Sun Aire

Air Collectors for Home Heating

Liquid Collectors for Solar Hot Water & Radiant Floor Systems

Other Solar H2O Products & Parts

• Heat Exchangers

• Storage Tanks

• Complete Systems

• Batch Water Heaters

Other Solar Hot Air Products & Parts

• Backdraft Dampers

Other Solar Hot Air Products & Parts

• Backdraft Dampers

¡800J S4S-0311 • www.aaasalar.cam[email protected]

2021 Zearing NW, Albuquerque, NM 87014

Energy Efficient Refrigerators and Freezers

Available in 12/24 VDC or new 12/24 VDC / 120 VAC

Runs on 70 watt panel and 110 amp/hr battery in most climates!

Features:

Thick polyurethane insulation

Patented low frost system

Automatic operation

Easy to clean interior

Interior light

Contact us at (915)821-0042 www.SunDanzer.com | [email protected]

V^EL

Get Solar Access and Shading Data On-Site with the Touch of a Button.

The Solmetric SunEye™ is all you need.

• Integrated fish-eye lens and digital camera

• Captures image of obstructions and superimposes sunpaths

• Works anywhere in the world

• Accounts for panel tilt and orientation

• Simulates removal of shade-causing obstructions

• Generates reports and archives data

The Solmetric SunEye™ is all you need.

• Integrated fish-eye lens and digital camera

• Captures image of obstructions and superimposes sunpaths

• Works anywhere in the world

• Accounts for panel tilt and orientation

• Simulates removal of shade-causing obstructions

• Generates reports and archives data

To purchase, contact 1-800-967-6917 or www.dcpower-systems.com

To purchase, contact 1-800-967-6917 or www.dcpower-systems.com

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Solmetric

www.solmetric.com

GPS Add-on:

• Automatically detects location for each Skyline

• Compatible with new and existing SunEye units

GPS Add-on:

• Automatically detects location for each Skyline

• Compatible with new and existing SunEye units

Helping The Do-It-Yourselfer:

• Code Compliant System Engineering

• Load Calculation and Design

• Renewable Energy Components for: ^ Solar, Wind and Hydro ^ ^

• Pre-Wired Systems Also Available

Experienced & knowledgeable!

SarahSolarsays:Thanks!

SarahSolarsays:Thanks!

www.mavericksolar.com 512-919-4493 [email protected]

▼ . Improving a SHW System's Efficiency by Andrew Goldbaum

I considered installing a solar hot water system for many years, but delayed for financial reasons. Then, heating oil approached $4 per gallon, and it finally made economic sense. After considering my family's hot water usage, the federal and state tax credits, and a system payback of just five to six years, it seemed financially irresponsible not to install one. I contacted an experienced local solar contractor and had him install a three-collector, 120-gallon antifreeze/ drainback system that would preheat water for an existing 50-gallon hot water tank, which is indirectly heated by an oil-fueled hot water boiler.

Even before the installation, I knew my system would have two efficiency issues. The first was that even though the solar hot water tank might be filled with 150°F water, if no hot water was being used, the existing water heater tank would slowly cool as it had always done. This meant that occasionally the boiler would fire just to reheat it a few degrees, despite having a tank of "free" solar-heated water right next to it. When I witnessed my boiler firing up on a hot, sunny, summer day, I became determined to find a solution.

The second inefficiency has to do with heat energy that becomes "trapped" in the drainback tank: At the end of a sunny day when the collector circulator pump shuts down and the

Who: Andrew Goldbaum

What: Drainback solar hot water system

When: August 2008

Where: Warwick, New York

Why: I needed to cut my oil bill

The guts of Andrew's solar hot water system, now running better with a little automatic—and manual—intervention.

The guts of Andrew's solar hot water system, now running better with a little automatic—and manual—intervention.

Left: An X-10 transmitter recognizes 125°F water in the solar storage tank and transmits a signal.

Right: The X-10 appliance module receives the signal and energizes the instant hot water circulator.

Right: The X-10 appliance module receives the signal and energizes the instant hot water circulator.

solar tank temperature equalizes, the tank water might be 135°F. After filling the bathtub and running a load or two of laundry, the temperature at the bottom of the storage tank might be reduced to 75°F, while the top of it might be 130°F. However, the glycol, just sitting in the drainback tank, might be 140°F. If during the evening, that heat could be transferred into the solar storage tank, it would heat the water in the bottom of the storage tank to about 105°F. This would:

• Lessen or even stop the use of the boiler in the evening during high hot water use.

• Delay the need for backup heating if the following day is not sunny enough to activate the circulator.

