Frequently Asked Questions

How do I know if my site would be a good one for a solar hot water system?

Here are some general criteria:

• Uninterrupted roof area of about 7 feet x 5 feet -- clear of shading
• Southern exposure best, SE or SW will do
• Sun for at least 6 hours per day
• 2-tank system requires space for an additional solar water tank near current tank
• Single tank systems utilize a solar storage tank with internal electric heating element
• Roof must be in good condition, unless you are planning a pole mount, of course

What about solar hot water for hydronic space heating?

Space heating is the biggest energy use in most homes. For a large family or a household with extraordinary hot water use, domestic water heating can also be a large energy use. A single solar water heating system can supply domestic hot water and supplement space heating. However, it is not cost effective to provide most of your space heating with solar in our climate. This is because when you need the most heat is when the solar resource is the least.

If we were to greatly increase the size of the solar collector to provide for space heating needs then there would be too much heat to store in the summer. A heat diversion would be needed to get rid of the excess heat. In addition, for solar heating to supplement hydronic heating, the heating system must operate at a low temperature, with return (from the floor to the boiler) temperatures below 100 degrees. Many heating contractors set the temperatures high so that the floor will respond more quickly to adjustments in the thermostat or to heat loss. These higher temperatures also mean less efficient operation, and less usable input from the solar system. Hybrid solar hot water systems that provide both domestic hot water and space heating are complex and can be costly. When incorporated in new construction, the cost is mitigated somewhat.

So does WSW install such systems? Yes, provided a client has realistic expectations. Kelly's home has extra solar collectors to supplement space heating needs. However, he designed the radiant floor system to run at low temperatures and he and his family are willing to be patient for adjustments in temperature.