All Things HVAC

Heating and Cooling HVAC information for Everyone

Solar Power

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Solar Power
By Betty Stephens

Solar panel

Today human’s energy production is derived mainly from fuels, such as coil, oil and gas. Most of that energy is the sun’s stored energy. Sunlight is actually the Earth’s primary source of energy. Solar Power is the energy generated by sunlight. Solar energy is being increasingly adopted throughout the globe because of its environmental benefits. This type of energy produces no waste and does not give out any harmful emissions. Also, it does not put a strain on the Earth’s ecosystem by using up too much land.
The amount of energy generated by photosynthesis about six times larger than the whole human power consumption. There are two ways to convert sunlight into electricity: directly or indirectly.
1. Direct conversion is achieved by using Solar Panels. The solar panels are constructed with silicon PV cells/ Solar Panels can be installed on the ground, on countryside houses, or massive power plants, or on rooftops.

2. Indirect conversion is achieved by concentrating sunlight using lenses or mirrors to generate heat. The heat is then transferred to a transfer fluid for a conventional power plant or it can even be combined with PV arrays to improve their efficiency. It is the same basic process as using a magnifying glass to burn something.
How Solar Panel Work
Solar cells work because of the tendency of certain natural materials, called semiconductors, to convert light energy into an electric charge. Each cell produces a small voltage, and when you connect many cells together in a panel, their voltages add together to produce enough electrical power for home or industrial use. Solar panels produce free energy, but their production and installation involve significant expense.

Solar panels produce a DC voltage that fluctuates with the intensity of the impinging sunlight. To use this voltage to charge a battery, you have to regulate it and match it to the battery voltage by connecting the panels to the battery via a charge controller. This controller not only regulates voltage, it also monitors the batteries and disconnects the current when they are full to prevent overcharging. In order to use the DC current from the batteries in your house, you must route the electricity through an inverter, which converts it to usable AC current.
To approximately measure the efficiency and solar power output of your installation you can use one of the available online solar calculators. They can provide you with a rough estimate of your need.

Solar Calculators
1. PVWatts is the standard and most accepted one inside the solar community. A tool developed and hosted by the National Renewable Energy Laboratory.
You can use the following link: PVWatts map viewer
There you can either pick your location by using the map or directly entering your ZIP code. When found, you should click the “Send to PVWatts” button.
Then you will be sent to the PVWatts Calculator page where you will be asked to fill in some details corresponding to your hypothetical PV array setup. The application is well documented and provides help for every field.
2. Solar Estimator is a very good application from solar-estimate.org that has a wider variety of options such as solar hot water systems and solar spa/pool heating. You can test it by clicking this link. The approach is different from PVWatts since it returns the necessary setup to provide a determined percentage of your electrical consumption. The information output is complete, showing charts and lots of useful data.
1. Find Solar Calculator is an application similar to the Solar Estimator with much less output information but with interesting data like carbon emission savings. You can test it by clicking this link.
2. The rest. Most contractors’ website have their own solar calculators.
When considering installing your own PV solar system, speak to a qualified and licensed solar professional about your specific situation. Keep in mind the following benefits. Advantages:
• Free Energy – The sun provides the “fuel” to generate power for the home’s electrical system and components. This saves money on electricity bills
• Clean Energy – Electricity generated by the sun produces no harmful emissions. This reduces the home’s carbon footprint.
• Installation Incentives – Federal, state and local jurisdictions periodically offer grants, tax breaks, discounts and rebates for the installation of renewable energy products, including solar systems.
• Reduced Dependency – Generating your own solar power using panels on your roof means you are not as dependent on utilities and the electric power grid to provide your electricity.
Disadvantages:
• Inconsistent Fuel Source – The sun doesn’t shine 24 hours a day. Some locations have trees or taller buildings that could shade your roof.
• High Initial Cost – Even with multiple incentives, a solar power system may still cost tens of thousands of dollars.
• Site preparation – If the system is a retrofit (not part of new construction, but built on to an existing structure), expenses related to reconfiguring the house’s electric system will be necessary.
• Maintenance – Generating your own electricity means that the upkeep of the system is in your hands

