Estimate Savings From Solar Power Installation

How to Estimate Potential Costs Savings from a Solar Power Installation

Renewable energy for home owners is growing in popularity, with more and more solar panels especially appearing on the rooftops above residential areas at an increasing rate. There is, however, still a big question for a lot of people thinking about investing in solar power – is it worth it? There are two main advantages to installing solar panels – the savings in your utility bills and the reduction in your carbon footprint. The potential savings for both of these come down to the amount of electricity you use which a solar panel array could replace; the less electricity you need to buy from your utilities provider, the lower your bill and the less CO2 emissions you will be responsible for.

Calculating Potential Electricity Generation

The first step to estimating potential cost savings, therefore, is estimating how much electricity you could generate from a solar power array on your house. To do this we need three pieces of information – the average solar radiation in your area, the typical conversion efficiency of a solar panel and the available surface area for the panels.

There are several types of solar panels available, but the two most commonly used for residential installations are Poly and Monocrystalline solar panels. Monocrystalline are slightly more efficient than polycrystalline panels and are increasingly becoming the work-horse option for residential use. They convert available sunlight at an efficiency of around 10%. That is to say that for every 1kWh of available energy coming from the sunlight the panel is exposed to, the panel will be able to generate about 0.1kWh of electricity.

The available solar radiation varies depending on how close you are to the equator and what the typical weather conditions are like – lots of cloud is going to mean less solar radiation. With a bit of digging around, you can usually find solar radiation data for just about anywhere in the world. For example, the National Renewable Energy Laboratory (NREL) has detailed maps for the US as well as many other countries. In particular, we’re looking for data on the annual average Kilowatt Hour Per Meter Squared Per day (kWh/m2/Day) based on solar photovoltaic resource potential.

The available surface area for your panels is going to dictate how much sunlight you can gather. Typically this is going to be the available surface area of your most southerly facing roof. If you can’t safely climb onto the roof to measure the surface area, you can measure the length of the house and estimate the height based on that.

So, with these numbers we can estimate the total amount of electricity we can generate in a year by multiplying the surface area by the annual average kWh/m2/Day by 365 by 10% or:

AxSx365x0.1

Where A is the surface area of the roof and S is the annual average kWh/m2/Day.

Estimating Carbon Footprint Reduction

The amount of carbon dioxide produced from generating electrical power from conventional utility companies varies somewhat depending on how the electricity is generated. In Iceland it’s going to be a lot less than in China where the former uses predominantly geothermal power while the latter is highly dependent on fossil fuels. If you live in a country that has a ‘typical’ mix of power generation sources then 1 pound of carbon dioxide per 1 kilowatt-hour of electricity is generally a good rule of thumb. If you want to get more precise, your utility provider or government energy bodies may publish more specific figures.

In any case, now that we know how much electricity our solar array could potentially produce, working out our carbon footprint reduction is as simple as multiplying the carbon cost of 1kWh of energy by the total amount of electricity we estimate we can produce per year.

Estimating Potential Cost Savings

To estimate cost savings we need to find out how much your utility company charges you per kilowatt-hour. This should be displayed on your bill. Alternatively, they might detail their rates on their website or an independent body may have aggregated data. Again, these rates will vary widely depending on the mix of generation methods used and how costly it is. For example, in the United States, the average cost for Residential consumers last year was 11.8 cents per kWh. However, consumers in New Jersey were paying an average of 16.24 cents whilst those in Washington were only paying 8.33 cents per kWh.

Again, once you have this figure (or a typical average) you can estimate the potential cost savings from your solar array by multiplying the cost per kilowatt hour by the total amount of kWh of electricity you have estimated you will generate in a year.

Examples

To finish off, let’s look at some examples to see how this all comes together and to also get an idea of differences in different regions. As we’ve already looked at the differences in costs of electricity between New Jersey and Washington, let’s use Trenton and Seattle as examples along with Los Angeles in California. We’ll assume an area of 20m2 for our solar panels and a CO2 cost of 1lbs/kWh for all cases (note that the solar radiation figures used here are approximates).

