Solar Hot Water System

Our Solar System

Over two weekends in November 2010 we installed an Apricus solar hot water system on our house with the help of volunteers from SEAREI and David Glover of Glover Plumbing.

We are using a Resol BS differential temperature controller with a Datalogger DL2 linking it to our home network, where some scripts add the temperatures into a database and creates these graphs.

The graph below shows the temperatures through a 24 hour period. The red line is the solar tube temperatures on the roof. The green line is the temperature in the bottom of the hot water tank - dips in the green line are us using hot water in the house. When the collector is hotter than the tank the hot glycol circulates, warming our hot water and saving us money. The dark blue line is the top of the tank - when it's hotter than light blue line (the boiler fired tank) the second pump comes on and we're saving even more money :D

Graph of boiler return temperatures

Daily Graph, Weekly Graph, Monthly Graph, Annual Graph

This is where the geekiness begins. This is the difference in the temperatures of the collector and the water tank plotted against the pump speed.

Graph of boiler return temperatures

Daily Graph, Weekly Graph,

Pump Speeds

The Resol controller adjusts the pump speed to maximize transfer of heat to the tank.

Collector Pump

This is the pump for the solar loop which runs from the roof top collector to the solar tank heat exchanger.

Circulator Pump

When the solar tank is 10°F warmer than the boiler tank this pump circulates the warming water.

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