Roth FAQ Solar Flat Collector, Vacuum Tube Collector, Pool Collector and Solar General

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FAQ - Solar

What is the Max temperature fluids can reach in the collectors?
The maximum expected fluid temperature varies depending on region. The panels are rated to a max temperature of 357 degrees F. We require the use of our Roth Solar fluid that contains additives to allow us to operate at these high temperatures.
What is the ability to withstand snow load and how to clear snow off the Collectors?

When in regions that experience heavy snow loads it is required that we angle the panels to 40 degree or higher. This allows the snow to slide off the panel.

Is the polycarbonate case brittle especially in cold temperatures?
The Polycarbonate body will remain stable under extreme climatic conditions. The Panel will not distort at high temperature, and will not become brittle under low temperature. Physical properties will remain unchanged in the temperature range of -40F to 240F making it the perfect material for this application.
What is the weight of the collector?
The weight of the Heliostar 252 is 98.4 lbs. dry. 100 lbs wet.
What is the flow pattern in the collector?
The internal copper pipes are arranged in a "Harp" configuration.There is no dedicated supply or return it depends on the piping configuration.
How many collectors can be connected together?
The maximum number of collectors in series is 5. You may connect multiple groups of five in parallel to a common header with a reverse return piping arrangement. It is really dependant on the capacity of your pump station.
What type of fluid is in the collector?
Heliostar solar fluid is an antifreeze substance composed of propylene glycol (94 %) and protective inhibitors (6 %). Roth Heliostar solar fluid is suitable as a heat transfer medium in solar installations as well as in heating and cooling systems. When diluted with water, Roth Heliostar solar fluid has a very high heat transfer capacity and at the same time a favorable
viscosity, even at low temperatures. Special inhibitors provide solar energy systems in mixed installations (dissimilar metals) with reliable protection against corrosion. Roth Heliostar solar fluid and water are compatible with commercially available elastomers such as EPDM rubber, PE and PP.
What is the mounting angle of the collector?
The mounting angle of the collector is typically the latitude of the region it is being installed in. This allows for the most efficient angle maximizing solar energy over the year.
How do I drain the collector?
The Heliostar 252 is not designed for a DrainDown or DrainBack system. It is designed as a closed loop system using our Solar Fluid. If it requires draining it can be accomplished by opening the fittings on the roof, draining the solar station, and using air pressure to remove the remaining fluid.
What is the pressure relief?
The Roth Solar station operates at 40 psi. Our pressure relief valve will release at 80 psi.
Why the need for a thermal expansion tank?
As water is heated it will expand. It is necessary to have an area for this expansion to be absorbed.
What type of glass is used and how durable is it?
We use low Iron Oxide safety glass. It is very durable.
What is the payback period?
The US Department of Energy defines a systems payback as the annual fuel bill savings divided by the capital cost. This can be inaccurate. It is more accurate to factor in future energy increases, take into account inflation, and review the savings in equipment replacement. Calculating correctly most thermal hot water systems offer a pay back of between 6 and 15 years, depending on the fossil fuel savings, the future cost of fuel, cost of living increase and the system efficiency and capacity. Add the possibility of substantial federal, state and local government programs, coupled with current utility company programs and the payback can and will be substantial.
What type of mounting is available?
Roth Industries offers 3 types of mounting in North America, the roof mounted system typically using the existing angle or pitch of the roof. The flat roof or Ground mounted rack system, with a fixed 45 degree angle. The adjustable rack system that allows up to a 50 degree angle and is designed to be used on a pitched roof.
What are the wind loads?
Our Rack systems and panels can effectively withstand a 90 mph wind load.
What is the Btu output of a collector?
The BTU output of the collector varies depending on geographic location, ambient temperature, and seasonal position of the sun.An average number is approximately 6000 Btu/hr in the Midwest. It will be far less in January and higher in summer.
Do I need a storage tank, and if so what size?
Yes it is necessary to install a storage tank designed to be connected to a solar system. It is all in the size of the tank, the larger percentage of storage the more efficient your system will operate. A minimum of 80 gallons to 120 gallons is typical.
How does my hot water heater connect to the system?
It is better to abandon your existing tank for one designed for the solar application. IIf necessary it can be used with the Solar tank. We have the necessary diagrams available to facilitate this application.
What happens when my hot water is fully heated? Where does the heat go?
Depending on the design, this should not occur often. We design the systems determining , the amount of use, the amount of storage, the amount of energy available from the sun for the region the installation is located. With the use of the Roth solar pump station and our Roth Controller, the pump modulates flow based on input values from the sensors located in the system. When the system temperature is met the pump still circulates a small amount of fluid to prevent stagnation. Remember the system is capable of 357 degree F temperatures. If necessary in high solar areas it may become necessary to have the extra energy transferred to another use like a swimming pool or alternate storage.
How many of these do I need to heat my house?
Heating a home with solar energy alone is possible, but many modifications would be required. Solar energy usually supplements a traditional heating system.
What keeps snow from building up under my collectors and creating ice dams/back up of melt water/new sheetrock ceilings in my house?
The Roth Heliostar Roof Anchor system allows for 4" of clearance from the roof. This elevation as well as the anchor points help to avoid issues with snow and ice.
Can hot water from my storage buffer be rejected to the solar collector to aid in removing snow/ice from the collector? Can this be automated?
Yes, it is a automated operation. The controls work on differential temperatures if the panel is warmer than the stored water the pump is energized. When cooler, it shuts off.
What can I expect the annual operating costs of this system to be?
The cost of running the pump is similar to that of a 100W light bulb. Less than a dollar a day.
What is the expected lifespan of this system? Should I replace my roof before installing?
The average lifespan of a Roth solar system is 25 years. IIt would be wise to have a roofing contractor evaluate your roof prior to installation.
What kinds of roof materials/designs can this system be installed on?
Roth Solar Panels can be installed on all types of roofs. Our basic system is designed for asphalt shingles, but we have anchoring systems available for most roofing materials in North America.
These new vacuum tube systems are cool looking, why is yours better?
The Roth R1 vacuum tube solar collectors are light, easy-to-install and extremely high efficient. The R1 is equipped with CPC reflectors which provide optimal sunlight reflection to the glass absorber at any angle.The Roth R1 reflectors are made of corrosion resistant aluminum mirrors with acrylic seals - a combination of materials resulting in significant weather resistance. The extraordinary performance capability makes the Roth R1 exceptional, allowing for domestic hot water generation even during times of little sun (such as in the winter time).
Can these be mounted horizontally vs vertical for installation sites with odd roof shapes?
Yes, the Roth Heliostar 252 can be mounted vertical and horizontally.
Does the panel install with the fittings at the top or bottom?
The Roth Heliostar 252 panel connections in vertical configuration are at the top of the panel. The connections in a horizontal configuration are on the side.
Should I plan on a backup DWH system in addition to my solar?
Most solar DHW systems will require a supplemental heat source, when the weather conditions or load requirements exceed the solar systems capacity.






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