Trenton, New Jersey

Potential Energy Per Year = 20×3.5x365x0.1 = 2555 kWh/Year

Potential Carbon Footprint Reduction = 2555 lbs/Year

Potential Cost Savings = 2555×0.0833 = $212.84/Year

Seattle, Washington

Potential Energy Per Year = 20×4.7x365x0.1 = 3431 kWh/Year

Potential Carbon Footprint Reduction = 3431 lbs/Year

Potential Cost Savings = 3431×0.1624 = $557.20/Year

Los Angeles, California

Potential Energy Per Year = 20×6.1x365x0.1 = 4453 kWh/Year

Potential Carbon Footprint Reduction = 4453 lbs/Year

Potential Cost Savings = 4453×0.1524 = $678.64/Year

I think these numbers are enough to get across the point that the actual cost savings will vary depending on where you live and this value needs to be weighed against the cost of installation on an individual basis.

Additional Considerations

Whilst these calculations give a good ballpark for the potential savings you could make with solar panels there are other considerations to take into account when planning an installation:

* Cost of installation – get multiple estimates!

* Additional shade (eg surrounding buildings, trees etc.) that might affect your potential power output

* Direction your roof faces and it’s angle

* Up-keep costs – although solar panels are very low maintenance and typically have a lifespan of 25+ years this should be taken into consideration when estimating life-time savings

* Selling back to the grid – if you don’t use all of the electricity you generate, you can usually sell it back to the utility companies which may increase or lower the overall value of the power you generate

About Oliver

Oliver is a keen advocate of renewable energy and the benefits it can have for both the environment and the consumer’s pocket. He writes about how to get the most out of solar power for Solar Contact, a US website aimed at helping consumers find solar installers.

How Would We Survive Without Electricity?

A service we all take for granted, many of us switch on the lights in our home without sparing a thought for the electricity we are using. In fact, many of us are largely unaware of how electricity is generated and could not imagine a life without it.

Yet, a time without electricity did exist and whilst its invention remains largely unknown, the names of Thomas Edison and Luigi Galvani are now synonymous with it. For those of us who have grown up alongside this convenient service, imagining a time where lights don’t turn on at the flick of a switch is something hard to contemplate – but does that mean we couldn’t survive without electricity?

Homes without power

Of course, whilst not having electricity would be a huge shock we would soon adapt and find ways to cope with the change. Whether this involved reverting back to former sources of light (such as traditional candles) or creating new ways to power our electrical devices (such as through solar power) the end result would still be survival.

In truth, the idea that we may one day be left without electricity is somewhat far-fetched. It is reasonable to assume that the source of our electricity might change but electrical power of some description would still exist.

What are the alternatives?

For those wondering what I mean by this, the development of solar power could be the energy source of the future. The Government is already subsidising solar panels to homes willing to try the technology and a widespread roll-out of solar panels is something many people see as inevitable.

Solar panels would harness power for our electrical goods in a more environmentally friendly manner as it is a renewable source of energy and does not cause unnecessary damage to the environment. Traditional electricity, on the other hand, relies on the consumption of fossil fuels and emits harmful carbon dioxide into the atmosphere.

Solar energy facts

Solar energy offers households a number of benefits – including reduced energy bills and lower carbon emissions. For those interested in what this power source has to offer, here are some facts you should know:

- Solar energy is responsible for 20% of energy use.

- Consumers who fit solar panels to their home can save as much as 800 pounds (about C$1000) a year through Feed-in-Tariffs (FITs) which were introduced in April 2010 to offer a rebate on energy costs to these customers. Regardless of what source you use for your household electricity, those interested in reducing their bills can compare different tariffs and electricity prices to find the best deal.

