While long forays into the uses for photovoltaic power are fun and interesting, however it is no secret that heating water is by far the most cost effective way to use the sun’s energy. In dollar terms, PV power generation does not have a leg to stand on when compared to the solar heating of water. Best of all, heating water in this fashion can be accomplished by using materials we have sitting around our workshops. Even a garden hose sitting in the sun gets the water within it pretty hot on a spring day.
Two, 10 gallon passive water heating units that also act as storage tanks will be purchased from Jade mountain. I enjoy a somewhat long shower. This system will be used only from May through the first half of September in the Northeast portion of the United States. I presume that these tanks must be filled with a hose in the morning and then heat up throughout the day. According to the specifications, water mat be heated to 110 Fahrenheit when the outside temperature is 70 degrees. My guess is that the water in the heaters will become even hotter.
A small pump will be connected using some type of tubing to the tanks and brought to the outdoor shower we use. Almost all of the hot water usage is from showering since we do not have a dishwasher. The pump will probably be in the 4 gallon per minute range and I plan to power it from a small photovoltaic panel and a battery.
The Feeding Problem
The simplest thing for us to attempt to do is build another shower that is connected to our solar tanks and has a feed from the garden hose for cold water to be mixed with the hot. Before falling back on this plan B, we are going to attempt to supplant the normal hot water feed to the outdoor shower with the solar hot water feed. Every house’s plumbing contains water under pressure. By cutting the normal hot water feed to the shower, we can hook up the solar hot water feed in its place. Thankfully, there is already a knob to turn off the house’s hot water feed. All that needs to be done is to find a way to feed the solar hot water into the shower’s hot water feedline.
The Next Step
Ideally, one would want to use the system to satisfy all of the house’s hot water requirements. This requires linking the solar water heating system to the existing hot water tank which is pressurized anywhere from 20 to 50 PSI. Heating water and then delivering this heated water the hot water tank would reduce the amount of time the water tank would need to be running to get the water within it up to a comfortable temperature.