Last weekend, I spent some time at the Wichita Area Builders Association Home Show at Century II. I had been invited by Nick King of King’s Solar Wind Plumbing to help out and answer questions about Home Energy Audits. I got to visit with a lot of interesting people coming through the Home Show. I also got to listen to Nick, Mark, Lee, Tom, Nelson, and Ellsworth about Solar Power for residential and other uses.
I went in with a lot of questions and got the answers. For this post I decided to take what I learned and put it in a Q/A format for the readers of the blog. So pull up a chair and read through the questions and the answers. Then think about the potential of adding solar on your home or business.
Q: What type of energy do Solar Panels provide?
A: Some panels use the heat from the sun to warm air. This can be circulated into the house; it can be stored in a thermal mass. This would be a Solar Thermal type panel.
Some panels use the heat from the sun to heat water. The water can provide hydronic (water based) heat or hot water or both. This would also be a Solar Thermal type panel.
Some panels use the heat from the sun to generate electricity. This would be a photovoltaic (PV) solar panel.
Q: How long does a Solar Panel last?
A: Many existing solar panels were installed 30 years ago or more. These panels provided hot water or hot air. Many are still in use and are expected to continue with minimal maintenance for years to come. There are no moving parts on a solar panel.
Q: There are Hail Storms in Kansas! What happens to my expensive solar system when it gets hit by hail.
A: The solar panels are made of tempered glass. They are rated and tested for a one inch hail stone. A couple of years ago, a commercial solar array in Texas was hit with a hail storm and stones the size of tennis balls. A total of 600 panels on this system had only 2 panels damaged.
Q: How do you take care of the batteries, so you don’t have to pay the electric utility?
A: Actually, you want to stay hooked up the to electric utility so you can use them for your battery. That means no replacements, maintenance expense or other cost. Kansas Law now requires a 1:1 exchange. When you generate more than you use, the two-way meter, sends it out to your electric utility to deliver to someone else. When you need one, it trades one back. The planning key is to know what time period your utility uses. Some run the trades for a month and then each month starts with a clean slate. Some Utility Companies use a different length period, which could be as long one year. Other states may have very different requirements, so check first!
Q: Would my home be worth considering solar?
A: It depends on the solar conditions on your property. A house with a small yard is best set up for solar by having a south sloping roof. The sun lower in the winter, a south slope on the roof, helps maximize your solar generation. The other solar condition to consider is shade. Some parts of your roof may be shaded by parts of your house or by nearby trees.
Q: Do you put one big solar panel or a lot of little ones on the roof?
A: Most residential PV panels are 39×65 inches. A typical installation may be 10 to 30+ panels. The actual number depends on your utility usage and your goals.
Q: How do you figure out how many panels to put on a house?
A: How much electricity do you use? Then how much of the existing electricity that you have been paying for, can you eliminate through efficiency improvements? In this way, you can buy a smaller more efficient system.
Q: What type of improvements that are energy efficient do you recommend?
A: Efficient Energy Star appliances are a good place to start. You can look at your refrigerator, deep freeze, the garage refrigerator, and others. You can look at your vampire loads and look at ways to drop these ineffective or wasteful uses. The larger savings may be in having your home ready for solar by installing enough insulation or sealing up all the air leaks, and choosing the HVAC system that best matches your needs to efficiency.
Q: What is the best way to make these determinations about the existing efficiencies of my home?
A: We recommend a comprehensive Home Energy Audit! It should include a Blower Door Test with an Infrared Camera testing for air infiltration. Your auditor should computer model the energy usage on your home as it stands now, and demonstrate the savings of various improvements.
This video from the Department of Energy describes a good Home Energy Audit.
Q: How do I find a good energy auditor?
A: You can check with your Electric Utility Company. You can check with the Kansas Energy Office. You can also check in Kansas and nationally for an auditor with RESNET. If you don’t live in Kansas you can check with your state’s Energy Office.
