Frequently Asked Questions

That’s fine. The Sunbank solar water heater is installed in such a way that you always have hot water; either as a pre-heater to your existing water heater or as a stand-alone system with a backup electric heating element installed in the Sunbank. And the Sunbank tank is very well insulated. If you use a lot of hot water at night then you will use the heat stored in the Sunbank and then the backup heater will kick in for any hot water consumed in excess of the amount stored.

No! Our system comes with a backup heating element so you can use it as your only water heater. If you do this, you will also need either our WiFi or hard wired controller. However, if you live in a cold climate, want more hot water capacity, or prefer to keep using gas as a backup, then you may want to install the Sunbank as a pre-heater to your conventional water heater.

It’s worth mentioning that when comparing a tankless system to a solar water heater, from an economical perspective there is almost no comparison. Tankless water heaters are relatively expensive to install, so while they may cost the same as a solar water heater they still burn gas or consume electricity and are 75% less efficient than a solar water heater.

While solar water heaters work a little bit differently than conventional electric or gas water heaters, the user experience of always having hot water is the same. Solar water heaters heat water slower than a conventional water heater, but they are heating the water constantly as long as the sun is shining and heat the water to higher temperatures. Slow and steady wins the race. By heating the water in the tank to high temps, like 160F, you have plenty of hot water as it is mixed down to 120F before it comes into the house using what is called a mixing valve.  And solar water heaters are always installed with a conventional backup, by either using the heating element in our tank or pre-heating a second tank, so that you always have hot water. 

The only maintenance needed is the replacement of the Magnesium anode which, depending on you water quality, is every 3-5 years. Although we recommend checking the anode after one year and basing future changes on how much of the anode remains. 

If you’re on a well, our advise is to install a whole house reverse osmosis filtration system before installing a Sunbank. High mineral content water causes corrosion and will shorten the life of the tank. Installing a filter will help your entire plumbing system last longer.

As far as we can tell, the disadvantages of a solar water heater are: higher upfront cost, harder to find an installer, and takes up space on the roof. The flipside of these are: lower operating cost (much lower net cost), perfect for a DIY installer, and frees up space in the garage or living area. We think the big advantages of lower cost and emissions way overshadow the disadvantages. 

Solar water heaters do work in the winter, although you typically get less heat from the sun in the winter since the days are shorter and the sunlight is less intense. Whereas in the summer (and most of spring and fall) you would expect to get 100% of your hot water from the sun, in the winter it is closer to 50%. That’s why solar water heaters have backup heating elements, that kick in to seamlessly provide hot water when the temperature falls below your set point. Of course this is climate dependent. We recommend our systems for installation in the southern half of the U.S. You would not expect 50% of your heat from the sun in the Alaskan winter!

Then you’ve found the right system. This system works perfectly as an off grid solar water heater. Our system requires 0 kWh of electricity to function and you can use the system whenever you have hot water. Or, if you want to always have hot water or a place to store your excess electricity production, we have a 120V element option that you can use for that.

A year round 95% solar solution is possible in places that do not experience a significant winter, like Florida, parts of the South, the Southwest, coastal California, etc. Even so, we recommend that the system be installed with a controller and auxiliary heater for those times when there is excess demand and/or a long period of rainy weather.

The only thing you truly need is a place to put the Sunbank. Roof mount or ground mount, with a ground mount often being easier, avoiding roof penetrations and shorten the plumbing run. Preferable you would have a at least 4 hours of direct sunlight per day and a relatively simple chase to your existing plumbing or existing water heater if pre-heating.

The Sunbank works even on cloudy days, but it won’t produce nearly as much heat as it does in full sun. 

The Sunbank collector and tank are both protected from freezing by their insulation. The tank has 55mm of high density polyurethane insulation. The collector tubes each have a heat pipe which contain a small bit of anti-freeze solution in it. That, combined with the fact that the tubes are evacuated means they are freeze protected to -35° below zero.

External plumbing is the most vulnerable point for freezing. The first point here is that we recommend PEX tubing instead of copper as PEX tubing does not burst when frozen. Your PEX must be well insulated and for prolonged freezing temperatures should include thermostatic heat tape in the insulation bundle or a re-circulation pump with a timer set to run at 5 minute intervals during the night in the winter. The added benefit of the re-circulation pump is that you can also use it to deliver hot water instantly your shower. In the case of a power outage where these freeze protections fail, we recommend a freeze protection valve be installed as a last line of defense.

The Sunbank is designed to heat a relatively small volume of water from ground water temperature to well over 120 degrees. There is a different technology designed to heat pools which heats a large volume of water only a few degree. This technology is “lower tech” than the Sunbank, not able to heat domestic water, and thus less expensive per BTU than a solar water heater. Feel free to contact us and we can tell you more about solar pool heaters.

It is optimal to have at least 6 hours of full sun per day or more, but the Sunbank will still make valuable heat in indirect sun and if it only has direct sunlight for, say, 4 hours. Any solar energy you absorb is free and contributes to your savings.