass, building facades, roofing shingles or tiles, and laminates for metal standing-seam roofs. Most PV Modules carry 25-year warranties. They can withstand severe weather, including extreme heat, cold, and hail.


Array DC Disconnect
PV disconnect

The DC disconnect is used to safely interrupt the flow of electricity from the PV array. It´s an essential component when system maintenance or troubleshooting is required. The disconnect enclosure houses an electrical switch rated for use in DC circuits. It also may integrate either circuit breakers or fuses, if needed.


System Meter

System meters or Computer based monitoring software for PV systems measure and display several different aspects of your solar-electric system’s performance including how much electricity your solar panels are producing or have produced; and how much electricity is in use so you can control your usage and costs. Operating your solar-electric system without metering is like running your car without any gauges, although possible to do, it’s always better to know how much fuel is in the tank.


Inverter

Inverters transform the DC electricity produced by PV modules into the alternating current (AC) electricity. Grid-tied inverters synchronize the electricity they produce with the grid’s utility grade AC electricity, allowing the system to feed solar electricity to the utility grid. Most grid-tied inverters can be installed outdoors.


AC Breaker Panel & Inverter AC Disconnect

The AC breaker panel is where all of a home’s electrical wiring meets with the incoming wiring, whether that’s the grid or a solar-electric system. This wall-mounted panel is usually installed in a utility room or basement. It contains a number of labeled circuit breakers that route electricity to the various rooms throughout a house. These breakers allow electricity to be disconnected for servicing, and also protect the building’s wiring against electrical fires. An inverter’s electrical output needs to be routed through an AC circuit breaker. This breaker is usually mounted inside the building’s mains panel, which enables the inverter to be disconnected from either the grid or from electrical loads if servicing is necessary, and also safeguards the circuit’s electrical wiring.


Kilowatt-Hour Meter

Homes with a grid-tied PV system will have AC electricity both coming from and going to the electric utility grid. A bidirectional KWH meter keeps track of how much electricity flows in each of the two directions and provides the information you need to monitor how much electricity you’re using and how much your solar-electric system is producing.