BEFORE GOING SOLAR
HOW SOLAR WORKS
There are a variety of solar PV technologies available for your home or business. Read below to learn more.
Solar electric systems, otherwise known as photovoltaic (PV) systems, convert sunlight into electricity. Solar cells, the basic building blocks of a PV system, consist of semiconductor materials. When sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms. This phenomenon is called the "photoelectric effect." These free electrons then travel into a circuit built into the solar cell to form electrical current. Multiple solar cells are included in solar modules, which are wired together into an array that will generate electricity for your home. Only sunlight of certain wavelengths will work efficiently to create electricity. PV systems can still produce electricity on cloudy days, but not as much as on a sunny day. For more about the basics of PV, visit the Department of Energy, NREL, EIA, and Solar Technologies Program websites for more solar energy resources.
Most PV systems today connect to the local utility system so the consumer can still receive electricity from the grid to power their home at night. Net Metering allows the consumer to send any excess electricity generated during the day from the consumer's solar system back out to the grid in exchange for credits. Using the free electricity from your solar system will lower your electric bills and decrease your carbon footprint.
PV panels produce DC electricity, which is converted into AC power by an inverter. Generally there is only one inverter for an entire array of panels, but some systems have a newer technology called micro-inverters where each solar panel feeds into a small inverter. Micro-inverters are more efficient, although they can also be more expensive. A similar new technology is ‘DC optimizers’, which provide similar efficiencies and panel-level monitoring but are connected to a central inverter. Appropriate technologies vary depending on the application, and you should consult with a certified solar installer to decide what is right for your needs.
The performance of a solar cell is measured in terms of its efficiency at converting sunlight into electricity. There are a variety of solar cell materials available, which vary in conversion efficiency.
A solar cell consists of semiconductor materials. Silicon remains the most popular material for solar cells, including these types:
* Monocrystalline or single crystal silicon
* Multicrystalline silicon
* Polycrystalline silicon
* Amorphous silicon
The absorption coefficient of a material indicates how far light with a specific wavelength (or energy) can penetrate the material before being absorbed. A small absorption coefficient means that light is not readily absorbed by the material. Again, the absorption coefficient of a solar cell depends on two factors: the material making up the cell, and the wavelength or energy of the light being absorbed.
Thin film solar cells use layers of semiconductor materials only a few micrometers thick. Thin film technology has made it possible for solar cells to now double as these materials:
* Rooftop or solar shingles
* Roof tiles
* Building facades
* Glazing for skylights or atria.
Thin-film rooftop or solar shingles, made with various non-crystalline materials, are just now starting to enter the residential market. The following are benefits of these solar shingles:
* Attractive integration into homes
* Dual purpose: serves as both roofing material and electricity generator
Commercially-available solar shingles generally have lower efficiencies and greater expense compared with the standard small solar electric system.
Every solar project should begin with an energy audit, which your installer generally provides. A basic energy audit is required in order to receive NYSERDA incentives for PV projects. Energy efficiency measures can help to maximize the financial and environmental benefits of investing in solar by substantially reducing your base energy load. There are many ways you can reduce electricity use in your home and help reduce your energy bills.
Energy Efficiency Resources
Department of Energy
NYS Utility Energy Efficiency Programs
- Residential and Non-residential
- The Appliance Recycling Program is a residential energy efficiency program to reduce energy use by removing less-efficient refrigerators and freezers from residence
- Commercial Lighting
- The Company uses electric and hybrid vehicles
- Promote purchasing such vehicles and installing Level 2 chargers
- Rebates - Con Edison provides rebates of up to $1000 on select high-efficiency equipment
- Free Professional Consultation on Energy Usage
- Free Thermostat - Comes with $50 check
- Neighborhood Program - “Our Neighborhood Program delivers energy-saving and management solutions to local communities where the demand for electricity is expected to grow significantly because of the vitality in businesses and housing markets.”
- Free Professional Consultation on Energy Usage - May include free services and rebates
- Rebates - Energy Efficiency Incentives
- Demand Response Program - “Con Edison's demand response programs pay over 800 participating customers who are able to temporarily reduce electric usage when requested by Con Edison.”
