How Much Solar Power? Determining How Many Watts Your House Needs

Once you've decided to add a system of solar photovoltaic power panels to your house or business or determined that it's time to expand an existing system, the next question is: how much wattage do I need?

To find this out, you will need to know how much power you consume (or how much you plan to consume, for new buildings or for additions that will require lots of power - like a woodworking shop or a hot tub) and how much sunlight you receive throughout the year.

\"Energy Efficiency\"

Assuming that you've been at your location for at least a year (so that you have a good feel for your electric needs for each season), take each electricity bill and write down the number of kilowatt-hours (kw-h) that were billed and the number of days in the billing cycle. Then, divide the number of kw-h by the number of billing days to get the average kw-h per day. To make things simpler, some people just assume 30 days for each billing cycle (and not all power companies report the billing days). That's how many kw-h your system will need to generate each day to meet your power needs. Once you've done this for the entire year's worth of bills, you'll know both your average daily consumption and your peak consumption. You may choose to size your system based on either value. If you use the average value (and assuming your power company allows you to sell power back to them, you should definitely check on this first!), then some days you'll make extra power and sell it back to the power company and some days you'll be buying power, but over the course of a year, your net electric bill should be close to

Now, to get the wattage of solar panels that you need, you'll need to know how many hours of direct sunlight that your system will receive. If you've been at your location for several years already, you might have a good idea how many hours of direct sunlight your building receives, either seasonally or on average throughout the year. One way to determine how many hours of sunlight you receive is to take observations several times a day as to whether the portion of your roof where the solar panels are to be installed is sunlit. If you do this every day for a year, you'll have a good idea of how many hours of sunlight your solar panel will receive on a seasonal basis. There are a few problems with this approach: it's very time consuming as it requires you to take measurements throughout the day nearly every day; there will be some days when you just can't take the measurements (you're out of town, working and cannot get to the house to observe the roof, clouds are obscuring the sun, etc.); and, unless you have a solar panel system that tracks the sun, the number of hours of sunlight your roof receives is not the same as the hours of direct sunlight, since much of that light will probably not be coming in at right angles to your roof throughout the year.

Another way to estimate the number of hours of direct sunlight you receive is to assume a value or to use a rule-of-thumb. Often, 5 hours direct sunlight on average throughout the year is assumed. Although this is a fairly common assumption, you might end up disappointed if your solar system generates less power than you anticipated because you get fewer average hours of sunlight than this.

A third method is to look up an average regional value. The Florida Solar Energy Center presented a study in August 2004 at the ACEEE 2004 Summer Study on Energy Efficiency in Buildings titled "Geographic Variation in Potential of Rooftop Residential Photovoltaic Electric Power Production in the United States." This study simulated the power generation of a 2 kilowatt (kw) photovoltaic rooftop system for 236 locations throughout the US. Depending on the location, they found that this 2 kw rooftop system would generate between 5 and 8.5 kw-h per day on average throughout the year.

Using the rule-of-thumb, a 2-kw system receiving direct sunlight for 5 hours per day would expect to generate 10 kw-h per day on average throughout the year. From the Florida study, the same system would be expected to generate only 5 - 8.5 kw-h per day throughout the year.

How you proceed depends on your goals. If your goals are to offset your electricity cost, then any of the approaches will provide an estimate of the number of hours of direct sunlight that you receive. However, if your goal is to become energy independent, then using the results of the Florida simulation would provide a more conservative value that would be more likely to provide a system sized for your needs. Take the results of the simulation and a few of your own observations (whether you have a lot of tall evergreen trees on the south side of your house that block a majority of the winter sun, etc.) and you should be able to estimate the number of hours of direct sunlight that you receive.

For example, if you've decided to use the average power consumption value and you use 600 kw-h per month and your billing company doesn't report the number of days per billing cycle (assume 30 days per month), then you consume 20 kw-h per day of electricity (600 kw-h divided by 30 days per month). Using the Florida simulation data and assuming you live in Western Kentucky, you receive approximately 3.5 hours of direct sunlight per day (from the graphic, estimate a value of 7.0 kw-h divided by 2 kw - the study is based on a 2 kw system). Then, your system would need to be sized for approximately 5,700 watts.

. If you use the peak number, then you should be selling power back to the power company almost every day, but your system will cost more than if you sized the system based on the average power consumption.

How Much Solar Power? Determining How Many Watts Your House Needs

Daniel Peplinski

[http://www.Earthsolarpanel.com/]

http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-380-04

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Fundraising Efficiency

Fundraising is time consuming and sometimes expensive. Let us look at ways to make it more efficient.

The number of resources consumed to achieve success measures the efficiency of an activity. Since fundraising is about money, it is appropriate to translate all of the resources into dollars (labor hours, opportunity loss, supplies, advertising and marketing, etc.). Using dollars makes it easy to create a ratio of dollars raised to dollars spent.

Efficiency

So what is a reasonable ratio? We encourage our clients to strive to have 82% of every dollar raised spent on the mission (only 18% is spent on raising funds). Other organizations, such as the Better Business Bureau use other guidelines.

