Solar Energy Technology

Solar energy refers to the use of the sun's rays rather than electricity, oil, kerosene or natural gas to provide heat for a wide variety of uses. Sunlight strikes and heats an "absorber" surface within a "solar collector". The water to be used flows through the absorber that has been warmed by the sun and picks up the heat from it. An analogy is often made to a garden hose that sits in the sun and then warms the initial water passing through it.

For the household water, the concept is the same. A flat panel is used that is made up of many small tubes. The size and number of tubes as well as the material of the absorber effect how well the sun's warmth is captured and transferred to the water. (This is referred to as the thermal performance rating of the product.)

The sun's energy heats the solar panel tube and the energy is transferred to the water

The smaller the tubes, the slower the water flows through them which in turn enables more heat to be transferred to the water. Likewise, if the number of tubes used is increased, more water can be exposed to the heat and therefore warmed. Most tubing is made of durable, lightweight, ultraviolet-resistant polyolefin material blended with proprietary additives determined by each manufacturer.

In addition to the solar panels, the other major parts of a solar heating system include the circulation system and the storage tank. For pools, the circulation system is the pump and filter, and the storage tank is the pool itself. For hot water heating systems, the hot water tank is the storage tank and in some situations (e.g., with gas hot water systems) an additional storage tank is required.

Fafco's panels are made of durable, lightweight, ultraviolet-resistant, polyolefin material blended with proprietary additives at our own USA plant under exacting, quality-control standards.

ENGINEERING SPECIFICATIONS

OVERALL SYSTEM

The following shall be the specifications for the solar water heating system. The system shall be a FAFCO polymer drainback type that is freeze resistant, overheat protected, using unglazed collectors and polymer connection tubing.

COLLECTOR The collectors shall be FAFCO unglazed UV resistant polymer collectors designed specifically for solar domestic water heating. The dimensions of the collector shall be 144 inches in length, 24 inches in width with a ¼” or less absorber thickness. The weight of the collectors shall be less than 1 lb/sq ft when full of water. The collectors shall be fully chemical and corrosion resistant beyond the capability of any metal. The collectors shall have excellent long-term weatherability as verified by 35 years or more of field installed product, accelerated outdoor exposure, and other extensive laboratory testing. The maximum operating pressure shall be 30 psi and maximum operating temperature shall be 200 degrees-F.

COLLECTOR MOUNTING HARDWARE AND ROOF JACKS The mounted collector shall be anchored using FAFCO mounting hardware. The roof jacks shall be FAFCO low profile galvanized steel roof jacks with 5/8” I.D. water tight rubber grommets.

PLUMBING Plumbing of the solar collectors to the drainback tank and circulation module shall be 1/2'” I.D. tubing rated for temperatures up to 200 degrees-F. Connections shall be of the push fit type with EPDM seal that require no tools for securing. Mounting clips shall be used to secure the plumbing every 3 feet. All plumbing exposed to sunlight shall be either be made of UV protected material or covered with UV protected material. A drain valve shall be installed above the circulation module to drain the drainback tank and solar loop.

DRAINBACK TANK The drainback tank shall be made of a high temperature polymer capable of withstanding operating temperatures up to 200 degrees-F. The capacity shall be 10 gallons with dimensions of 33in. x 18in. x 5in.. The drainback tank will have an integrated sightglass for viewing the solar loop water level. The drainback tank will be vented to the atmosphere at all times by way of a vented cap.

CIRCULATION MODULE The circulation module shall consist of a single unit with preassembled pumps, heat exchanger, filter, and wiring. The dimensions shall be 11in. x 11in. x 9in.. The voltage input shall be 120 volts. The heat exchanger shall be a copper brazed stainless steel plate heat exchanger. The potable loop shall consist of a low head pump with union connections and integrated 20 mesh filter connecting the heat exchanger to the solar tank. The solar loop shall consist of a high head pump with union connections connecting the drainback tank and solar collectors to the heat exchanger. The pumps shall be prewired inside the enclosure such that a single cord exits the enclosure through a protection grommet. The vented enclosure shall be made of a rigid polymer and shall be capable of easily opening to access or replace inner components.

SOLAR TANK CONNECTION The solar tank connection shall be a coaxial tank adapter which allows the drainport of the solar tank to both feed and return the water in the solar tank to the circulation module. The coaxial tank adapter shall be have a connection for the solar tank drain port, drain bibb, inlet connection to the circulation module, and outlet connection to the circulation module. Flexible hoses approved for connecting domestic water heaters shall be used to connect the coaxial tank adapter to the circulation module.

SOLAR CONTROLLER The solar controller shall activate and deactivate the circulation module based on temperature difference between the sensor installed at the bottom of the solar tank and the sensor installed adjacent to the solar collector(s). The controller shall have digital accuracy and an animated LCD display that provides real time operating temperatures at the solar collectors, solar tank bottom, and optional solar tank top. The controller shall have varistor high voltage spike protection and fused output protection for the pump circuit. The sensors shall be either RTD type 1000 Ω or thermistor type. The controller shall have an adjustable high limit temperature of for the storage tank. There shall be an accessible side-mounted on, off, and auto switch on the controller housing.

STORAGE TANK The solar storage tank shall be approved for domestic water heating use with a minimum pressure rating of 150 psi. The tank shall include a pressure/temperature relief valve specified for 210 degrees-F at 150 PSI.