- Demand Management Incentives - “The Demand Management Program offers enhanced incentives for energy efficient technology that will help improve operational performance of buildings and reduce electric demand.”
- Residential Energy Affordability Partnership - Free Inspection and Installation for eligible customers
- Energy Partner Agreement - “The PSEG Long Island Efficiency Partner list is made up of contractors, distributors, suppliers and manufacturers of energy efficient equipment. The list also includes skilled professionals such as architects, engineers and energy consultants that assist PSEG Long Island in meeting their energy savings goals.”
- Energy assessments, Natural gas conversions, rebates and more
- Small Business - Direct Install and Custom Directed Options
- Medium-to-Large Businesses - “National Grid will help to identify and prioritize energy saving opportunities and provide technical services that will facilitate the installation of premium energy efficient equipment in your facility. “
- Rebate - Replacing old equipment with high efficiency natural gas equipment
- Multifamily Energy Efficiency Program - Equipment replacement and rebates
- Small Business - Free Assessment and 70% cost covers
- Commercial/Industrial - Webinar training and rebates
- Non-residential multi family - Equipment replacement and rebates
Orange and Rockland
- Appliance Recycling - $50 payback for refrigerator/freezer
- Electric Appliance Rebates - $10-$50 if you purchase an ENERGY STAR air conditioner or dehumidifier.
- Gas Appliance Rates - $2,050 in rebates from O&R for high efficiency replacement
- Gas Conversion Rebates - Natural Gas switch for $500 rebate
- Commercial and Industrial Programs - Prescriptive and Custom rebates for installation of high-efficiency equipment
- Small Business Program - “Business owners can get a free energy survey and upgrade their lighting for 30% of the installed costs.”
- Demand Response Program - “O&R customers who participate in a demand response program can get paid to use less energy.”
Rochester Gas and Electric (Share many programs with NYSEG)
- Free Energy Saver Products
- Refrigerator/Freezer Recycling
- High Efficiency Natural Gas Equipment Rebates
- Local Wind Energy Program
- Demand Response Program -”Our Demand Response programs offer incentives to select residential, small business and industrial customers businesses when they reduce electricity use during times of peak demand”
- Residential Agricultural Discount - Discount on energy bill
- Energy Efficiency- Partnered with NYSEG
In hot and sunny regions, solar thermal systems can be a great decision. But even in New York's relatively cold climate, solar water heaters can provide year-round hot water for homes and swimming pools.
The economics of solar water heaters depend largely on the available incentives and on the type of fuel being displaced. For example, a customer that has an expensive source of energy to heat their water, such as electricity or propane, will receive greater benefits from going solar than a customer using relatively lower cost natural gas. For more information on solar thermal systems, NY incentives and installers, please visit the NYSERDA Website.
HOW THEY WORK
Solar water heating systems include storage tanks and solar collectors. There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don't.
Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.
Three types of solar collectors are used for residential applications:
Glazed flat-plate collectors are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors (typically used for solar pool heating) have a dark absorber plate, made of metal or polymer, without a cover or enclosure.
Integral collector-storage systems
Also known as ICS or batch systems, they feature one or more black tanks or tubes in an insulated, glazed box. Cold water first passes through the solar collector, which preheats the water. The water then continues on to the conventional backup water heater, providing a reliable source of hot water. They should be installed only in mild-freeze climates because the outdoor pipes could freeze in severe, cold weather.
Evacuated-tube solar collectors
These feature parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin's coating absorbs solar energy but inhibits radiative heat loss. These collectors are used more frequently for commercial applications.
SOLAR THERMAL APPLICATIONS
Low Temperature (> 30C)
–Swimming pool heating
–Ventilation air preheating
Medium Temperature (30C – 100C)
–Domestic water and space heating
–Commercial cafeterias, laundries, hotels
–Industrial process heating
High Temperature (> 100C)
–Industrial process heating
Solar thermal and photovoltaics working together