Evacuated Tube Solar Collectors

The evacuated tube collector is made up of three main components: an evacuated glass tube with a selective coating that optimizes absorption, aluminum fins that transfer the heat inside the tube to a copper heat pipe, and a heat pipe which transfers this heat to the water.

Evacuated Tube

One of the components that make the Sunbank so special is its evacuated tube collector. In a vacuum there is no heat transfer which means that the vacuum tube is almost perfectly insulated.

Like an extreme version of a Thermos that keeps coffee hot, the Sunbank evacuated tubes preserve the 400 degree temperatures inside the tube while the outside remains cool to the touch. This allows that heat to be transferred to the water tank instead of being wasted. And because of this insulation the outside air temperature does not negatively affect the high heat transfer inside the tubes.

There is no water in the evacuated tubes. This allows for excellent winter performance by transferring the heat into the tank with the copper heat pipe without any freeze concern. Also, if one tube is broken, the system continues to work without the tank draining.

The fact that the collector is a tube with a circular shape, as opposed to a flat plate collector, means that the sun is always hitting the collector at a 90 degree angle throughout the day. This optimizes absorption with passive tracking.

The Sunbank collectors are made more efficient by the three target selective coating of Al-N/Al. These three coatings create an anti-reflection layer, a transference layer, and an anti-infrared reflection layer. The evacuated tube is made of high-strength borosilicate glass, a glass with high chemical and thermal shock resistance that can withstand 25mm hail stones.

Heat Pipes

Heat pipes act like a low-resistance thermal conductor. Due to their thermal-physical properties, their heat transfer rate is thousands of times greater than the best solid heat conductor of the same dimensions. The heat pipe transfers the high heat generated by the evacuated tube into a manifold that heats the water in the insulated tank.

Heat pipes are more common than most people realize. In fact, you are using a heat pipe in order to view this webpage. Heat pipes are one of the most efficient ways to transfer heat, and so your computer uses heat pipes to take away the heat from the processor so that your computer does not overheat.

The Sunbank heat pipe is made of high quality copper that conducts energy extremely well. Inside the sealed heat pipe is a proprietary solution. When the temperature inside of the evacuated tube reaches 80 degrees Fahrenheit, this solution vaporizes and flows to the top of the heat pipe. At the top of the heat pipe is a condenser bulb, which fits into the manifold. It is here that the vapor releases its immense energy, condenses into a liquid and falls to the bottom of the heat pipe to start the process over again. This continuous cycle is what heats the water in the Sunbank.

Aluminum Fin

The aluminum fins holds the heat pipe in place and conducts the heat from the inside of the glass tube into the heat pipe. This heat is then transferred into the water tank which acts as a “battery” that is charged up ready to use when you are.

    EXCELLENT  
  16 reviews on
 
 
         
   nic maier 
 
 
 
   I don't write reviews but I have to tell others about James from Sunbank! We got an 80 gallon solar water heater and installed it ourselves. It works very well in Southern California. The installation was a little challenging for us, but James helped every step of the way and was even available to give us advice a full year after we had purchased the unit. He was always quick to respond with a thorough and helpful answer! I wish all businesses were run like Sunbank with people like James!
  
 
 
       
   Bob Billings 
 
 
 
   James, thanks for your continued support.  Our 40 gallon Sunbank water heater is the best. Installed in October of 2021 and we would not trade it. Our life off-grid has worked out well. Bob Billings
  
 
 
       
   Jonathan Bishop 
 
 
 
   My only regret is not getting the Sunbank sooner! I installed the 40 gallon system which has been perfect for 3 people. It has a 1500 watt element to heat the tank when the sun isn't shining and because of the low power demand, we are able to run it completely off-grid. James also took time to answer any questions I had and has been excellent to work with!
  
 
 
       
   Robert Thorlin 
 
 
 
   James and the team at Sunbank are exceptionally knowledgeable and willing to help.  Pre-sale and post-sale support was wonderful, even to the point of shipping a bunch of extra T-bolts I needed for my unique installation, bolts and shipping all at their cost.

I would bot hesitate to work with them again on anything... 10 stars if I could...

