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Sunbank SR609C Solar Controller

by Sunbank
Original price $249.00 - Original price $249.00
Original price
$249.00 - $249.00
Current price $249.00
in stock, ready to be shipped

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Sunbank SR609C Solar Controller


120-240 volt solar controller is a thermostat that displays the temperature inside the Sunbank tank and powers the 240V (40G and 80G) auxiliary heating element. The controller comes with 150 ft sensor wire so that it can be mounted inside the house while monitoring the temperature inside the solar water heater. This controller also has a relay through which a pump can be powered to do both overheat protection and freeze protection. See the Sunbank Recirculation Valve and Pump listing for more information about this.

Requires a dedicated circuit if also powering the element.

Product Specifications

Sunbank SR609C Solar Controller Product Specifications

Weight 5 lbs
Dimensions 12 × 7 × 3 in


Product Manual


Product Warranty

SunBank Product Warranty

We want you to enjoy free hot water for a long time and that is why we offer a 10 Year Warranty for manufacturer’s defects on our evacuated tube collectors and a 1 year warranty on all other components of the system.

We understand that going solar is a big investment and we want to work with you to make sure that you are happy with your investment, including a reduced price for replacement components that are out of warranty. Solar water heaters experience incredibly harsh and varying conditions. The combination of extremely hot water, pressure changes, mineral content, and chemicals are things that wreak havoc on a water heater. And these conditions vary in every municipality and well water system across the country. This is why every Sunbank tank comes with a magnesium anode and we recommend that it is checked one year after installation and that future changes are based on how much of the anode remains after one year. For more information about sacrificial anodes read this.

Solar water heaters, with their widely varying temperatures, also experience much more pressure fluctuation than conventional water heaters. Because of this, we recommend that you install an expansion tank when installing your Sunbank. Especially if you also have a check valve or “backflow preventer” installed in your system.

We make the Sunbank out of the best components that we can. That said, nothing lasts forever. We look forward to working with you when your Sunbank is working great. And if it isn’t, we looking forward to working with you to make it better and to help you to continue to harvest that free energy from the sun.

Product FAQs

Do I need to keep my conventional water heater?

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.

Can I use this with a tankless or on demand water heater?

Absolutely! That is a very efficient installation scenario because you avoid the standby losses of a conventional tank water heater. Most all modern tankless water heaters accept pre-heated water, or are “solar ready,” but check with the manufacturer before installation so that it doesn’t void your tankless water heater warranty. They can be sensitive systems, and sometimes manufacturers will want to make sure your water is not too hard, also, in order to honor their warranty.
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.

What if I'm on well water or have hard water?

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.

Can I put in a second, longer magnesium anode?

Yes! If you have high mineral content water, or just want to protect your tank and not change your anode as frequently, this is a good idea. For our newer systems that have the side port on the bottom of the side of the tank (not the middle), you can use a 3/4″ brass coupling installed on the cold side port to install a 42″ rigid anode. For our older models or our newer models, you can install a flexible 42″ anode, also available at most hardware stores.

What if I'm off grid?

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.

What if I use a lot of hot water at night?

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.

What happens to the temperature when I take a shower?

The Sunbank typically stays in the 100F-160F temperature range. Your Sunbank may be at 140 degrees when you take a 10 minute shower at 2 gallons per minute. That means you have used 20 gallons of hot water thus introducing 20 gallons of 60 degree ground water into your Sunbank tank. For an 80 gallon tank that means you have used 1/4 of the heat which would drop the temperature of the tank by 20 degrees (140-60 X .25) to 120F. In reality you would be using less than 2 GPM of hot water because you would mix down 140 degree water to 120 so that it doesn’t scald you. You would actually use 15% less hot water or 1.71gpm (140/120 X 2) and therefore be left with 123F in the tank. Any water temperature over ground water temperature means gas or electricity savings. And when your Sunbank is over your backup temperature set point you are not using any fossil fuel to heat that water.
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Talk to one of our trusted experts today! Our dedicated customer support team is here to provide any assistance that you have. Feel free to place an order over the phone (415) 481-4075 or send us your inquiry via chat.