All our panels are meant to connect directly to the water heater / solar tank. This eliminates the need for expensive heat exchangers or special solar tanks that have built in coils.
In this document we present some of the basic ways to connect a standard water heater (gas or electric) to a set of solar panels. If you have purchased a "Solar Storage Tank" the manufacturer will have specific connection instructions, and the following does not apply.
The information herein is intended to introduce the different connection methods only and is not meant to give advice on plumbing and is always superseded by your local plumbing codes.
You can use a single (existing) water heater or two separate ones. We describe the three connection schemes for single tanks first and then present how to connect dual tanks.
A dual tank system harvests solar heat far more effectively, but you have to purchase an additional heater and have room to install it next to the main unit. The two units in a dual tank system can be of different size.
Bottom Connection through "Boiler Drain"
This type of connection is very simple and reliable. It requires the installer to remove an existing boiler drain, install a bottom feed connector and re-install the boiler drain into the bottom feed connector. The advantage of this hookup is that no check valve is needed, and the existing plumbing to the house is not disturbed.
Overall View: the existing connections to the house are not changed
Closeup of Bottom Feed Connection
Detailed instructions on installing a "bottom feed connector" through the boiler drain port are here .
Some water heaters do not have a boiler drain, or sometimes the boiler drain valve cannot be removed without damaging the water heater. In these cases the alternative connection schemes must be used.
This type of connection requires 2 tees to be introduced into the cold and hot connecting pipes on top of the tank, plus it requires at least one check valve with very low flow resistance. The advantage of this connection scheme is that the boiler drain of the water heater need not be disturbed.
Overall view of top connections
For this type of connection a check valve in the hot water line from the panels is necessary to prevent hot water from the tank from being cooled in the panels at night. Also it is advisable to include a "U" in the hot water piping as shown.
Closeup of top connections
On very few smaller water heaters there is no boiler drain and the connecting openings are on the side of the unit. On these a "side connection" is required.
Very few water heaters do not have a boiler drain and also do not have the hot and cold connection on top of the unit. These have connections on the side, the cold near the bottom, and the hot near the top. Connecting to this type of unit is very similar to the top connection case. Please note that the water heater usually does not come with an installed drain valve, so it has to be added as part of connecting the system.
Dual Tank Connection
In a dual tank installation the solar water heater is connected to one tank which is not used as a gas or electric heater. The second tank is the unit which functions as a normal gas or electric unit. The input water enters the first unit and is heated by the sun. Then it enters the second tank. If the solar heated water is hot enough the second tank simply passes the water through. If on the other hand the solar heated water is not up to the selected temperature (night or cloudy periods) the second tank heats it to the desired temperature.
The first tank can be connected to the solar tank in any of the three aforementioned ways. The only difference is that the HOT Water Out port is connected to the Cold Water In port of the second tank. Then the Hot Water Out port of the second tank is connected to the House, RV or Boat's hot water lines.
The temperature setting on the second tank is the temperature of the water that comes from the system.