Solar & Wind
This diagram and information will provide a basic understanding of the main components of a photovoltaic solar system and how it works.
PV panels are the main component of a solar-electric system and determine its output capacity. Photons of light strike the semiconductor cells of a solar panel exciting electrons which then flow as a stream of direct (DC) current.
PV panels are rated in watts based on the maximum power they can produce under ideal sun and temperature conditions. The more directly the sun strikes the panels and the lower the air temperature around the panels’ results in the highest production. The individual panel rated output is used to determine how many panels would be needed to meet the requirements of a specific electrical demand. Multiple panels are usually wired together to achieve a desired quality of electrical output and are called strings. All the strings together are called an array.
Rigid panels are the most common form of solar electricity generation because to date they have by far the highest level of efficiency. PV modules are very durable and long lasting with all panels sold by Edison Solar & Wind carrying a 25-year manufactures warrantee. They can withstand severe weather, including extreme heat, cold, and the contact of limited size hail stones.
Mounting Racks (not pictured)
Mounting racks are used to affix solar panels to a secure structure so that they stay in place and maintain their desired orientation to the sun. Panels can be mounted in three ways: 1) on a rooftop, 2) in a rack on top of a steel pole set in concrete, or 3) horizontally on a ground level bank mounting system. Rooftop mounting is most common because it is above many flying objects, requires no additional space, and is usually cheaper in that it does not require the construction of a support structure. In areas with a lot of space, pole or ground-mounted arrays are often chosen.
Mounting racks may incorporate other features, such as adjustability. The sun is higher in the sky during the summer and lower in the winter and moves across the sky from east to west each day. Adjustable mounting racks enable the angle of the solar array to be changed, keeping it aimed more directly at the sun. Adjusting the tilt angle increases the systems annual energy production by a few percent. The tilts of roof mounted arrays however are rarely changed in that climbing on a roof is usually difficult and dangerous. But changing the tilt angle of pole or ground-mounted arrays can be done quickly and safely. Pole-mounted arrays also can incorporate tracking devices that allow the array to automatically follow the sun across the sky from east to west each day. Tracker arrays can increase the systems daily energy output by 25 to 40 percent in some locations but are more costly
It is an economic necessity in the higher latitudes of the northern hemisphere as in Ohio that solar arrays face south for a cost effective system.
The AC current coming out of the inverter next travels to another disconnect. This disconnect is required by the electric utility companies and is always located in an accessible area usually outside. By switching the current off at the AC disconnect box the utility linemen can stop the flow from the solar array into the utility companies lines. This is essential for safety when utility linemen must execute repairs on the company lines.
The direct current generated by the solar panels travels by wire from the array to a disconnect box. The box is usually located near the array and serves to stop the flow of current from the array. This is primarily a safety measure but also serves to allow repair further down the system.
From the DC disconnect the current travels by wire to the inverter. The purpose of an inverter is to transform the DC electricity into alternating current or (AC) electricity. This is the type of electrical current used in most all residential and commercial functions. In grid-tie-in applications (to be explained below), inverters perform the additional function of synchronizing the electricity they produce with the grid’s “utility grade” AC electricity. This allows the system to feed solar-made electricity into the utility grid.
From the AC disconnect the electricity travels to the breaker panel which it enters through an available breaker. From its entry point into the breaker panel it can flow to all other circuits connected in the panel supplying electricity through out the home or business. If more electricity is being generated than is being used it can also flow from the breaker panel to the utility company.
Line to Home or Business
From the breaker panel a wire or circuit runs to an electric meter. Another wire from the utility company also runs into the meter. The meter measures the amount of electricity flowing in from the utility company which turns the meter forward and the amount of electricity flowing out from the solar array to the utility company which turns the meter backward. Periodically the utility company reads the meter and generates either a bill or a payment.
The solar power system that has been explained above is the type of system referred to as grid-tie-in or net metering. Grid-tie-in means that the personal solar array or wind turbine generated electricity is connected to the supply from the utility company. This leaves the user with two sources of supply, the utility company and their wind or solar electric generating system. Grid-tie-in has several advantages over a stand alone battery system. Excess production from the solar panels or wind turbine can be sold to the utility company for the same price it would be bought for until the meter reads zero and a much lower price unfortunately thereafter. Sufficient electricity is always available night or day (except in the case of a utility company power failure). It helps to minimize errors from design use estimates and natural production variation and will accommodate new demand not figured in the initial estimate of the solar or wind generating system.
Alternative energy from solar and wind can also be stored in batteries without being tied into the utility company grid. Such systems are called “stand alone”. They have the advantage of supplying power any time even when the sun is not shining, the wind is not blowing, and the utility company power is down. However, they are more expensive primarily because of the cost of batteries and are limited in their capacity to supply power.
Line to the Utility Company