Solar Hot Water

This is a basic introduction to solar hot water and how these systems work.  For information on how solar hot water collectors are incorporated into EEC's home, please visit the Integrated Systems section.

Solar water heaters utilize the sun's energy to heat water, making them an environmentally sound way to reduce energy bills. According to the U.S. Department of Energy, a solar thermal water heater will drop your water-heating bill an average of 50 to 80 percent, saving a family of four living in a 2500 SF home around $400 a year on hot water costs. Solar hot water can be integrated with radiant hydronic heating to provide an energy saving, low cost, and comfortable solution for home heating and cooling demands..

Solar hot water can meet part or all of a home's domestic hot water needs and comes in a variety of systems and designs, each of which differs in cost and performance. Standard installations of solar hot water systems in Colorado are on average 65% efficient, meeting only 65% of the hot water demands of a home. Energy Environmental Corporation installs a special system design, equipped with wireless sensors and controls, which can result in solar factors of up to .9, meeting 90% of hot water demand.

How It Works

The components of a solar water heating system typically consist of a solar collector to absorb the sun's heat, one or more hot water storage tanks, a heat exchanger, and a back-up energy source. Below is a diagram, courtesy of Viessmann, which outlines the basic way a closed loop solar hot water system works.

When there is sufficient heat to be drawn from the collectors, a controller automatically activates pumps which circulate a special heat transfer fluid. The heated solar fluid is then circulated from the collectors, through the heat exchanger, where heat is transferred to water in the storage tank. The cooled solar liquid is then pumped back to the collectors to be reheated by the sun. This circulation and hot water heating will continue as long as enough heat energy is being provided by the sun. During times when there is little or no sun, a backup heating system will be activated to provide adequate hot water. In EEC's home, a water-to-water geothermal heat pump will help maintain the water temperature in the hot water tanks that have been heating by the solar thermal collectors.

solar hot water heating diagram from Viessman

Diagram of a closed loop solar hot water system. Image courtesy of Viessmann Manufacturing Company Inc.

Platinum LEED Home Solar Hot Water System

EEC is working with Arapahoe Community college to provide renewable energy training to students. Below, trainees help out with the installation of Viessman solar hot water panels on EEC's platinum LEED home.

installation of solar thermal collectors platinum leed home

Below, rear view (south facing) side of the home with solar photovoltaics (right) and solar hot water panels (left).

solar pv and solar thermal platinum leed home


Following are descriptions and links to the solar hot water components and products incorporated in the Platinum LEED Home. Please contact us for more information on a solar hot water heating system for your home.

Viessmann Temperature Controller

Viessmann solar controls are capable of managing a wide variety of applications - from basic to very complex and give you the versatility and the power to meet the various system design requirements. The Viessmann SCU 124 Temperature Differential Controller is for use with basic single load systems.

Benefits at a glance:

  • Up to 4 temperature sensors Pt1000
  • Heat balancing
  • Function control
  • User-friendly operation by simple handling
  • Solar operating hours counter and thermostat function optionally
  • Viessmann Vitosol 200 F Solar Collector

    Viessmann Vitosol solar flat-plate collectors are one of the industry's highest-rated collectors. The Vitosol 200-F flat plate solar collector is attractive not only for its low investment cost but also for the energy it saves. With the new high efficiency Sol-titanium coating solar energy harvest is now even more efficient. Durable, corrosion resistant construction using materials such as powder coated aluminum, copper and stainless steel, as well as 3.2 mm special low-iron solar glass ensure a long service life and maintain high efficiency for years to come.

    Benefits at a glance:

  • Optimized collection of solar energy thanks to highly efficient Sol-titanium coating.
  • Collector surface area: 25 sq.ft/2.3 sq.m. Two versions available for horizontal (SH2) or vertical (SV2) installation.
  • High efficiency through selectively coated absorber, integrated piping and extremely effective thermal insulation.
  • Flexible connection pipes facilitate short installation times. Up to 12 collectors can be quickly installed in series using a convenient plug-in system.
  • Durable, corrosion resistant construction using materials such as powder coated aluminum, copper and stainless steel, as well as 3.2 mm special low-iron solar glass and non-degrading thermal insulation.
  • Universal application: on flat and sloped roofs, on top of roof coverings, or for freestanding installations.
  • Viessmann Solar Divicon

    With its all-new fully-integrated design, the new generation Solar-Divicon pumping station from Viessmann combines all required hydronic components of a closed-loop solar system into one convenient assembly. Contractors no longer have to worry about getting a separate system fill manifold or air separator, this assembly has all you need.

    Compact, fully assembled and equipped with all NPT fittings, it's fast and easy to install and eliminates piping errors right from the start. It handles all hydronic and safety functions and works with any Viessmann or third-party closed-loop solar system.

    Benefits at a glance:

  • New, fully-integrated design
  • No other components between collector and tank required
  • Fast and easy installation
  • NPT fittings and imperial units on all gages
  • Works with Viessmann or third-party closed-loop solar systems
  • viessmann solar divicon

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