Solar Collector

On this episode of what I learned at Highland Orchards, I want to talk about solar panels. Although some of the workers joke that the business is killing the environment since we burn wood stoves and have a lot of fuel guzzling heavy equipment, we do in fact have a small solar array to heat water.

Most often when you think about or notice solar panels, they are made to produce electricity. However, the ones we have use the suns radiant thermal energy to heat water for the bakery and convenience store. Unfortunately, last summer it stopped working and I was tasked to fix it.

The system has three major parts. The most obvious is the solar array. The solar panels sit on a roof, sloped to the south for maximum sunlight. These panels are simply a snake of black pipes that go through a glass faced box. The pipes go from one end of the box to the other, turn around and come back, repeated until the box is full. The point of this is to provide maximum surface area for the sun to reach the pipes. The next important part of the system is a pump. The pump drives the water through the array and to the final major piece. The heat exchanger transfers heat energy from the water warmed by the array to the supply of domestic water destined for the conventional water heater. The reason for this is the water that goes through the array is treated with nontoxic antifreeze, and is unfavorable for consumption (the antifreeze water is in a closed loop).  The domestic water goes into the heat exchanger at a relatively constant 55 degrees (from a well) and leaves at a higher temperature, say 80 degrees on a reasonably warm day. The water then goes to the conventional domestic water heater, which brings the water up to the desired temperature. Thus, the solar collector makes the water heater’s job easier, saving energy.

Although this may sound simple, there are several complicating factors that make operation less robust. The first time I had to repair the system, I replaced the control panel. This component turns the pump on and off depending on the temperature of the panels. If it is really cold (like right now) the pump won’t run because it would actually cool the water. The next problem I fixed was letting air out of the line. Air is less dense than water and therefore, when water entered the system, it rose to the roof. This air pocket grew in size over time and eventually prevented water from flowing through the panels, as it formed something called an airlock. It wasn’t until after replacing a few sections of pipe and adding a new pump we determined that the airlock was the issue. To solve the problem, we open a valve on the roof and let the air out. This works much like a “spit valve” for any brass instrument players out there

One thought on “Solar Collector

  1. Yixuan Wang

    Wow, that was really detailed! I am working on a Renewable Energy blog, and while I have not looked into solar energy, our blog just made everything so much more interesting! It’s really cool that you know how to fix the solar panels! While I knew that there was a thing called a solar panel, I never knew what exactly was inside it until now!

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