How solar works

Electric Bills & Air Conditioning

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How Much Of Your Electric Bills Is The A/C Unit?
By Betty Stephens

electric bill

Do you ever wonder how much it costs to run your air conditioning (A/C) unit? There are simple calculations that can help you decide how much your AC is costing. People are always surprised to see how much their monthly electricity costs. Here is an example of the cost to operate an in-room air-conditioning unit for a day and for a month. In general, the higher the BTU rating, the more electricity your unit pulls. And, of course, the energy draw varies by make and model.
The average air conditioner in the U.S. today is approximately 3 tons with a 10 SEER efficiency rating. A unit this size draws approximately 2.94kW per hour. To get the approximate cost to run per hour, you simply multiply this number by the cost of electricity per kilowatt hour. In the San Diego area, electricity costs can vary a great deal depending on the time of day that you are using your air conditioning system—from .147 cents per kilowatt hour at baseline costs to more than .29 cents per kilowatt hour at peak usage. For the sake of convenience we’ll simply use the baseline energy cost of .147 cents per kilowatt hour. Now the math:
2.94 x .147=.432 cents per hour during standard demand or roughly double during peak demand. Assuming 1,200 summer cooling hours, your total cost to run a 3 ton 10 SEER AC for a year can range between $516 and $1,023.   If your air conditioner has a SEER rating below the 10 SEER used in this example, your air conditioning costs will be higher. For example, if you have an 8 SEER air conditioner, your system is 20 percent less efficient than a 10 SEER unit, so your cooling costs will be approximately 20 percent higher. If the air conditioner in a home or business is less than 10 SEER, it could be costing hundreds—even thousands of dollars annually.
Understanding Kilowatt-Hours
The kilowatt-hour (kWh) is the standard unit of measurement for electricity in the United States. This is 1,000 watts of electricity being used for one hour. To calculate how much your air conditioner costs to run for an hour, look for its wattage on the box or in the instruction manual and multiply this by the number of hours you use it each day. For example, a 1,000-watt air conditioner running for one hour consumes 1 kWh. By comparison, a 60-watt light bulb running for an hour uses 0.06 kWh (60 watts divided by 1,000). The cost of electricity varies by region. While the average cost in the US in 2011   was 12 cents per kWh, it was as high as 33 cents in Hawaii and as low as 8 cents in Idaho. Check your electric bill to determine your cost.

Calculating Electricity Costs for A/C
To calculate your window air conditioner’s energy use, divide the BTUs by the SEER rating. This gives you the watts per hour. Divide that by 1,000 to get kilowatt hours (kWh), which is probably how your electric company calculates your energy bill. You can then multiply the kWh by your power company rate to learn your costs per hour. For example, a 12,000 BTU air conditioner with a SEER rating of 10 and a cost of 25 cents per kWh would calculate as follows:
12,000 BTUs / SEER 10 = 1,200 W = 1.2 kWh
1.2 kWh x $0.25 = $0.30 per hour to run your window air conditioner. At 8 hours a day for 125 days of summer, your window air conditioner will have an annual running cost of $300 a year.
Cutting Costs
A programmable thermostat can reduce the cost of central air conditioning if you program it at a higher temperature while you are at work and while you are sleeping. The temperature you set the air conditioning at should be relative to the outside temperature. If the temperature outside is 90 degrees, setting the air conditioning to 78 should feel quite comfortable in comparison. Drawing the blinds during the day and opening windows at night when it is cool can also save you money. When purchasing an air conditioner, look for Energy Star units, which use up to 14 percent less energy than government requirements and may entitle you to a tax credit of up to 30 percent of its cost.

electric bill