HVAC SYSTEM RUNS OFF OF THE SUN by Carolina Cool, Inc.
THE ORIGINAL PROBLEM:
For years a major blockade to having a solar system that can run your entire home and the difficulty associated is because the major rotating equipment in your home, (compressors, motors, and pumps) requires a heavy start up current surge (amperage) to get them going. Once going, the amperage draw levels out, and becomes manageable. For example, when a typical three ton heat pump starts, it requires 30+ amps at 220 volts, but after it is running, the amperage draw levels out to approximately 10. That is why, sometimes when a heat pump starts, that your lights may dim slightly for a second or two. This start up amperage is very detrimental to running off of a battery bank that would typically be utilized in a photovoltaic solar system. The battery bank was simply not capable of this high of amperage draw, and also would certainly shorten the life expectancy.
However, new technologies have come into play.
RENEWABLE ENERGY:
First, let’s talk about our renewable energy system.
The solar system at the Tews utilizes forty eight – 200 Watt Photovoltaic Polycrystalline panels. These will generate approximately 10 kilowatts of power. This power is then routed to a configuration of SMA grid tie inverters, charge controllers, and power management systems. The concept is, in off-grid power scenarios, a SMA Sunny Island connected to a bank of batteries acts as the source of AC power, or the “AC grid” for the location. All power generation devices as well as AC loads are connected together on the AC side of the inverter. During the day, when sun production is high and load use is low, the Sunny Island uses the sun power to charge the batteries. Once the batteries are full, any daytime loads are powered directly from the power generating devices on the AC bus. This eliminates the need for the power for the loads to be run through the batteries, which reduces the number of charge cycles and extends the overall life of the batteries. At night, when power production is low and load use is high, the Sunny Island provides power from the battery bank. In the morning, the batteries are recharged and the cycle begins anew.
In simplified terms, the solar panels charge a battery bank. The battery bank supplies power to a sub-panel. Hooked to the sub-panel is the heating and air conditioning system, and other home appliances if needed. If the battery bank becomes discharged, it will recharge first by the solar system, then from the grid if needed.
One of the greatest benefits of this AC coupling configuration is that it allows virtually any type of power generating device to be connected to the system, i.e. solar, wind, water, even gas or diesel powered generators. Please note this for future reference.
Other features of this solar system include the Sunny WebBox, which allows users to access their system performance data anytime – from anywhere in the world. By logging onto Sunny Portal, users can see their current and historical system performance data displayed graphically. The data collected is stored in common file formats for use in spread sheets, graphs or other websites. In addition, it provides a method for service personnel to receive prior notice to any potential issues or to check the status of a system before traveling to the site. Data storage services to users are free of charge.
MINI SPLIT APPLICATION:
What is a Mini-Split?
A typical definition of a mini split is a split air conditioner or heat pump, without ductwork (ductless), the evaporator is usually mounted in or adjacent to the area being cooled. Other features are typically low air volume, good humidity removal, low noise levels and remote control. In recent years, mini splits have began incorporating multiple indoor units, while still having only one outdoor compressor section.
In the early 1970’s ductless split room air conditioning was developed. The mini split air conditioners and heat pumps were sold mainly in Japan first. In the late 1980’s, Mini-splits became popular in Japan, East Asia and Southern Europe. At the end of the Twenty-first century over one-half of the worlds total shipments of air conditioners are Ductless split systems, however in the US the market is still small compared to the total air conditioning market.
Why use a Mini-Split?
The first answer that most people think of is: I don’t have or can’t install any ductwork. A mini-split simply utilizes copper tubes to transport the refrigerant to the indoor unit. The indoor unit, is in essence, the indoor air handler, and is positioned in the home at the location needed. No ductwork is generally attached.
Other reasons are:
Comfort:
Mini-splits offer greater comfort when compared to traditional air conditioning units. The lower air volume promotes greater dehumidification, the individual control allows for greater personal comfort, and the lack of ductwork added to the anti bacterial filters and construction can prevent the spread of airborne contaminants. And because they can run at lower air volume levels, they also control humidity extremely well.
