What Is Solar Hot Water Energy?
Large solar hot water system: Image courtesy of Wikipedia
When was the last time you really thought about your hot water tank?
Chances are, it’s been awhile. But, stop just a minute and consider this: right now, you’re paying money, and using a lot of energy, to keep those 40 or 60 (or even 80) gallons of water piping hot for whenever you need it.
And, you’re paying for that energy 24 hours per day, 7 days per week.
According to Home Power Magazine, hot water is the second largest energy hog in our homes. And, we spend an average of $3,600 over a tank’s 7 year lifespan heating all that water.
Now, all of us love hot water. There’s nothing better than a hot shower on a cold day. But, keeping all that water on standby like we do is an enormous waste of energy, and money.
Which is why solar hot water systems are so worthwhile.
What Is Solar Hot Water?
A solar hot water system does one thing: it uses the sun’s energy to heat the hot water you need in your home. Depending on what climate you live in, a solar hot water system can replace up to 85% or more of your home’s hot water needs. And many people, especially in Europe, also use that hot water to supplement their home heating by 15-20%.
How Solar Hot Water Systems Work
According to the U.S. Department of Energy, solar hot water systems need two main elements: a solar collector, and a storage tank.
Basically, the collector is attached to the roof of your home. As the water passes through the collector, which is specially designed to absorb the sun’s energy, the water heats up. It’s then pumped (or driven down) to the storage tank, where it sits waiting to be used.
This home is using flat plate collection: Image courtesy Wikipedia
Now, when it comes to solar collectors there are two main options:
- Flat Plate Collectors- These are insulated boxes that have a dark absorbtion plate, and usually attach to copper pipes. These are the most common solar thermal collector.
- Evacuated Tube Collectors- Evacuated tube collectors are rows of transparent glass tubes. Although evacuated tube collectors are extremely efficient, they’re also double the price of flat panel systems. Evacuated tube collectors are usually used in commercial settings.
Now, when it comes to the entire solar hot water system, there are two main kinds: active systems, and passive.
Active Solar Hot Water Systems
Active solar hot water systems use some kind of pump to move the water through the system, and these systems work really well in colder climates, where there is a danger of freezing temperatures.
You can see how it works with this illustration from the U.S. Department of Energy:
Image courtesy USDE
Passive Solar Hot Water Systems
Passive solar systems, also called Thermosyphon systems, rely on the natural movements of hot and cold water to move it through the pipes. Warm water always rises, and cold water always sinks, and this natural movement is taken advantage of with this system.
This illustration, again from the U.S. Department of Energy, illustrates a passive solar hot water system:
Image courtesy of USDE
How Much Does A Solar Hot Water System Cost?
The great news here is that solar hot water systems really pay for themselves over time, and it doesn’t take that long. Home Power Magazine estimates that the return on investment for solar hot water systems is around 15%, which is pretty darn good. It beats the stock market, anyway.
Energy Star estimates that investing in a solar hot water system will cut your hot water bill in half, and save you $190 annually. And if your backup tank is heated with electricity, you’ll save $250 off your energy bill.
And, thanks to the federal tax credits that are available for renewable energy investments, you can recoup your investment even quicker.
The final cost of your system is going to vary depending on where you live, and how much hot water your family uses per day.
But, most systems cost under $5,000. And with the tax credits, it’s even less.
If you’d like to learn what tax credits you’re eligible for, you can visit the Database of State Incentives for Renewables and Efficiency (DSIRE). This great site lists the available tax incentives for renewable energy by each state, so you can easily see what you qualify fore.
DIY Solar Hot Water
Want another piece of good news?
Solar hot water systems are fairly easy to install yourself. Books and kits abound on the Internet, so if you want to save money and have the pride of installing your own renewable energy system, solar hot water would be a great place to start.
Solar hot water systems are also eligible for several state and federal tax breaks for renewable energy. If you’d like to find out how much you’re eligible for, you can visit the Database for State Incentives for Renewables and Efficiency (DSIRE).
A Great Reference
I have read quite a few articles and books on solar hot water and I think this is the best book available. If you’re a handyman with good plumbing skills, or a homeowner wanting to learn more about solar water heating, you’ll want to buy this book.
Solar Water Heating: A Comprehensive Guide to Solar Water and Space Heating Systems (Mother Earth News Wiser Living Series) by Bob Ramlow.