Why A Solar Hot Water System?

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Solar Hot Water Systems Save Money

Most households get their domestic hot water for washing dishes and clothes, bathing and cooking from a water heating system.

The system may vary from an electric or gas-fired water heater, to a boiler or furnace that are also used for heating the home. Using electricity for heating water is expensive. Using electricity to heat water will keep pinching the hip pocket nerve. Also, gas water heaters will be phased out too, despite them being a cheaper form of water heating than using electricity, they present safety problems when used in confined spaces.

There is a solution. Using a solar hot water system is one of the most viable, economic and energy efficient water heating systems available today. It uses radiant heat from sunlight as the energy source. Because the heating doesn't come from burning fossil fuel, there are no pollutants and greenhouse gases like carbon dioxide, nitrous oxides, and sulfur oxides being released into the environment.

Typical Solar Water System

The solar hot water system produces hot water throughout the year, reduces your carbon footprint, and lowers your energy bills. Yes, sunlight is free but solar hot water systems are not.

After the initial purchase and installation cost; your future hot water is almost free. The upfront cost of purchasing and installing a solar water heater system is usually higher than for conventional water heating systems but these units are very efficient. 

Remember, the solar water heating system returns more in savings than an electrical or gas conventional system, where you pay more for the heating energy or fuel.

Solar Hot Water System Savings

The amount of money you can save through having this system installed is dependent on several factors like:

  • Hot water usage
  • Temperature for the hot water
  • System's performance
  • Your geographic location and solar access
  • Available incentives and financing costs
  • The cost of conventional fuels (natural gas, oil, and electricity)
  • The cost of using the backup of conventional fuel for heating your water

How The Solar Hot Water System Works

Solar water heating systems use solar panels called collectors, which are usually fitted onto the roof. These collector panels absorb the heat from the sun to heat up a fluid which is usually water.

The hot water is then stored in an insulated storage cylinder to keep the water hot from losing heat. An immersion heater can be used as a back-up to heat the water further in order to reach the desired temperature. This also comes in handy when you have limited or no sunlight access such as in winter storms and at night.

There are three types of solar water heating panels; evacuated tubes, Integral collector storage (ICS) systems, and flat plate collectors.

  • 1
    Evacuated tubes solar collectors convert energy from the sun into usable heat in a solar water heating system.
  • 2
    Flat plate collectors are fixed on the roof tiles or integrated into the roof. Flat-plate collectors generally are considered more efficient for residential applications while evacuated tubes are best suited for commercial applications.
  • 3
    ICS is used mainly in mild-freeze climates where the outdoor pipes could freeze in severe, cold weather.

A short video might help you understand the working of a solar water heater.

Economic Benefits of Solar Hot Water

By installing a solar water heater, you can bring down your water heating bills by 50%–80%. That figure depends on the amount of water you need heated and how much is used. Moreover, by relying on your installed roof top solar hot water system, you are not going to be affected by gas shortages and electricity price swings. You might even add a solar PV system to reduce that electric cost as well.

If you're building a new home or refinancing, the economic benefits of solar heating are attractive. You can often include the purchase price of a solar water heater in your new home within a multi-year mortgage. In some places there are federal income tax deductions for mortgage interest available for the solar.

So, you can be saving money each month on hot water. Month on month, you save more than you would paying for electricity and gas for a conventional heater, making the solar investment worthwhile. A solar water heating system can deliver 50 to 90 percent of the daily hot water needs of an average home through the colder months.

There will always be variation due to the different usage requirements of every household plus the difference for location affecting the amount of sunlight received.

With solar collectors you can reduce the amount of energy being used for heating. You will still need a backup: an electric, gas or wood heating source to compensate for solar energy shortfall. Even then, the proposition is profitable. This is because the sun's natural energy provides almost 75 percent of your heating needs, thereby substantially reducing the amount of energy needed for heating through back-ups.

Solar Hot Water

Solar Water Heater Mechanics

Solar Hot Water System Savings

By using solar hot water systems you will attract the following benefits:

  • Lower energy costs for your business and/ or your household
  • Reduction in greenhouse gas emissions
  • Improved energy competitiveness
  • Better energy security
  • Lower investment is needed in developing your alternative energy resources like solar PV and infrastructure

The solar energy factor (SEF) and solar fraction (SF) are used to determine a solar water heater's energy efficiency. Solar energy factor is defined as the energy delivered by the system divided by the electrical or gas energy put into the system.

Higher the number, the more energy efficient is the heating system. Optimum solar energy factors range from 1.0 to 11. Systems with solar energy factors of 2 or 3 are most widely used.

Another solar water heater performance measuring unit is the solar fraction. Solar fraction is the amount of energy provided by the solar technology including tank standby losses, divided by the total energy required. Higher the solar fraction, the greater is the solar contribution to water heating.

