INTRODUCTION OF SOLAR ENERGY
Lately, the world has luckily turned out to be progressively cognisant of the critical capability of sun oriented vitality as a trade for non‐renewable energy source vitality. The sun is a spotless, boundless and practically limitless vitality source, giving each hour on earth as much vitality as the entire world needs in a year. Demonstrated advances can change its radiation into warmth, power and even cool, and are presently to a great extent accessible at moderate costs. It is generally perceived as dependent solely on hot sunny weather to be effective. In fact, it can be successfully used on cloudy days, as it is the solar radiation which is effective. The average amount of solar radiation falling on a south facing inclined roof is shown to vary between about 900 and 1300 Kw/m2 per year depending on the location. Solar energy has a flat plate ‘black radiator’ solar panel to absorb solar energy in water, which is transferred for storage in an insulated cylinder. Solar energy, in its active or passive forms, is able to deliver the entire set of building energy needs: space heating and lighting, domestic hot water (DHW), electricity, and recently also space cooling.
BLACK BODY THEORY
Black-body radiation is the thermal electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body (an opaque and non-reflective body). It has a specific spectrum and intensity that depends only on the body’s temperature, which is assumed for the sake of calculations and theory to be uniform and constant.
The thermal radiation spontaneously emitted by many ordinary objects can be approximated as black-body radiation. A perfectly insulated enclosure that is in thermal equilibrium internally contains black-body radiation and will emit it through a hole made in its wall, provided the hole is small enough to have negligible effect upon the equilibrium.
As the temperature decreases, the peak of the black-body radiation curve moves to lower intensities and longer wavelengths. The black-body radiation graph is also compared with the classical model of Rayleigh and Jeans.
Solar panels, also known as modules, contain photovoltaic cells made from silicon that transform incoming sunlight into electricity rather than heat. (”Photovoltaic” means electricity from light — photo = light, voltaic = electricity.)
Solar photovoltaic cells consist of a positive and a negative film of silicon placed under a thin slice of glass. As the photons of the sunlight beat down upon these cells, they knock the electrons off the silicon. The negatively-charged free electrons are preferentially attracted to one side of the silicon cell, which creates an electric voltage that can be collected and channel. This current is gathered by wiring the individual solar panels together in series to form a solar photovoltaic array. Depending on the size of the installation, multiple strings of solar photovoltaic array cables terminate in one electrical box, called a fused array combiner. Contained within the combiner box are fuses designed to protect the individual module cables, as well as the connections that deliver power to the inverter. The electricity produced at this stage is DC (direct current) and must be converted to AC (alternating current) suitable for use in your home or business.
SOLAR PANEL USING SOLAR ENERGY
Solar panels convert the sun’s light into using solar energy using N-type and P-type semiconductor material. When sunlight is absorbed by these materials, the solar energy knocks electrons loose from their atoms, allowing the electrons to flow through the material to produce electricity. This process of converting light (photons) to electricity (voltage) is called the photovoltaic (PV) effect. Currently, solar panels convert most of the visible light spectrum and about half of the ultraviolet and infrared light spectrum to using solar energy.
Solar energy technologies use the sun’s energy and light to provide heat, light, hot water, electricity and even cooling, for homes, businesses, and industry.
How does a solar collector work?
A solar collector is basically a flat box and composed of three main parts, a transparent cover, tubes which carry a coolant and an insulated backplate. The solar collector works on the greenhouse effect principle; solar radiation incident upon the transparent surface of the solar collector is transmitted through this surface. The inside of the solar collector is usually evacuated, the energy contained within the solar collector is basically trapped and thus heats the coolant contained within the tubes. The tubes are usually made of copper, and the backplate is painted black to help absorb solar radiation. The solar collector is usually insulated to avoid heat losses.
Energy Storage Systems
Combining energy storage with both renewable and traditional power sources will output clean, conditioned, and uninterrupted AC power. Energy storage with energy management technology provides economic benefits while protecting critical necessities.
A Solar Energy System with Energy Storage Will…
- Provide Emergency Power During Electrical Outages
Although electricity produced by a solar system will reduce your dependence on the utility grid during the day and save you money, grid-tied systems will automatically shut off during a utility blackout, as required by law. If your system isn’t tied to the grid, it is still impractical to rely on it exclusively as your source of electricity during an electrical blackout due to its intermittent production of electricity, even on a sunny day.
However, if that intermittent solar electricity is sent to an energy storage unit (or battery bank) to be saved during high production periods, the unit can provide a seamless source of quality electricity to the home throughout the entire day or at night if there’s a power outtage.