• Reduce heat loss, since the solar storage tank is better insulated than the drainback tank.

• Result in higher system efficiency, since collectors operate more efficiently when heating glycol from a lower temperature to a higher one (100°F to 120°F, for example, as opposed to 130°F to 150°F). The next day, more hot water will be available sooner.

System Description

Three SunEarth EC32, 8- by 4-foot collectors. Despite their slightly higher cost, I chose SunEarth's Empire series black chrome collectors for their higher efficiency compared to the more standard, selective-black-painted collectors. The collectors are SRCC approved, which is important for tax credit purposes.

Two Grundfos UP 26 circulator pumps. In this system, one circulator alone couldn't pump the glycol the almost-40 feet from the basement to the rooftop collector array, so a second circulator was added in series. This nearly doubles the pressure and head, costing less and using less electricity than a single larger circulator pump.

One Rheem 120-gallon Solaraide tank. The Rheem tank with integral heat exchanger is an industry standard for solar hot water storage. The Whirlpool 19-gallon electric water heater, which serves only as the drainback tank—not as a heated backup—was chosen because of its convenient connections. It's fairly well-insulated and holds 9 more gallons of glycol than a typical drainback tank, but costs much less. The extra glycol provides additional heat storage.

One SunEarth AECA differential controller. The controller has three temperature inputs from sensors: T1, at the solar collector output; T2, at the bottom of the storage tank; and T3, at the top of the storage tank. The controller activates the circulator based on the difference between T1 and T2, so that when the collector fluid is hotter than the storage water, the pump comes on. When T1 or T2 is too high, the controller shuts down the pump and the system drains. T3 temperature is for monitoring purposes only, and does not affect pump operation.

Solution: Reducing Fossil Fuel Use

The solution to my first efficiency problem was to install an instant hot water circulator (IHWC). This eliminates the issue where the boiler turns on to reheat the existing water heater tank despite having plenty of hot water available in the solar storage tank. This device also eliminates the annoyance of waiting for hot water to arrive at the faucet.

An IHWC is installed under the sink that is farthest from the water heater and monitors the temperature of the hot water at the sink. When the temperature drops below an adjustable set point (100°F, in this case), it turns on its circulator pump, which draws hot water from the water heater, keeping hot water at the faucet all the time. If not used in the sink, the water returns to the tank via the cold water line. When the hot water line reaches the required temperature, the IHWC pump shuts off. In this way, hot water is kept very close to all the faucets along the same hot water supply line.

While having on-demand hot water is nice, I wanted to save oil, not use extra by drawing water from the water heater tank during times when solar-heated water of sufficient temperature was not available. I accomplished this by plugging the IHWC into an X-10 appliance module and connecting an X-10 PowerFlash transmitter module to a small thermostatic switch installed at the top of the solar tank.

Only when the instant hot water circulator is powered by the X-10 appliance module and when it senses water temperature below 100°F at the faucet will hot water circulate.

When the solar tank is at 125°F (5°F higher than the water heater tank's set point), the thermostatic switch closes and causes the X-10 transmitter to send a signal through my home's electrical wiring to the appliance module at the IHWC to power the IHWC's automatic operation. When the temperature in the solar tank drops below 125°F, the thermostatic switch opens, and the transmitter signals the appliance module to turn off the IHWC. This means the IHWC runs only when the tank temperature is more than 125°F and the IHWC temperature at the sink is less than 100°F. With the system properly adjusted, the boiler should stay off as long as sufficiently heated water is available from the solar storage tank. (For homes with 240 V single-phase service split into two 120 V legs, both X-10 modules must be on the same leg to communicate.)

Solution: Addressing Trapped Heat in the Drainback Tank

The second efficiency issue—where heat becomes "trapped" in the drainback tank—is more complex. Provided a good amount of hot water has been used (cooling the bottom of the storage tank), and it's not too cold outside, the SunEarth controller can be manually set to run the circulator. But if it's too cold outside and glycol is circulating, the cold solar collectors will absorb usable heat from the glycol and begin to cool the solar hot water tank. If it's warm out and the circulator is running, it will quickly heat up the collector until it is hot enough to fool the controller into thinking the sun is shining, keeping the system running. At this point, the controller should be set back to automatic mode. When the solar controller finally shuts off the circulator, the storage tank will be much warmer, having absorbed much of the drainback tank's residual heat. Nineteen gallons of 140°F glycol can raise the bottom third of the 40-gallon tank from 75°F to 105°F. This is more than enough heat to take a hot bath and saves about 0.1 gallons of oil.

Temp. Sensor:

Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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