Why solar water heating?
Floridians see their electric bills go through the roof during July, August and September and don’t need to be told that air conditioning uses a lot of electricity. At today’s electric rates (including fuel surcharges and utility taxes) of around 14 to 15 cents per kilowatt hour, water heating can easily cost $700 to $1,000 each year for a three to five person household. On Florida's Suncoast, a solar water heater can almost completely eliminate this portion of your electric bill.
Which home energy uses are the most expensive?
The pie chart below shows where the money goes in a typical Florida family’s annual electric bill. The chart is based upon an electric power consumption study by the U.S. Department of Energy’s Lawrence Berkeley National Laboratory. The “typical” Florida household and energy use pattern shown above is based upon these factors:
- A typical Florida home built in 2005 with 2,400 square feet of living area
- 9.5 SEER air conditioner with thermostat set at 81°F during day and 78°F at night
- cold weather thermostat setting of 64°F during day and 68°F at night
- two adults and two children in household
- 80 gallons of hot water per day
- 14 cents per kilowatt-hour electric cost (including fuel surcharge and utility taxes)
Is your hot water use average?
Actually, an active American family of four is probably closer to 100 gallons per average day and just over $1,000 per year at 14 cents per kilowatt-hour.
Hot water facts
Water heating is the second largest energy user in the average home. Only space heating and air conditioning use more energy.
Most water heaters are installed by builders who are more concerned with construction costs than with future utility bills. A conventional electric water heater cost less to install than solar.
The average home water heater lasts 13 years, or less, so don’t wait for your inefficient electric model to go bad…
The savings from replacing it with solar start to pay off immediately!
Oh yes, and there is one other thing we forgot to mention: Using electric power to heat 85 gallons of water from 72°F to 140°F each day for one year sends over three tons of powerplant carbon dioxide and sulfur emissions into Earth’s atmosphere. Yes, really.
Solar energy is clean, safe and free
Naturally, switching to solar water heating means going green in a big way. but you might also be surprised to learn that solar water heating gives you benefits that improve upon conventional electric or gas water heaters:
- More hot water. Most electric water heaters hold enough hot water for about 20 minutes of continuous use. Then the electric element reheats another tankful. You can run out of hot water if two people are showering at the same time, or if you take a shower after the clothes washer or dishwasher have been running. Solar storage tanks are sized to store an entire 24 hour’s worth of hot water because there is no sunshine at night. But this gives you the added benefit that you are less likely to run out of hot water when there are multiple uses at the same time.
- Hotter water. The water delivered by a solar collector panel can be hotter than the thermostat setting on your electric water heater. This means you will have hotter water for the dishwasher and for showers if you you want it. (A mixing valve can be installed on the storage tank to protect you against scalding.)
System performance
Because incoming solar radiation, called insolation, is often interrupted by cloudy or rainy weather and fluctuates in intensity with seasonal changes in the sun’s position in the sky, solar water heating systems are usually sized to collect and store an entire 24 hours or more worth of solar heated water to meet morning and evening demands. A modern solar water heating system storage tank will usually have a backup electric heating element to meet unusual peaks in hot water use or extended periods of very cloudy or rainy weather.
While solar water heaters are viewed as “pre-heating” systems in many regions of North America, Florida enjoys solar levels that allow solar water heating systems to economically meet 85 to 90 percent of the your annual hot water needs.
What about cloudy weather?
Good question. Actually, a solar water heating system will typically collect about half the solar energy of a clear, sunny day on an overcast day. If you have ever had the experience of going to the beach on an overcast day and still getting a sunburn, you will understand this phenomenon. Clouds block many of the visible wavelengths of sunlight, but much of the solar energy still gets through.
Will my water be hot enough?
Yes. Solar heated water is often hotter than the thermostat setting on your water heater. In fact, for safety reasons our systems include mixing valves to make sure the hot water going into your house isn’t too hot. On the other hand, sometimes we may have extended periods of very cloudy and rainy weather. During these periods, a backup electric heating element in your water heater / storage tank will automatically heat water to the water heater’s thermostat setting.
Will I have hot water during cold weather?
Yes. Solar water heating collectors typically deliver excellent performance in Florida during cold weather because the sky is very clear during winter high pressure waves. The glass cover plate and insulation inside the collector prevent collected heat from escaping to the outside air.