History of Solar Water Heating

In our last blog post we told the Sunbank story; why and how we started down this road. In this post we hope to answer a pressing question for anyone looking into solar – why are photovoltaic panels, herein referred to as PV, so popular and solar water heating (or solar thermal) so much less well known?

The story is a complicated one – one of technological wins and losses, of partisan politics, and industry cohesion. Before I go into the history, let’s first differentiate between solar PV and solar thermal. And before I can differentiate between solar thermal and PV I should first differentiate between the various types of solar thermal. Unlike the PV industry, in which most of the technology is more or less the same, thermal is much more diverse of an industry.

Bear with me for a second because this is going to get a little wonky. There are two main variables that differentiate solar thermal systems. Active vs. passive and direct vs indirect.

An active system utilizes a pump to transfer heat between a collector and tank whereas a passive system uses natural convection.
A direct system has potable water go through the collector whereas an indirect system has a water/glycol mixture (lower freezing temperature) go through the collector.

These things are important, because solar thermal systems must be protected from freezing and overheating – and there are various methods for achieving this.

The Sunbank doesn’t fit into any of these categories. Instead, it borrows the best attributes from each. It most closely resembles the top right box, except instead of having potable water in the collectors it only has it in the tank. This makes it more freeze tolerant without the need for pumps that consume electricity and eventually break over time. There are other valid types of solar water heaters, especially for very cold climates or warm climates with intermittent use, but after a lot of research we decided on the Sunbank type system because it is more affordable, simpler to install, and has less maintenance issues than the other types of systems. So, from here on out when we say solar water heater we are referring to the Sunbank.

Now, let’s compare solar thermal and solar PV. PV creates electricity, is 15% efficient, and typically costs $20,000 – $30,000 for a residential installation. Solar water heating, on the other hand, offsets the use of gas or electricity by heating water. It can be up to 90% efficient and the typical residential system costs less than $5,000. Looking at this table you can see that the Sunbank is less expensive and more efficient, so why isn’t it more common than PV?

First, let’s go back in time. Solar thermal has been around for millennia in the sense that we’ve been using the sun to heat things since we first existed. The first commercial solar water heater dates back to the 1896 when Clarence Kemp of Baltimore, Maryland created what he referred to as the “Climax” solar water heater. The design since improved in iterations to account for the two main issues with solar water heaters: freeze protection and overheat protection. By the 1920s solar water heaters were ubiquitous throughout Florida and Southern California. Interest spiked in the 1960s and again after the 1973 Oil Embargo. Jimmy Carter put solar PV and solar water heaters on the White House and the industry looked on its way to being a strong contributor to the country’s energy portfolio.

Meanwhile, solar water heating was taking off in other parts of the world. In Israel, for example, solar water heaters became popular as there was a fuel shortage in the new country in the 1950s. In the 1970s the energy crisis brought with it a law passed by the Israeli congress, the Knesset, that all new homes (except high rises without adequate roof space) must have solar water heaters. Now there are solar water heaters on 85% of Israeli homes which saves the country an estimated 2 million barrels of oil per year.

What do these historic vignettes illustrate? First, that the success of solar water heating is directly tied to the price of energy. Cheap fossil fuels inhibit innovation and adoption, whereas fuel shortages and high prices increase these rates. In these cases, the energy crisis spurred installations of solar water heaters. Secondly, government incentives and mandates (or lack thereof) are an effective motivating force for people to make a switch to alternative energy that they would otherwise ignore for an alternative energy technology to experience high rates of adoption, a government incentive or mandate is highly beneficial.

For more information on government incentives for switching to alternative energy click here: www.dsireusa.org
Have questions about Solar Thermal and how you can join the movement? Tweet us @SunbankSolar or contact us today!

    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.
  
 
 
  
 
  Load more