POWER OF THE SUN

Photovoltaic

In this first section, we hope to simplify the questions of:

What is Photovoltaic?

How does Photovoltaic work?

What companies make the products necessary?

How much does it cost?

Who can install the system?

Can I really sell back any excess power to the local utility?

Many people assume that installing a photovoltaic (PV) system is restricted to sunny climates and regions. Obviously, sun resources are important, but PV systems aren't only a solution for sunny states and regions. They are being used more and more here in New England. Solar thermal and photovoltaic devices depend basically on sunlight (and not on temperatures).

 What is Photovoltaic?

How does a Solar PV (Photovoltaic System Work?

Solar panels installed on the roof or elswhere convert sunlight into electricity.

Typically, you'll need a south-facing roof that is not shaded by trees or other obstructions. There is a device (called a Solar Pathfinder) that can tell if shade is present on your roof at any time of the year.

This power from the solar panels, generated as Direct Current, is sent to a device called an inverter.

An inverter has several jobs.

1- It converts the Direct Current from the solar panels into Alternating Current, which is what your household appliances use.

(Some systems, such as 'off-grid' systems in houses that are too remote for the utility to reach do not need an inverter because all of their devices run on direct current).   

2 - The Inverter sends the electricity to the main circuit breaker panel in the house. From there, the electricity can go into the house to run appliances or, if there is more electricity being generated than is being used, it will go back into the utility grid. If permitted by local Net-Metering laws, this will spin your electrical meter backwards ... effectively selling power back to the utility.

3 - The inverter 'watches' the utility grid so that it can shut down, immediately, if the utility grid shuts down. This way, if a storm or accident breaks an overhead electrical wire then your solar system will not send power into the electrical system and endanger people. Photovoltaic PV solar systems will keep your lights on during a power failure if you have batteries attached to the system.

What does it cost???

Prices depend mainly on the Watts/Volts needed to power the home. The amount of power needed will be translated into the number of panels needed, and that the more standard wattage in panels is around 150-200 Watts. An average home would be 3.4 to 10KW.

The price of a PV system is often in the range $30,000 - $60,000 per home, but rebates and tax incentives may reduce that price significantly. There are several programs for Connecticut residents both State and Federal, that homeowners can take advantage of today. Cost could be covered up to 50%.*

*This does not include tax savings.

(See web links for connection to those programs)

Who makes the panels/ equipment I need?????

PV solar panels (for the production of electricity) are manufactured by major world corporations: Sharp, Solar World (Shell), Sanyo Photovoltaics, Mitsubishi Solar, Kyocera Solar, GE Energy, etc.

Here is a list of Manufacturers:

Advent Solar  Amonix Inc Atlantis Energy System Inc. B P Solar Int'l LLC Canrom Photovoltaics, Inc. DayStar Technologies Inc. Energy Photovoltaics Inc, Evergreen Solar Inc. First Solar Llc. GE Energy (USA) LLC Global Solar Energy Inc. Innergy Power Corporation, Iowa Thin Film Technologies Kyocera Solar Inc. Matrix Solar Technologies

Mitsubishi Electric & Electronics USA, Inc. Mitsui Comtek Corp. Pacific SolarTech RWE Schott Solar Inc. SANYO Energy (USA) Corporation Sanyo Semiconductor Corporation Sharp Manufacturing Company of America Shell Solar Industries LP Solar Power Industries, Inc. Spire Corporation Sunpower Corporation Sunwatt Corporation Sunwize Technologies LLC Terra Solar Global, Inc. Tideland Signal Corporation United Solar Ovonic LLC

What is net metering?

"Net-metering" is a simplified method of metering the energy consumed and produced at a home or business that has its own renewable energy source. Under net metering, excess electricity produced by the source will spin the existing home electricity meter backwards, effectively banking the electricity until it is needed by the customer. This provides the customer with full retail value for all the electricity produced. Net metering simplifies this arrangement by allowing the customer to use any excess electricity to offset electricity used at other times during the billing period. In other words, the customer is billed only for the net energy consumed during the billing period.

What are the benefits of net metering?

Net metering provides a variety of benefits for both utilities and consumers. Utilities benefit by avoiding the administrative and accounting costs of metering and purchasing the small amounts of excess electricity produced by renewable energy source. Consumers benefit by getting greater value for some of the electricity they generate and by being able to interconnect with the utility using their existing meter.

 Can I really use my existing meter to take advantage of net metering?