- High profile scientists such as Albert Einstein were familiar with the concept of solar power. In fact, Einstein won a Noble Prize for his work with photovoltaic cells back in 1921

Fern Rodgers is an environmental preservationist and frequent blogger. Responsible for researching the benefits and uses of renewable energy sources, Fern offers regular advice on how to make your home more efficient. She also evaluates electricity prices and tariffs to find the best deals for consumers.

Geothermal Energy The Heat Of The Earth

Geothermal energy is energy obtained by tapping the heat of the earth itself, usually from kilometers deep into the Earth’s crust. It is expensive to build a power station but operating costs are low resulting in low energy costs for suitable sites. Ultimately, this energy derives from heat in the Earth’s core.

Three types of power plants are used to generate power from geothermal energy: dry steam, flash, and binary. Dry steam plants take steam out of fractures in the ground and use it to directly drive a turbine that spins a generator. Flash plants take hot water, usually at temperatures over 200°C, out of the ground, and allows it to boil as it rises to the surface then separates the steam phase in steam/water separators and then runs the steam through a turbine. In binary plants, the hot water flows through heat exchangers, boiling an organic fluid that spins the turbine. The condensed steam and remaining geothermal fluid from all three types of plants are injected back into the hot rock to pick up more heat.

The geothermal energy from the core of the Earth is closer to the surface in some areas than in others. Where hot underground steam or water can be tapped and brought to the surface it may be used to generate electricity. Such geothermal power sources exist in certain geologically unstable parts of the world such as Chile, Iceland, New Zealand, United States, the Philippines and Italy. The two most prominent areas for this in the United States are in the Yellowstone basin and in northern California. Iceland produced 170 MW geothermal power and heated 86% of all houses in the year 2000 through geothermal energy. Some 8000 MW of capacity is operational in total.

There is also the potential to generate geothermal energy from hot dry rocks. Holes at least 3 km deep are drilled into the earth. Some of these holes pump water into the earth, while other holes pump hot water out. The heat resource consists of hot underground radiogenic granite rocks, which heat up when there is enough sediment between the rock and the earths surface. Several companies in Australia are exploring this technology.

Geothermal Energy Prospects

The Geysers, is a geothermal power field located 72 miles (116 km) north of San Francisco, California. It is the largest geothermal development in the world outputting over 750 MW.

By the end of 2005 worldwide use of geothermal energy for electricity had reached 9.3 GWs, with an additional 28 GW used directly for heating. If heat recovered by ground source heat pumps is included, the non-electric use of geothermal energy is estimated at more than 100 GWt (gigawatts of thermal power) and is used commercially in over 70 countries. During 2005 contracts were placed for an additional 0.5 GW of capacity in the United States, while there were also plants under construction in 11 other countries

Wind Power An Alternative Energy

A wind turbine needs air, lots of it to turn the blades. A modern wind turbine ranges from 600 KW to 5 MW of rated power, although for commercial use the output range is typically 1.5-3 MW.

Because wind speed is not constant, a wind farm’s annual energy production is never as much as the sum of the generator nameplate ratings multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. Typical capacity factors are 20-40%, with values at the upper end of the range in particularly favorable sites. For example, a 1 megawatt turbine with a capacity factor of 35% will not produce 8,760 megawatt-hours in a year, but only 0.35x24x365 = 3,066 MWh, averaging to 0.35 MW. Online data is available for some locations and the capacity factor can be calculated from the yearly output.

Globally, the long-term technical potential of wind energy is believed to be five times total current global energy production, or 40 times current electricity demand. This could require large amounts of land to be used for wind turbines, particularly in areas of higher wind resources. Offshore resources experience mean wind speeds of ~90% greater than that of land, so offshore resources could contribute substantially more energy. This number could also increase with higher altitude ground-based or airborne wind turbines.

Wind power is renewable and produces no greenhouse gases during operation, such as carbon dioxide and methane.