Noise Levels:
Because the indoor unit shares the living space with you, they are designed for the lowest noise levels possible, 35 Db. The outdoor units are also much quieter than conventional central air conditioning condensing units. This means that they can be installed in areas close to property lines without disturbing your neighbors.
NEW ADVANCES IN MINI SPLIT TECHNOLOGY: INTELLIGENT CONTROLLERS, VRF TECHNOLOGY, AND R410A REFRIGERANTS.
Inverter Technology:
Several manufacturers offer variable refrigerant volume (VRV) or variable refrigerant flow (VRF) HVAC systems. And while there are differences among the various systems, all of them react to changes in heating and cooling requirements by varying the flow of refrigerant. This is accomplished by using highly advanced inverter technology to vary the speed of a 48 volt direct current compressor. An intelligent series of electronic devices called Proportional Integral Derivative (PID) control system gives added control over the rotational speed of the compressors, which allows it to precisely match the amount of refrigerant being delivered to the needs of each zone.
This type of system is not new. In fact, the technology developed in the late ’50s has mainly have found acceptance in Europe and Asia. However, manufacturers have been promoting these systems in North America of late, because of the design flexibility that they offer, especially for retrofit projects, and the energy efficiency of the variable speed compressor, which avoids on/off cycling. The typical VRF system is ductless, but could be ducted. The United States may still be a “ducted” society, but that’s beginning to change.
The VRV (Variable Refrigerant Volume) or VRF (Variable Refrigerant Flow) systems deliver maximum efficiency during partial load conditions by abbreviating the control steps into smaller units, providing precise temperature control in all zones. It also prevents the heavy start up current surge (amperage) that is required of most air conditioning systems. This technology is why these units can be powered by a battery bank.
Precise Room Temperature Control:
One outdoor unit connects to as many as nine indoor units. (50% to 130% ratio of indoor capacity to outdoor capacity.) Each indoor unit incorporates an electronic expansion valve that continually controls the flow rate of refrigerant. In this way, the VRV system maintains a nearly constant room temperature without the typical temperature fluctuations that occur with a conventional ON/OFF control system. The extremely refined PID control maintains room temperature to within ±1°F of the set temperature. With immediate response to changing room capacity heat loads and varying sun exposures throughout the day, everybody stays cool and comfortable. The system also ensures individual zone temperature control so each room can be adjusted for personalized comfort. Advances with the indoor units now also allow some ducting for multiple room applications. Overall, the Mini Split system provides healthier air quality, potentially reducing sick days and time off from school and work.
Less Frequent Stop/Start Cycle:
By using variable speed compressors to regulate capacity, switching losses or power surges are minimized.
THE PERFECT STORM:
A “perfect storm” by definition is a convergence of events that form an environment never experienced before.
Carolina Cool has done this groundbreaking installation for the Tews. Others are in line to do the same. For these customers, it is revolutionizing the way they save energy, and bring us all a step closer to energy independence. This unique installation that delivers solar energy to the grid for buy-back purposes and off-grid power to a zoned, ducted HVAC system of the home effectively reduces total household power consumption by up to 70%, depending on conservation of usage. Other key benefits include uninterruptible power for heating and cooling and critical 120V circuits, such as refrigerators and electronics. And because we package this as a solar heating/cooling system, the whole package qualifies for the Federal and State tax credits up to 60%, making it quite affordable. Finally, couple all of this with interest free loans from Santee Cooper, and you too can have the perfect storm.
THE FUTURE:
Earlier I mentioned, one of the greatest benefits of an AC coupling configuration is that it allows virtually any type of power generating device to be connected to the system, i.e. solar, wind, water, even gas or diesel powered generators.
So let’s add that gas powered generator, install a variable speed well pump, tweak a few more appliances in the home, and voila,
. . . . .your home is an island. And it’s not that hard to do anymore!
For more information, please contact:
Verlon Wulf or Steve Brakefield
Carolina Cool, Inc.
1294 Surfside Industrial Park
Surfside Beach, SC 29575 