How Much Solar Energy Do I Need?

How Much Do I Need? An Answer To The Most Common Question in Solar Power

We have the pleasure of working with hundreds of people every day that want to reduce their energy bills, go green and jump on the solar power bandwagon.  And the question we see over and over again is: Just how much do I need and what will it cost?  We’ll tackle that question here and show you how we calculate system size and cost.  We have simple solar calculators that can do this on our website but so many people have asked how this is actually calculated we thought we’d give a quick solar design lesson.

Start With the Consumption

We spoke to someone just yesterday that wanted solar panels on a 8’x22’ trailer.  We asked him what his usage was, and his answer floored us.  He was using 7000 kilowatt-hours per month, about 6 times the average household consumption.  As it turns out the trailer was an enormous ice maker.  This illustrates that homes and buildings of all sizes vary widely in their energy consumption.  A 1200 square foot house in Florida might use 3 or 4 times what a similar house in Missouri uses because of air conditioning and different types of HVAC units.

 

So when planning a solar system, you have to know what you use.  The easiest way to do this is to simply look at your power bill.  You’ll want to look at the “kw-hrs” number, which is short for kilowatt hours.  A kilowatt hour is 1000 watts running for 1 hour.  This number will determine just how many watts are required to almost completely eliminate your power bill.

Factor in Your Location

We also have to account for where you live.  We deal with many customers that live in extremely sunny locations like the southeast and the Caribbean.  But we’ll also get calls from the Northern Territories in Canada where sun exposure is far less.  A 10,000 watt system in Atlanta will generate much more power in a year than a 10,000 watt system in Alaska.   The same is true of locations that are geographically much closer to each other.  For instance Spokane, Washington has almost twice the sun exposure of Seattle, Washington.

To account for sun exposure, weather patterns, and latitude, we use a number called ‘full sun hours’.  This doesn’t mean the hours that the sun is in the sky, but is a weighted number that helps us determine how a solar panel system will typically perform in a given area.  Most of the US has a number between 3 and 5.  Some areas close to the equator have a number closer to 7.  The solar exposure map is below:

Now Calculate Wattage Produced

So now we have the basic information that can help us get a rough idea of what a system will look like.  Here’s a simple formula that will get you close to your number:

Monthly Consumption (kw-hrs)                           = Rough solar kilowatts

(30 x Sun-hours for your area x .80 to account for efficiencies)

 

Now an installer will tell you that does not account for things like shading, angle of solar panels, etc., and they would be right.  But for rough calculation this will suffice.

Now Calculate a Rough Installed Cost

We have determined a general system size, let’s crunch some numbers to see what this will cost.  Installed solar costs vary widely across the country, but a good rule of thumb these days is equipment and installation for a standard grid tie, roof mount system will cost between $4 and $5 per watt.  So if we take the average of that number and the result of the previous calculation:

Rough solar kilowatts x 1000 x $4.50/watt = Rough solar cost estimate.

Now the installed cost per watt can vary for any number of reasons:

·         Difficult installation

·         Higher labor rates

·         Inadequate roof space

·         Remote location

·         Travel time for installers

·         Special equipment requirements

·         Special building code requirements

But, for most people, this will give them a good idea of what solar power will cost for grid tied systems.  And of course this does not account for incentives at the local, state and federal level.  In many areas where installation is more expensive (such as both the East and the West coast) incentives are also higher.

Now you can take on the next important question:  Where am I going to put all these solar panels?

Kriss Bergethon is a solar expert and writer from Colorado, visit his site at Solar Panels for more information.

Navy Leads Nation

Navy Leads Nation Towards the Future of Solar Energy

In between mid-May and early October of this year, many facilities located on the Pearl Harbor Naval Base had solar hot water systems installed. The final inspection for this large project was held on October 3, 2011 and this particular project is projected to save $200,000 annually because of the changes made. The Department of Defense had made it possible for the Navy to pursue this project because it was agreed upon by the Energy Conservation Investments Program (ECIP) that this would greatly reduce cost and energy consumption. Navy Housing is switching to green technology, why not do the same on the base? There should be no question as to why this makes perfect sense to heat water using solar power.

Last year, during the month of June, the Naval Facilities Engineering Command received $2.2 million through the ECIP for their Pearl Harbor base. Six buildings received these new solar hot water systems, five of which are enlisted and officer quarters while the last facility is a gym. 6,120 sq. ft. of solar panels were installed by the Niking Corporation, which single handedly made this the largest project of this sort. The Navy expects the amount of paneling to power close to 440 homes which are located on the base. This number is significantly large considering that Hawaii, as a state, is not fossil fuel rich like some other states in the country. This amount of panels is capable of heating up 14,000 gallons of water a day and this project took about five months to complete.