- Reduce Your Dependence on the Electric Grid
Besides being able to take advantage of the free electricity generated by your solar modules during the day, you can also utilize the battery bank to supply your home’s power during “on-peak” hours to save money.
The batteries, which are recharged from the solar array or from the grid during “off-peak” periods, can be used to eliminate expensive electricity rates during “on-peak” periods.
Additionally, New Jersey’s Net Metering law enables you to transfer excess energy from your solar system to the grid for credit (and spin your meter backwards).
- Enable You to Manage Your Electrical Usage
The operation of the energy manager is primarily controlled through two modes to ensure that you are best covered for your current and future situations.
The first specifically reduces “on-peak” usage by using the batteries to supply power to the home during the day.
The second mode will conserve battery power in anticipation of a power interruption.
In the event of a utility failure, the system will automatically sense the outage and supply your home with power within milliseconds, limiting the electrical usage to essential circuits.
- Allow You to Monitor & Control Your Electrical ConsumptioN
The system’s monitoring gateway requires no land-line or internet connection; instead, its signal travels wirelessly using a dedicated, encrypted and secure connection to allow you instant access to the system’s performance.
Just log in from your computer or mobile phone and you’ll find current, detailed activity reports regarding the system’s energy consumption, solar production, battery charge, daily electrical usage, energy use, and weather forecasts stored securely online.
When trouble strikes and the system’s activity becomes altered, the system interacts with the central station to send out an immediate alert via email or text message.
How Energy Storage Works
Because an energy storage system combines renewable and traditional power technologies, it can operate in different modes under various circumstances to provide your home with the most cost effective and energy efficient outcome.
On Sunny Days
The solar panels will fully charge the batteries and provide free solar electricity throughout the home. Any surplus electricity generated by the solar system will be sent to the utility grid, turning your meter backwards, for credit.
On Cloudy Days
If the solar panels are unable to generate electricity during “on-peak” periods, power will be supplied from the battery bank to conserve energy costs.
At night, during “off-peak” periods, electricity from the utility is used to power the house and recharge the batteries.
During a Utility Brownout
Rain or shine, the system will immediately sense the power disturbance and start distributing electricity from the solar panels or batteries. The system will limit electric usage within the house to selected circuits and also ensure that quality power is provided to motorized appliances.
During a Utility Blackout
The system will automatically respond to the power failure and distribute electricity from the solar panels or batteries to essential circuits throughout the house.
House appliances using solar energy
Solar Hot Water Heater
Solar hot-water heaters are becoming popular appliances. A set of photovoltaic panels captures heat energy from the sun to heat water for bathing, washing dishes, and other household uses. The units can be direct or indirect. A direct water heater passes heat energy directly into an insulated water tank, where it is then pumped throughout the home. Indirect systems use a series of refrigerant-filled tubes to transfer heat energy into the home, where it is then used to heat the water. Direct systems work best in areas that rarely experience freezing temperatures, while indirect systems can be used in almost any type of climate.
According to the American Council for an Energy Efficient Economy, solar hot-water heaters cost about $175 a year to run, compared to $350 for a traditional gas-fired storage water heater. Best of all, solar systems generally feature an electric backup that operates if solar power is interrupted or insufficient.
Traditional solar panels could be used to provide heat to the home, but were not designed to power appliances. Modern photovoltaic panels use a slightly different method of collecting solar energy, and can produce enough electricity to power every appliance in the average home. Homeowners install these panels on roof or ground racks, where they collect solar energy whenever the sun is shining. This energy passes through a series of wires into a transformer, where it is converted into the standard 110 volts used in the home. Excess energy is stored outdoors in a battery backup, which provides power even when the sun isn’t shining.
Installers can help you choose the correct quantity and type of photovoltaic panels based on the electrical demands of your home. If you have limited space available, you can use smaller panels to power individual appliances through a dedicated circuit.
A solar oven is a cooking appliance that runs entirely on solar energy. It contains mini-solar or photovoltaic panels to collect and absorb heat energy from the sun. Using this heat, the oven can cook almost any type of food. Solar ovens provide a slow-cooking process similar to a Crock pot, and can only be used outdoors. Using an optional reflector, users can increase the temperature of these ovens up to 400 degrees, which means that cooking can be completed much more quickly.
Solar flashlights feature solar photovoltaic panels which collect energy-intensive sunlight, ambient light, and even artificial light, before converting it to electrical energy. This energy then powers the bulb, which is often an extremely powerful and durable LED bulb. You’ll never need to replace batteries, which cost money and are hard to dispose of in an environmentally friendly You’ll never need to replace batteries, which need to be replaced and are difficult to dispose of in an environmentally friendly manner. Plus, they work in extreme temperatures — something most battery-operated appliances fail to do.