This reduces the energy required by the backup water heater. The solar fraction varies from 0 to 1.0 with zero for no solar energy contribution to 1.0 for all energy being provided by solar. The solar savings fraction of a particular system is dependent on many factors such as the load, the collector and storage sizes, the operation, and the climate. Standard solar factors range between 0.5 to 0.75.

Solar Hot Water

Structure of a Solar Water Heater 

Conserve Energy With A Solar Hot Water System

Heating water is one of the major energy consumers for a household. It accounts for almost one-fifth to one-quarter of an average U.S. household's energy usage. When you are working toward saving energy you might consider an energy audit to determine where energy is being used and then conserve power through using more efficient appliances. With water heating using a significant portion of home energy, the first step should be purchasing an energy efficient water heater.

Once water heating is taken care of, there are some supplementary consideration for adding to the saving from the solar hot water system. These consider methods to reduce the amount of hot water being used in the household:

  • Fixing leakages- If you repair the leaks in fixtures (faucets, shower heads) and pipes you then use the hot water produced. A leak producing one drip of per second wastes 1,661 gallons of water per year, which at current water cost amounts to $35 per year. If the leakage is within the water heater’s tanks then the water heater itself will need to be replaced.
  • Low-Flow fixtures - According to US Federal regulations, new shower head flow rates can't exceed more than 2.5 gallons per minute (GPM) at a water pressure of 80 pounds per square inch (psi).

Faucet flow rates can't exceed 2.5 GPM at 80 psi or 2.2 GPM at 60 psi. By installing low-flow fixtures you can make considerable water savings (in the order of 25%–60%).

Strategies For Reducing Solar Hot Water Costs

Fixtures manufactured before 1992 probably need to be replaced to make your solar water system energy efficient. You can do a simple test at home to determine the water flow of the shower heads: 

  • 1
    Place a bucket with markings showing gallons under your shower head
  • 2
    Turn on the shower head to reflect the normal water pressure you use
  • 3
    Time the number of seconds it takes to fill the bucket to the 1-gallon (3.8 liters) mark
  • 4
    Anything less than 20 seconds to reach the 1-gallon mark warrants a new shower head

Current kitchen faucets come equipped with aerators that restrict flow rates to 2.2 GPM. Similarly, modern bathroom faucets restrict flow rates to between 1.5 and 0.5 GPM.

Reducing the amount of hot water wastage offers an inexpensive way to save energy. Because less hot water is wasted less pressure is on the solar water heater to heat so much water.

  • Turn down the thermostat on your water heater, and insulate your water heater along with the hot and cold water pipes.
  • Use energy efficient dishwashers and clothes washers.

Check the Energy Efficiency of a Solar Water Heater

When looking for an energy efficient hot water system for your house, two key factors need to be considered and evaluated:

  • The size and type of water heater that suits your hot water requirement, and
  • The type of fuel it will use

Instantaneous (tankless) water heaters are energy efficient, but due to their lack of storage, they are not a feasible choice for families. A hot water system in a house should be equipped to handle multiple and simultaneous uses of hot water.

These instantaneous water heaters save energy because they only heat water when it is needed. So, in that way they are more efficient than a conventional storage water heater.

The Future of Solar Heating

Homeowners are installing solar hot water systems because they benefit from saving electricity (therefore money) and getting tax rebates. A large population is still to be convinced that there are benefits to going with solar PV or converting to solar thermal heaters for their hot water.

The technology is simple to install but there are promotional and educational gaps. As with solar PV installations, the upfront cost of the installed solar hot water system also tends to be an impediment for some people who have considered and said "No".

Solar Hot Water

Portable Solar Water Heater

The solar PV electricity generation technologies along with the solar hot water heating technologies are bound for steady progressive growth. Research, adaption and innovation with these solar technologies constantly improves their efficiency and their applications. There are hybrid collectors available which can now provide hot water and electricity at the same time.

The price of solar voltaic panels has dropped leading to making hot water using solar electricity less expensive. You can now connect roof solar panels via an inverter (that costs $300 to $500 dollars) directly to a standard instantaneous electric hot water heater.

There is free or lower priced electricity with solar power plus tax incentives to help with energy efficiency. Due to the cost of power and the efficiency of electric water heater heating thermal solar water heating can make less economic sense to those householders with a PV solar system.

The increased price of fossil fuels and rising awareness of solar options are contributing to the growth of solar PV systems being used in heating water. The efficiency of thermal solar for water heating makes the solar hot water option economically attractive for homes that have not installed a solar PV but need to replace their hot water system.

Check out the price of a solar hot water system for your home by clicking here.



  1. I’m glad I discovered a solar water heating system here which enables an eco-friendly approach to the traditional. This is because it is very efficient and could help you save a lot of fuel costs in the long run. We should really consider a replacement for the outdated system since it has been around since our grandmother was still in the late 20′.

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