On top of the six buildings that received new hot water systems, the contract allowed for a 100-kilowatt photovoltaic system to be added to one of the biggest and most energy consuming buildings located on the base. This thin film that has been installed will reduce this particular buildings demand for power on the grid by more than 150,000 kilowatt hours per year. It has been estimated that it will take about 11 years for the Department of Defense to receive all of its money back for the funding of this project, but again the estimated annual savings will be about $200,000.

In the year of 2009, the Secretary of the Navy, Ray Mabus, had mapped out and suggested five major energy goals that will improve security and efficiency. In turn, this will ultimately increase the base’s independence of energy and be a milestone for the nation to rethink and go this same route. Another astonishing figure to look at is: because of the installation of these solar panels and photovoltaic film, over a 30 year span it is estimated that it will reduce the carbon dioxide emissions on this base by about 4,600 tons! That number is equivalent to planting 1,300 new trees, or removing about 1,000 cars that damage the ozone daily. This energy goal that has been presented by Secretary Mabus is expected to be carried out and completed by the year 2020 and the Department of the Navy will be responsible for producing about half of the on shore based energy requirements.

Clearly the Naval Base in Hawaii has taken the proper steps in leading the rest of our nation to be proactive in going green and becoming more sustainable as a country. We have the technology, we just need to follow through with the plans and get the word out about how much better for the world solar power is. This sort of sustainable living solution is not only available to the military and government; people can also use solar power in their homes and small businesses. Hopefully, more people will follow suite and the government will continue to back these types of projects.

It is important to compare gas and electricity providers in order to find affordable green energy suppliers. Switching suppliers will help you lower your utility bills and provides funding to gas and electricity providers that are focused on sustainability.

Solar Panel Costs

Falling Solar Panel Costs Are Great For Buyers, Bad for Producers

A recent industry analysis projects the amount of solar power installed to grow to 15.5 percent per year, but revenues are to stay flat until 2016. Lux Research provided the report. A report from Navigant Consulting discovered that the price of solar panels is down almost 20 percent as of August 2011. The information derived from these two reports show that the consumer is poised to benefit from the price reduction while manufacturers can expect an almost flat profit margin for the next few years.

Manufacturers of solar panels are in a constant price competition. This literally boils down to shaving price per watt by pennies in order to beat out competitors. The reports mean shrinking profit margins with concerns over demand for panels staying strong. Manufacturing capacity for solar hardware is increasing, but the unknown factor is if there will be enough buyers to consume the increased output.

Consumers stand to benefit from the softening in prices as it translates into more solar capacity for the same amount. The lower prices give rise to the idea that solar leasing, an alternative to purchasing panels outright, may gain more traction. However, lower prices go beyond that. A solar industry analyst feels there is an ultimate benefit in the falling prices. It makes solar power leasing viable in states that have been written off in the past.

Solar power leasing is designed to provide an alternative to purchasing a solar panel array upfront. Instead of buying the solar panels, consumers pay a monthly fee that reduces their electric bill. In a lease situation, a predetermined fee is set for 20 years. The consumer can also participate in a power purchase arrangement; the consumer buys power from the solar panels. A purchase arrangement is cheaper than buying from traditional grid suppliers.

A consumer can expect to pay $30,000 for the purchase and installation of a complete rooftop solar power array. A 30 percent federal tax rebate and possible state incentives serve to lower the cost. The solar panels make up less than half of the total price, with the rest of the cost going towards labor and necessary hardware. Consumers are going to see little, if any, benefit in the price competition from producers. The price change is going to be seen mainly by installers and solar power lease companies.

It is thought that solar power has the potential to reach what is known as "grid parity," wherein the cost of solar power is cheaper than traditional grid suppliers. This theory can become reality if the price of solar panels continues their precipitous price drops.

Lux Research projects that grid parity will reach commercial solar panel installations first, and that ten countries will reach that point by 2016. For the time being, state subsidies and the cost of retail power, dependent primarily on crude oil prices and coal spot price, are key to allowing solar power to undercut grid power. Anticipated increases in the cost of wholesale and retail electricity will serve to increase demand for solar power.

Kriss Bergethon is a solar expert and writer from Colorado.  Visit his site at Solar Panels for more information.