Let us assume that a fundraising event costs ,000 to put on (venue rental, staff time, marketing, food, entertainment, etc.). Let us assume the attendees give ,000 (entrance fees, donations, purchases if there is something to buy or bid on, etc.). The arithmetic looks like this:

Income ,000

Cost ,000

Net ,000

Efficiency ,000/,000 = 28%

Instead of having 82% of the funds for the mission this event provides only 28% of its funds for the mission. It would be better stewardship for the donors to stay home and write a check for the same amount they would have spent.

This is only one activity in an entire year of fundraising. However, achieving the annual goal of 82% efficiency means that the organization must raise an additional ,000 without any expenses (staff time, newsletter, etc.). For your organization, how realistic is that? The alternative is to have the cost of raising the rest of the funds for the year significantly above 82%. While it is possible, for most organizations it is unlikely. The largest and best fundraising organizations find it difficult to keep the mission dollars above 90%.

When a major donor underwrites the event costs, the results are more favorable but still short of the desired goal.

Income ,000 + ,000 (major donor underwriting of event costs)

Total Income ,000

Cost $ 5,000

Net $ 7,000

Efficiency $ 7,000/,000 = 58%

Clearly, the major donor helped to improve the ratio. Of course, this simple example assumes that no costs were incurred to attract the major donor's support. Even with the support of the major donor, it makes reaching the organizational efficiency goal difficult.

Of course, the unmentioned alternative is to significantly increase the event income. If the event generates more than ,000 it will achieve the efficiency goal.

Here is a different way to look at efficiency. Let us assume the agency has a 0,000 annual budget. Holding an event that raises ,000 produces only 1% of the annual need. It would take 100 events to fund the organization. If the event produces ,000 it is providing less than 5% of the needed income or more than 20 similar event will be necessary to fund the mission.

Many organizations hold three or more events each year but are unable to satisfy either efficiency test. Is now a good time to weed out some of the inefficiency and focus your fundraising on the most productive opportunities?

The goal of achieving 82% is achievable. It requires careful planning, being intentional about efficiency, and ensuring that events achieve the necessary donor participation to produce sufficient income.

Next Step:

Work with the board to establish an efficiency goal for your fundraising

Measure the efficiency of all of the fundraising activities (year-end appeal, special events, newsletters, etc.)

Determine which ones can be modified to reach your efficiency goal and abandon the rest

Fundraising is very competitive. The level of competition is going to be increasing for the next several years. At the same time, the donors are becoming more aware of issues like fundraising efficiency. In addition, foundations and rating agencies are being force to be more attentive to fundraising efficiency.

Over the past few years donor attrition has been high for many nonprofits. To our knowledge no one has studied what percentage of the donors have been lost due to dissatisfaction with the fundraising efficiency, but it is reasonable to assume that number will increase as donors become more concerned about fundraising efficiency.

When a donor becomes frustrated by inefficiency, he or she has two choices. One is to circumvent the inefficient process and write the check directly to the agency. The other is to walk away from the agency. How many of your donors are so passionate about the mission that they will take the time to circumvent the inefficient process?

Organizational sustainability is dependent on having a sustainable funding stream. It is very difficult to have a sustainable funding stream without having an efficient fundraising process.

If you had help making your fundraising more efficient, would the increased efficiency more than pay for the cost of the help?

Fundraising Efficiency

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Disadvantages of Alternative Energy

Alternative energy would seem like a good choice for new home builders and people who are in the market to buy a new automobile. There are disadvantages of alternative energy that realistically need to be considered.

One of the biggest disadvantages of alternative energy is that it cannot be stored like coal and natural gas can. Storage is a huge issue because using alternative energy puts us at the whim of Mother Nature. If there is no wind for a week, relying on wind power becomes a problem. If you are too far north, solar panels will only produce sufficient energy when the Northern Hemisphere of the planet is tilted towards the sun and so on.

Energy

Other sources of alternative energy are being studied as well to power not only our homes but our vehicles as well. Hybrid cars have been on the market for a while. They use the same idea as an electric car only they don't need to be plugged in to recharge. They use their braking system to regenerate power and they still have all of the engine power of a gasoline engine. New technologies to produce a fuel cell vehicle are currently underway along with a hydro-powered hybrid using hydrogen.

Another of the disadvantages of alternative energy is that it can be expensive to implement into our already set up infrastructure. Most of the alternative energy resources available today require a different type of wiring system than what we currently have in place. This could cause the transformation to alternative energy sources to be delayed until we have depleted the remaining amounts of fossil fuels found on our Earth today.

Fossil fuels are less expensive right now than alternative energy due to the amount of changes that have to be made to adapt a alternative energy plan. This proves to be another one of the disadvantages of alternative energy. Fossil fuels are readily available and easy to use. They can be transported to almost any location for use. Power plants are already set up for burning fossil fuels like coal and this makes the whole process less expensive than transforming to alternative energy.

The advantages of using alternative energy will be realized when people are forced to make the change if for example, we deplete all of our fossil fuels or the cost of use simply become prohibitive. The disadvantages will slowly fade away as more and more people use alternative energy as their source of power.

Disadvantages of Alternative Energy

Read more about renewable energy at SolarCompanies.com

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