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Category:
Published: February 2008
Solar Hot Water, some basics to work with...
Here is some information that may help you decide if Solar Domestic Hot Water is right for you.
Well start by using the abbreviation SDHW instead of typing it out every time (saves my fingertips from blisters). SDHW is the use of the suns energy to generate hot water for your sinks, showers, etc.
A properly sized and installed SDHW system can reduce your hot water costs by an average of 50-80%, and pay for itself in as little as 5 years, maybe even faster as utility prices continue to rise.
A SDHW system consists of a few basic parts:
- The collector panel, either a flat panel collector like we all became familiar with back in the 70s, or the newer and nifty evacuated tube collectors which are a series of glass tubes with a metal panel inside that heats up with the suns energy.
- The pump system, which moves the collector fluid through the system.
- The storage tank that hopefully keeps the water the sun has so graciously heated for us hot as long as possible.
- A backup heater.
- The balance of system including pipes, temp sensors, valves and other various bits of technology.
"How does it work?"
It actually is pretty simple. Fluid (usually a 50-50 mix of glycol and water to prevent freezing issues) is pumped through the collectors which are heated by the sun and thus heat the fluid. That hot fluid is moved down to the storage tank by the pump system and flows through a heat exchange coil which transfers the heat to your portable water. These coils are either inside the storage tank or some type of external heat exchanger. This continues to circulate until the system senses that your stored water is hot enough or until the sun goes down. The water in the storage tank then flows through your back up water heater because, lets face it, the sun does not always cooperate. This preheated water then reduces how hard your backup heater has to work. A SDHW system can be easily tied to your existing hot water system, whether a regular hot water tank, or on-demand boiler, etc.
TA DA!! Free hot water.
The most important consideration, as with all solar collectors, is sun exposure. If where you want to put the collectors is shaded by trees, hills or other buildings, it is NOT going to work. The direction a collector faces is also very important. Here in the Northeast we are north of the equator, so we need to face the collectors south (because that is where the sun is) to collect as much direct sun as possible. We can work with southwest or southeast, but east and west are not good, and north is completely useless.
A collector can be mounted on the roof or on the ground. The pump system can either be powered by your regular electric system or by a small solar panel, which would assure operation even during power failures. To size the tank, we usually double the size of your current tank. If you have a 40-gallon tank now, we would most likely put in an 80-gallon solar storage tank. In general, you want to try and heat as much water as possible during the day so you have hot water the next morning. The number of collector panels depends on how big the storage tank is. One of the biggest decisions is which collector to use. The flat panels and evacuated tube systems are pretty close in efficiency over the course of a year. Flat panel collectors are considerably cheaper, but tubes are easier to install, repair, and add on to I also think that they are better-looking. We can help you decide which would be best for you.
Currently, the cost of a SDHW system for the average household runs between $5000 and $7000 (including installation), depending upon the difficulty of installation and what collectors you need.
Solar Domestic Hot Water is one of the most cost-effective renewable energy systems the average homeowner can afford and feel good about. They look pretty cool, too.
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