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Natural Awakenings Charlotte

Here Comes the Sun - Solar Hot Water: A first step to going green

By Justin Rowell

Want to go green at your home but don’t know where to start? Well, here comes the sun. A solar water heater is an easy initial investment in renewable energy. Next to heating and cooling, water heating accounts for a large share of a home’s energy use. Solar hot water systems can reduce the average family's energy costs to heat water by 20 to 40 percent and save the US millions of barrels each year.

Many people are interested in using solar power for their home or office, but are inhibited by economics. The notoriously high costs of a residential PV (photovoltaic) system can easily exceed $30,000. Conversely, solar hot water (SHW) systems typically cost less than $7,000. When you consider an additional 30% federal tax credit (capped at $2000) and a 35% state tax credit (capped at $1400 for SHW only, or $3400 for SHW with space heating), this technology is a no-brainer first step for all who want to move towards energy independence.

How does a solar hot water system work?

While a PV system uses photovoltaic cells to convert the sun’s light into electricity, a SHW system uses the heat from the sun to make water hot. This simple, time-tested system is comprised of a collector (where the suns heat is collected and transferred to the fluid), storage tank, and pipes and pumps that convey the fluid between the tank and collector.

SHW systems are generally categorized into two classifications: passive or active and direct or indirect. Passive systems take advantage of the principle that hot fluids rise to convey water through the collector, whereas active systems use electricity to perform this function. The electricity necessary to power the pump in an active system is minimal and can be provided by a very small and affordable PV system if desired. Active systems are more flexible than their passive counterparts due to reduced constraints such as storage tank location. This flexibility usually outweighs the minimal electricity use necessary to achieve it.

Direct SHW systems heat potable water itself in the collectors.  Indirect systems heat a secondary fluid in the collectors and this heat is then transferred to the potable water by means of a heat exchanger.

Stay warm with solar hot water

A SHW system can provide more than just hot water for cooking, bathing and washing needs in the home. This technology can also be used to provide even, comfortable, radiant space heating. Hot water can be piped through coils in the floor or on a wall radiator.  A third option is to pass air from the forced air system around hot water pipes to provide additional heating.

Another common application for SHW technology is for heating pools. This can easily extend the swimming season by 2 to 3 months and reduce the payback period from its already short length if you heat your pool water.

Good for your wallet and the environment

Most SWH systems last 20 to 30 years or even longer. After the typical payback period of 3-10 years, the money you save is money in the bank. Considering the volatility of the stock market, this is a reliable investment that should be made for economics alone.

If energy prices increase annually by 6 percent, an average family can save thousands of dollars over the coming decades by using a solar water-heating system that supplies just 65 percent of their hot water.

Consider the positive environmental benefits and the deal just gets better. A typical residential solar water heater will offset greenhouse gas emissions by about 1,500 pounds of carbon dioxide (CO2) per year. That’s equal to the amount of CO2 released by an average vehicle every 1,685 miles. So look to the sun to make the transition into green living.

Justin Rowell is the owner of Greenmodeling, a local green remodeling company providing products and services that help North Carolinians reduce their environmental impact. He can be contacted at 704-999-4636 or [email protected].

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