Mike
  
 
 
       
   Elsa Hennings 
 
 
 
   Living in the Mojave desert, I've wanted to "go solar" for our home's energy needs for a long time (I like free stuff). We put in a solar electric system in 2004, which has long since paid for itself, and bought a plug-in hybrid car to use our "free gas" several years ago.  I finally decided to heat our water with the sun, and after looking at a number of systems, I chose SunBank Solar based on it having no moving parts (I don't like to fix stuff). I mounted it on the ground since we have no shading on the other side of the wall from our old electric water heater, which made the plumbing pretty simple. For overheating protection in the desert, I painted half of each heating tube with reflective silver paint as James recommended (see photo on right), so when we leave on vacation I just rotate each tube to prevent heat absorption, turning the system off. The instructions provided, along with some how-to videos on youtube for using pex tubing, allowed me to get it all put together with no prior plumbing experience.  James was an invaluable resource when I had questions, which was often!  The system has now been running for over a month, quietly generating all the hot water we need!  I highly recommend not only the system but the company for the high quality materials and excellent product support!
  
 
 
       
   debra covey 
 
 
 
   Installed the Sunbank 40 water heater 12/2019. We didn’t install the controller until 8/2020 in case we needed it in the coming winter, but still haven’t needed supplemental heat in south Florida as of 4/2021.  Love this thing! Works great for the 2 of us in our small (1000 sq ft) home.  So glad we installed it.  Company was very responsive to all questions prior to ordering through install.  Highly recommend!
  
 
 
       
   Jim Feldhan 
 
 
 
   I rarely write reviews; however, I am very happy and impressed with the Sunbank solar hot water heater. It appears to be made from top quality material. I was replacing a Solarhart which was not a stainless steel tank and the heat exchanger developed a leak. I started with a 40-gallon system and installed it myself. I’m very handy with DIY projects.
The Instructions online were clear, and James was very helpful with any of the questions I had.
Being in Phoenix I thought a 40-gallon system would be enough. Once Witter arrived, I realized that I use more hot water than I thought and wanted to have 100% solar hot water. Thus, I installed a second 40-gallon system to boost my capacity to 80. I also install a couple of radiators to heat the master bath and home office allowing me to heater those room in the fall, winter, and spring with excess hot water.
In summary, I am very happy and give Sunbank 5 stars for quality and service.
  
 
 
       
   Timothy Clayton 
 
 
 
   I installed the Sunbank and the water temp went from 50F to 101F in 4 hours the 1st day.  By the 3rd day I was up to 160F.  It only loses approx 5 degrees overnight.  It is awesome!  James at Sunbank is one of the best support guys I've dealt with.  Definitely recommend buying this for solar hot water.
  
 
 
       
   Cuyler Smith 
 
 
 
   Our family purchased a 40 Gallon Sunbank Solar Water Heater just over a year ago and we are VERY pleased with its performance, ease of installation, and energy savings!  We have it installed on top of our spring house roof, located about 125 ft. away from our house.  When combined with the Federal Tax Credit and the savings associated with the solar offset of electrical usage for heating water, this Sunbank system quickly pays for itself and is a great investment.  I was able to install the system on my own and it has performed flawlessly during its first year of use.  James at Sunbank Solar has been more than helpful in responding to any questions I have, even after the initial purchase, which says a lot!  I would recommend the Sunbank Solar Water Heater to anyone wanting to save money and reduce our environmental impact!
  
 
 
       
   tutti hacking 
 
 
 
   I recently installed two 40 gallon Sunbank solar water heaters - one on my garage and one on my ADU. They have been awesome! Water is super hot and now I don't have any qualms washing my laundry with warm, solar heated water! I have wanted a Sunbank system for almost four years now, and James has patiently helped me through the process. I used my local solar panel installer to get the job done. Took 3 days to fully install (I did need some reinforcement for 2x4 rafters) and inspection was quick and easy. James steered me to a great structural engineer to get what I needed for City Planning. It feels great to have gotten rid of my natural (fracked) gas water heaters! And the 30% tax credit, along with the California Solar Initiative rebate, really makes it affordable.
  
 
 
  
 
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