The standard kilowatt-hour meter used for most residential customers accurately registers the flow of electricity in either direction. This means the ‘netting’ process associated with net metering happens automatically — the meter spins forward (in the normal direction) when the customer needs more electricity than is being produced, and spins backward when the customer is producing more electricity than is needed in the home or building.   

Net Metering Rules in Connecticut

Incentive Type:	Net Metering Rules
Eligible Renewable/Other Technologies:	Solar Thermal Electric, Photovoltaics, Landfill Gas, Wind, Biomass, Fuel Cells, Municipal Solid Waste, Small Hydroelectric, Tidal Energy, Wave Energy, Ocean Thermal
Applicable Sectors:	Commercial, Industrial, Residential, General Public/Consumer, Nonprofit, Schools, Local Government, State Government, Fed. Government, Multi-Family Residential, Agricultural, Institutional
Limit on System Size:	2 MW
Limit on Overall Enrollment:	None stated
Treatment of Net Excess:	Credited to customer's next bill at retail rate; generally purchased by utility at avoided-cost rate at end of 12-month billing cycle
Utilities Involved:	Investor-owned utilities
Interconnection Standards for Net Metering?	Yes
Authority 1:	Conn. Gen. Stat. § 16-243h
Date Enacted:	1998 (subsequently amended)
Effective Date:	7/1/1998

The ABC's of SOLAR

Cell	A solar cell is the basic component in the manufacture of solar modules. Cells are manufactured from wafers.
CO2	An abbreviation for carbon dioxide. A pollutant created by power station production. With a solar power system, within a few years more CO2 is saved than was emitted for the production of the solar modules.
Grid Connected	A “grid-connected” solar electric system generates its own electricity and feeds its excess power into the utility grid for later use. Only grid-connected solar electric systems are eligible for many incentives and rebates.
Inverter	This is a complex electronic based power product that converts DC power into AC power and is required for solar power systems.
kWh	An abbreviation for kilowatt hours. One kWh represents 1,000 watts over a period of one hour. Electricity rates are most commonly expressed in cents per kilowatt hour.
Million Solar Roofs Initiative	This is an initiative to facilitate the installation of solar energy systems on one million US buildings by 2010. Increasing the demand for solar electric systems in the US will lower the cost.
Module	Describes a unit composed of several solar cells that can be electrically connected, encapsulated in tempered glass and framed.
Monocrystalline	Silicon that is pulled as a single crystal. The internal crystalline structure is completely homogenous, which can be recognized by an even external coloring.
MW	An abbreviation for megawatt. This term is used to measure the power of solar systems. 1 MW = 1,000 kW.
Net	Metering Net-metering allows the solar electric system to send excess electricity back through the electric meter to the utility. The meter actually runs backwards! Your utility will credit the excess power produced at the same rate paid for electricity purchased.
Photovoltaics	A physical effect causing a voltage to be generated across two electrical poles of a semiconductor plate and allowing current to flow when connected to a receiver. Photo (Greek) = photos: light; Volt = unit of electrical potential Voltage through light.
Polycrystalline	This is a crystalline structure of silicon where several crystals form in a mold. Polycrystalline cells can be recognized by a visible grain, a “metal flake effect”.
Silicon	The basic material used to make solar cells. It is the second most abundant element in the earth’s crust, after oxygen.
Stand-alone system	When generated energy is stored in batteries and then subsequently used. These systems are not connected to the utility grid.
Wafer	A sawn silicon disc, used as the starting point for manufacturing a solar cell.

SOLAR WATER HEATING

The system for solar water heating has 2 primary pieces; the collector and the storage tank.

Solar water heaters can be either passive or active. Today active systems are the most common.

ACTIVE

The active solar water heater uses electric pumps and controllers to circulate water or fluids.

There are two types of circulation systems used with active solar water heaters; direct and indirect.

INDIRECT circulation systems pump glycol fluids through the collectors. The heat exchanger removes the heat from the fluid to the potable water.

DIRECT circulation systems use the potable water. With the use of an electric pump the potable water is circulated through the system passing through the collectors to be heated.

PASSIVE

Passive solar water heaters do not use electric pumps. They rely on gravity.

There are two types of passive solar water heaters; Thermosyphon collector storage systems and Integral collector storage systems

THERMOSYPHON collector storage systems first heat the water in the solar collector. As the water reaches temperature it naturally rises into the storage tank (usually placed above the collector, some applications put it in the attic).

INTEGRAL collector storage systems start with one or more storage tanks placed facing the sun.