Of course, you need a source of light in order to power them, and their beam isn’t always as wide or as strong as battery-operated flashlights. But they can be left for long periods of time without worrying that the battery will die.
Solar chargers offer the advantage of powering a wide range of appliances with free, green sunlight via small, easily transportable solar panels. There is a range of solar chargers on the market with the ability to charge pretty much any portable device, including smartphones, tablets, laptops, and GPS devices. Not only are solar chargers a cheaper and greener way of powering up your portable devices, they give you the ability to charge your appliances on the go, wherever you are. Of course, an alternative to investing in solar powered appliances is to install solar panels on your home in order to power your entire house with the energy of the sun. Investing in solar power will lower your carbon footprint, save you money in the long term, and give you the satisfaction of knowing that your home is powered by nature.
TYPES OF SOLAR ENERGY FOR HOT WATER SYSTEM
The solar energy for hot water system is using a solar panel that is heat the water through a storage tank. Solar energy for hot water system also known as solar water heater or solar domestic hot water systems. This system is a cost-effective way to generate a hot water for us because it fuel is an energy supply by sun. There are two different type of solar energy hot water system which is as below:
- Active solar water heating system
In active solar water heating system, it is contained the circulating pumps and controls which is it reaction are differently by its type. Active solar water heating system divided into two another type which is:
- Direct circulation systems
The pumps are circulating the household water through the collectors and into the home.
*WORK WELL IN CLIMATES THAT RARELY FREEZES
- Indirect circulation system
The pumps are circulating a non- freezing water, which is it heat- transfer fluid through the collectors and heat exchanger. This heat will make the water heat and then flows to the home.
*USUALLY USED AT THE CLIMATES PRONE TO FREEZING TEMPERATURES
2. Passive solar water heating system
Passive solar energy is divided into basic types which is as below:
- Integral collector- storage passive system
Integral collector- storage passive system usually used in the areas where the temperatures are rarely fall below the freezing because it is work well in the households with significantly in daytime and evening when the hot-water needs
2. Thermosyphon system
This type is using a water that flows through the system when warm water as cooler water. In this system, the collector should be installed below the storage tank so that the warm water will rise into the tank.
INSTALLING AND MAINTAINING THE SYSTEM OF SOLAR ENERGY FOR HOT WATER
- To install the system of solar energy for hot water are depends on many factors. These factors are including as below:
- solar resource
- local building code requirements
- safety issues
- After installation, you should properly be maintaining your system to keep it running smoothly.
- Plumbing and other conventional water heating components require the same maintenance as conventional systems.
- Glazing may need to be cleaned in dry climates where rainwater doesn’t provide a natural rinse.
- Regular maintenance on simple systems can be as infrequent as every 3–5 years, preferably by a solar contractor.
- Systems with electrical components usually require a replacement part or two after 10 years.
COMPONENT OF HOT WATER SYSTEM
Allows air that has entered the system to escape, and in turn prevents air locks that would restrict flow of the heat-transfer fluid.
- TEMPERATURE-PRESSURE RELIEF VALVE
Protects system components from excessive pressures and temperatures. A pressure temperature relief valve is always plumbed to the solar storage (as well as auxiliary) tank.
Protects components from excessive pressures that may build up in system plumbing. In any system where the collector loop can be isolated from the storage tank, a pressure relief valve must be installed on the collector loop.
Is used in indirect systems to monitor pressure within the fluid loop. In both direct and indirect systems, such gauges can readily indicate if a leak has occurred in the system plumbing.
Admits atmospheric pressure into system piping, which allows the system to drain. This valve is usually located at the collector outlet plumbing but also may be installed anywhere on the collector return line.
These valves are used to manually isolate various subsystems. Their primary use is to isolate the collectors or other components before servicing.
Used to drain the collector loop, the storage tank and, in some systems, the heat exchanger or drain-back reservoir. In indirect systems, they are also used as fill valves.
Allow fluid to flow in only one direction. In solar systems, these valves prevent thermosiphoning action in the system plumbing.
Are set to open at near freezing temperatures, and are installed on the collector return line in a location close to where the line penetrates the roof.
Provide an indication of system fluid temperatures.
Installation – Roof
Every roof structure that solar collectors will be mounted on must be carefully inspected for structural integrity. Depending on your location, many permitting authorities will require an in-depth description and possibly an accurate analysis of the load carrying capacity of a roof where solar collectors will be mounted.