Q: I am renting right now and will start building a new home in about 6 months. How do I make sure my new home is ready for solar?
A: To start with you should begin planning your home to meet Energy Star Standards. This would require an Independent Third Party to first review the plans for the home and then to inspect at various times during construction to verify the plans are being followed. As of January 2012, no city, county or other code enforcement authority, in Kansas, has adopted any Energy Code. If they do in the future, a code requirement for energy would be a minimum requirement, and many of the better builders prefer to build a house that is better than the code minimums.
You can exceed Energy Star Standards to build a new home by having your contractor meet the requirements of the Department of Energy’s ‘Builder’s Challenge Program’!
Q: What if my roof is not the best candidate to mount solar panels on the roof?
A: You can do a ground mounted system. It depends on having ground around your home that is not shaded from trees or buildings. You can also calculate the amount of reduction in Solar Efficiency the shading causes, then you can determine if you wish to go ahead.
Q: How many volts does each panel generate?
A: Solar panels are becoming standardized by most manufacturers. A 39×65 inch panel, usually will provide 235 watts of power. You buy electricity from your Electric Utility by the Kilowatt Hour. That is 1000 watts over 1 hour. That means that 5 panels will generate about 1 Kilowatt Hour of electricity each hour the sun shines at peak value.
Q: Why do you say about? Isn’t it exact?
A: The electricity generated by the solar panel is direct current. It must be changed, with an inverter, to alternating current to match the electric set up in your home. The efficiency of the inverter can vary by manufacturer. The efficiency can be as low as 75% or as efficient as 92%. I use a 92% efficient inverter.
Q: Why do you say peak value?
A: The solar panel generates the maximum power when everything works together. At 9:30 the sun shines on the panel more directly then when it first started shining on the panel and thus the panel generates more electricity.
Peak Value or Power is also affected by clouds and shade from trees or buildings. Ten years after you install your solar panels, the neighbor’s trees will grow and perhaps are casting a shadow on your panel. This will change over time.
Q: If a tree is shading my panel part of the day, how much would that really help in the winter after the leaves are gone?
A: The branches would average about 50% of the summer shade value in the winter. The exact amount would depend on the type of tree, how far away it is, and how large it is.
Q; What is ‘Net Zero’ ?
A: ‘Net Zero’ is a term that shows your home takes no energy from the utility grid over a period of time, usually a year. It allows you to trade KWH back and forth, with the end result of no net purchases.
‘Net Zero’ does not mean you are not hooked up to the grid. That would be termed ‘Off Grid’.
Planning for your home to be ‘Off Grid’ or to become ‘Net Zero’ is the same process with quite different approaches, efficiency parameters, costs and results. ‘Off Grid is an approach that would appeal to a much smaller number of families than ‘Net Zero’. ‘Net Zero’ is much more affordable at this time than ‘Off Grid’!
Q: Do you have to have an All Electric home to achieve a “Net Zero” status?
A: No, you can calculate how much extra electricity that your panels produce over your electric needs to offset the natural gas or propane used.
In Kansas, you only get credit for the number of KWH that you trade in and then take back out. Generating more KWH and sending to the grid is a nice thing; but to do this your array is more expensive and thus you have a ‘green payoff’ instead of a ‘cash payoff’!
Q: Where are solar panels made? Overseas, like everything else?
A: You can buy Solar Panels made overseas. You can also buy panels made in New Mexico or California. Those made here in the US are of the same quality as the imports and the same of better cost. Also, the energy used to transport them to your home is much less, because they are closer to start with.
Q: What do I get from adding Solar to my home?
A: Take your pick! Save Money! Go Green! Cut the carbon footprint? It is the right thing to do!
What you get is up to you. You may choose to add Solar for one of these or another reason. The value is for you to appreciate.
For an additional view on Solar, here is a Blog post from Martin Holladay, blogging as ‘The Energy Nerd’.