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Solar Hot Water, Heating and Cooling Systems

This chapter sponsored by:
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Solahart Energy Auditing

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Dripping Springs, TX 78620
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Since 1953, Solahart has installed over 600,000 units in more than 80 countries. All Solahart hot water systems are backed by a 5 year limited warranty.

Call (512) 606-2366 for a free solar Energy Audit in the Greater Austin area.


Solar Hot Water, Heating and Cooling Systems Contents:

CSI NUMBERS
DEFINITION
CONSIDERATIONS
COMMERCIAL STATUS
IMPLEMENTATION ISSUES
GUIDELINES

RESOURCES

CSI Numbers:

DEFINITION:

 The solar systems that will be discussed in this section are not a part of a building's structure. The function of the solar energy equipment is to convert sunlight to heat that can be used for: (a) space heating; (b) space cooling; (c) domestic hot water.

CONSIDERATIONS:

Solar systems should be employed only after extensive conservation strategies have been implemented. Solar energy systems typically have a high initial cost and extremely low operating costs. To reduce the high initial costs, reduce the size of the required system by the load that the solar system will need to provide. In space heating and cooling applications, the home should be weatherized and insulated to very high standards. In water heating applications, hot water piping should be insulated and water conserving fixtures should be used.

The goal of the solar system should not be to accomplish 100% of the home's heating, cooling, or water heating needs under all conditions. The system should be sized to reflect seasonal variations in demand and in the sun's heating characteristics. Additionally, by combining systems to perform multiple functions (i.e. space heating and water heating), the solar system investment can provide a return all year.

The City of Austin will provide a rebate under the Appliance Efficiency Program for solar domestic hot water systems if installed in an all-electric home. There are no tax incentives currently available to assist in the first costs of solar systems, but there is an exemption for solar energy devices from being appraised for property tax. There has been a dramatic reduction in the number of businesses and equipment relating to solar systems since federal tax incentives were eliminated in 1985. Only a few businesses in our area provide solar systems.

Solar installations are governed by City Ordinance 900104-J. This ordinance follows the 1988 Uniform Solar Energy Code established by IAPMO (International Association of Plumbing and Mechanical Officials). Building, plumbing, and mechanical (when the system provides space conditioning) permits are required for solar installations. There are several types of solar systems in each of the categories of space heating, water heating, and space cooling. Of the three general categories, space cooling by solar energy is the least cost effective except in passive applications, which are discussed in the Passive Solar Design section.

Commercial
Status		 Implementation
Issues
technology suppliers cost financing public regulatory
Active Solar Heat
Active Solar Cooling
Passive Solar Water Heating
Active Solar Water Heating
Legend
green Satisfactory
yellow Satisfactory in most conditions
red Satisfactory in Limited Conditions
black Unsatisfactory or Difficult

COMMERCIAL STATUS

TECHNOLOGY:

Active and passive solar space heating and water heating, are well-developed technologies. Active solar space cooling is marginally developed.

SUPPLIERS:

There are adequate suppliers on a national basis for all solar equipment except space cooling. There are few local suppliers.

COST:

Solar domestic water heaters are reasonably priced ($1000-$3500) and can show pay backs of four to seven years depending upon the fuel displaced (electric or gas). Space heating systems can vary from inexpensive wall heaters ($800) to costly large central systems ($4000+). Space cooling systems are not currently competitive. Reducing demand to keep systems small helps control costs.

IMPLEMENTATION ISSUES

FINANCING:

Most lenders are not knowledgeable of solar systems.

PUBLIC ACCEPTANCE:

There are problem areas associated with the general public perception of solar systems: solar may be considered futuristic; some may believe new technological breakthroughs are needed to make solar viable; solar systems are considered uneconomic; and, the business instability of solar system providers during the early 1980s. A primary concern for owners of a solar system is whether it can be maintained by conventional means (the owner does not have to assume extraordinary responsibilities).

REGULATORY:

City Ordinance 900104-J adopted the 1988 Uniform Solar Energy Code of IAPMO (International Association of Plumbing and Mechanical Officials). The "Solar Energy Code" is found in Chapter 13-8-500 of the Land Development Code in Article VII. The Solar Energy Code presents equipment and installation standards. Building, plumbing, and mechanical permits are required for space conditioning.

GUIDELINES

  • 1.0 Introduction

    • Solar energy can be captured for use in a home in several ways. This section will look at using solar energy to heat water and/or air. The hot water created by a solar system can be used for domestic hot water or space heating. Hot air solar systems are primarily used for space heating.

    The fundamental requirement for a solar system is to have a sunny location where the solar collectors can be located.

    Collectors can be oriented as much as 30 degrees off of south and still function well. Similarly, the slope of the collectors can vary by plus or minus 15 degrees without significantly harming the performance of the system.

  • 2.0 Active Solar Domestic Water Heating

    • The active water systems that can be used to heat domestic hot water are the same as the ones that provide space heat. A space heat application will require a larger system and additional connecting hardware to a space heat distribution system.

  • 3.0 Active Solar Space Heating

    • The active solar space heating system can use the same operational components as the domestic water heating systems, but ties into a heating distribution system that can use heated fluids as a heat source. The distribution system includes hydronic radiator and floor coil systems, and forced air systems.

    Solar collectors are also constructed that heat air. The hot air developed in such collectors can be used directly in the home during the daytime or stored in massive materials (rock or water).

  • 4.0 Active Solar Space Cooling

    •  Solar space cooling is quite costly to implement. If the solar system is used for space cooling only, installed costs can run $4,000-$8,000 per ton. It is best to use a solar system that serves more than just the cooling needs of a house to maximize the return on investment and not leave the system idle when cooling is not required. Significant space heating and/or water heating can be accomplished with the same equipment used for the solar cooling system.

    SCHEMATIC OF SOLAR ABSORPTION COOLING SYSTEM

    Figure 3
    SCHEMATIC OF SOLAR ABSORPTION COOLING SYSTEM

    T = system flow sequence

  • 5.0 Passive Solar Water Heating

    •  A passive solar water heating system uses natural convection or household water pressure to circulate water through a solar collector to a storage tank or to the point of use. Active systems employ pumps and controllers to regulate and circulate water. Although passive system are generally less efficient than active systems, the passive approach is simple and economical.

    Passive water heating systems must follow the same parameters for installations as active systems - south facing unshaded location with the collector tilted at the angle of our latitude. Since the storage tank and collector are combined or in very close proximity, roof structural capacities must accommodate the extra weight of a passive system which can be 300 pounds or more.

    RESOURCES

    PROFESSIONAL ASSISTANCE

    COMPONENTS / MATERIALS / SYSTEMS

    GENERAL ASSISTANCE:

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