To avoid confusion between hot and cold water in the same pipe, a check valve can be installed on the respective hot water pipes. When using water in this pipe, water may overflow. In case of reverse water pressure, the water will not flow back due to the check valve. There is no interaction between the two hot water sources.
The following picture can explain the direction of water flow
The easiest way is to bury a hot water pipe directly in the kitchen and bathroom. If the decoration is completed, please refer to the following treatment
1. The water outlet of the bathroom electric water heater is connected to the solar water outlet, but a check valve needs to be added. The direction of the check valve is from electric water heater to solar energy.
2. Install a one-way valve on the main pipe of the solar sewer pipe.The one-way valve is from top to bottom. However, most solar water heaters have an incoming and outgoing water line. This solution is therefore not feasible.
It's best to lay a new pipe like I said, otherwise the hot water from the electric water heater won't necessarily flow where.
As shown in the picture, install a check valve in the circle and install a check valve in the middle where the two triangles are connected.