- All non-residential buildings over 50,000 cubic feet that will have solar collectors mounted on them will require a set of approved plans in order to receive a building permit.
- Document the construction of the roof. Most municipalities will require structural information about buildings where solar collectors will be mounted on them in order to receive a building permit. The more information you can collect about the structure of the building will help facilitate this process. Some municipalities will require calculations to show that the weight loading of the solar collector array will not adversely affect the building structure
Installation – Awning Mount
Where the collector array is hung on a wall, the wall must be strong enough to hold the weight of the collectors and racking.
- Distribute the weight over as many building framing members as possible. Unistrut-type racking bolted to the framing members can distribute the weight evenly on the wall.
- Do not just bolt/screw fasteners into the sheathing alone, bolt/screw into the framing members of the wall.
- If the wall has a brick veneer, the racking must pass through the veneer to the wall framing members behind the brick.
Most flat plate collectors cannot be hung from the top rail of the collector because the collector was not designed to be mounted in this way.
- To strengthen a flat plate collector so it can be hung from its top rail, install two pieces of aluminum angle iron connecting the top rail to the bottom rail, spaced one foot in from each side. This will hold the collector together.
- Another method is to install a rack to the wall and then flush mount the collectors to the rack.
Installation – General
- Use water-soluble flux.
- Rinse solar loop with cold, then hot water until clear (with boiler cleaner added), then follow with a hot then cold water rinse before filling solar loop with solar fluid. This will clean out any dirt, oils and flux residues.
- Use only “Solar Rated” Propylene Glycol. The temperature rating should be at least 320°F continuous.
- Check glycol with refractometer after filling to ensure proper freeze protection.
- Dilute glycol with distilled or de-mineralized water only.
- If using a water-only drainback, use distilled or de-mineralized water as the solar fluid.
- Do not use di-electric unions on stainless steel storage tanks.
- If piping travels down the side of a house, consider using vinyl two-piece chase.
- Properly seal rim joist penetrations.
Installation – Controller
- Ground collector array and piping with a continuous length of ground cable, no splices. Terminate ground at main electrical panel ground lug.
- Collectors and solar loop piping must be properly grounded as per NFPA 780 (national standard for lightening protection systems)
- Use proper size and type of sensor wire.
- Use jacket sensor wire that is rated for outdoor use
- Required: twisted wire (#18 minimum) with a shielded cable.
- Only attach shield to ground lug in controller and trim other end of shield.
- Use watertight connectors or solder connections. Corroded sensor wire splices are a common problem that can be easily remedied.
- Utilize a telecommunications splice as an option.
Installation – Sensors
- Use heavy-duty high temperature-rated sensors.
- The best location for the collector sensor is on top of the upper collector manifold, preferably inside the collector
- If sensor is clamped outside of the collector, insulate very well.
- Where feasible, use immersion wells instead of clamping methods.
- Use heat transfer grease on all sensors.
- Securely clamp sensor to collector and/or tank.
Installation – Heat Exchanger
- Install isolation valves and drain/fill ports on the waterside of the heat exchanger to facilitate cleaning, especially if the heat exchanger is the plate type. Remove the handles on the isolation valves so they will not inadvertently be closed. Hang the handles nearby.
- Insulate heat exchanger well.
- Label the heat exchanger (single or double wall).
Installation – Potable Side of System
- Use a domestic water thermal expansion tank where there is a backflow preventer on the cold -water inlet. Common applications are commercial buildings and well systems (often the well tank is not sized to accommodate extra expansion, especially in large systems) .). Place the expansion tank so there is not a check valve between the storage tanks and the expansion tank.
WATER STORAGE AND DISTRIBUTION
As the sun heats water in the parallel heater tubes, warmed water rises by convection in the tubes and enters the storage tank while cooler water from the tank falls into the tubes for further heating. Heated water is drawn from a fitting at tank top while incoming cool water is fed into the tank bottom. The system heats water and stores it in the reservoir tank using only natural convection with no pump required.
The simplest collector is a water-filled metal tank in a sunny place. The sun heats the tank. This was how the first systems worked. This setup would be inefficient due to the equilibrium effect: as soon as heating of the tank and water begins, the heat gained is lost to the environment and this continues until the water in the tank reaches ambient temperature. The challenge is to limit the heat loss.
- The storage tank can be situated lower than the collectors, allowing increased freedom in system design and allowing pre-existing storage tanks to be used.
- The storage tank can be hidden from view.
- The storage tank can be placed in conditioned or semi-conditioned space, reducing heat loss.
Drainback tanks can be used.