Wind Power Market

At the end of 2008, worldwide wind farm capacity was 120,791 megawatts (MW), representing an increase of 28.8 percent during the year, and wind power produced some 1.3% of global electricity consumption. Wind power accounts for approximately 19% of electricity use in Denmark, 9% in Spain and Portugal, and 6% in Germany and the Republic of Ireland. The United States is an important growth area and installed U.S. wind power capacity reached 25,170 MW at the end of 2008.

Horse Hollow Wind Energy Center, in Texas, is one of the world’s largest wind farm at 735.5 MW capacity. It consists of 291 GE Energy 1.5 MW wind turbines and 130 Siemens 2.3 MW wind turbines. A proposed 4,000 MW facility, called the Pampa Wind Project, is to be located near Pampa, Texas.

In the UK, a licence to build the world’s largest offshore windfarm, in the Thames estuary, has been granted. The London Array Windfarm, 20 km off Kent and Essex, should eventually consist of 341 turbines, occupying an area of 230 km². This is a £1.5 billion, 1,000 megawatt project, which will power one-third of London homes. The windfarm will produce an amount of energy that, if generated by conventional means, would result in 1.9 million tonnes of carbon dioxide emissions every year. It could also make up to 10% of the Government’s 2010 renewables target.

Wind Farms

Wind power is one of the most environmentally friendly sources of renewable energy

A wind farm, when installed on agricultural land, has one of the lowest environmental impacts of all energy sources:

* It occupies less land area per kilowatt-hour (kWh) of electricity generated than any other energy conversion system, apart from rooftop solar energy, and is compatible with grazing and crops.
* It generates the energy used in its construction in just 3 months of operation, yet its operational lifetime is 20 to 25 years.
* Greenhouse gas emissions and air pollution produced by its construction are low and declining. There are no emissions or pollution produced by its operation.
* In substituting for base-load coal power, wind power produces a net decrease in greenhouse gas emissions and air pollution, and a net increase in biodiversity.
* Modern wind turbines are almost silent and rotate so slowly (in terms of revolutions per minute) that they are rarely a hazard to birds.

Studies of birds and offshore wind farms in Europe have found that there are very few bird collisions. Several offshore wind sites in Europe have been in areas heavily used by seabirds. Improvements in wind turbine design, including a much slower rate of rotation of the blades and a smooth tower base instead of perchable lattice towers, have helped reduce bird mortality at wind farms around the world. However older smaller wind turbines may be hazardous to flying birds. Birds are severely impacted by fossil fuel energy; examples include birds dying from exposure to oil spills, habitat loss from acid rain and mountaintop removal coal mining, and mercury poisoning.

Wind Power A Viable Energy

Although initially is much cheaper to get hooked up to the local power company than it is to set up and hook into your own wind power system, in the long run you saves money by utilizing the wind for your energy needs while also becoming more independent. Not receiving an electric bill while enjoying the vantages of the modern electrically driven society is a marvelous feeling.

Electric bills and fuel bills are rising steadily, but the cost of wind power energy is low, and the cost of installing and hooking up a wind turbine is steadily coming down as demand rises and more commercial success is realized by various companies producing the turbines and researching technologies to make them ever more efficient.

Additionally, people are moving away from the conventional electric grids and the fossil fuels for personal reasons including desire for greater independence, the desire to live remotely or rurally without having to “go primitive’, governmental concerns such as fears of terrorist strikes on oil fields or power grids, and or concerns about the environment.

Once more, this need to get away from the conventional energy sources is the same one that drives people to look for the power of the wind for their energy need, giving added business opportunities to profit from wind turbine production and maintenance, which drives their costs down for the consumers.

In many provinces in Canada and states in the US where homeowners are allowed to sell their surplus energy back to the power company under what are called “net metering laws”. The rates that they are being paid by the local power companies for this energy are standard retail rates, put differently, the users are actually benefiting from their own energy production.

Some federal lawmakers are pushing to get the federal government to mandate these tax breaks and other wind power incentives. Japan and Germany already have national incentive programs in place.