The Concept of Gain When Improving Your Home with Solar
You have wanted to go solar, but you’re not excited about the idea of putting panels on your roof. Don’t worry, there are other ways; you just need to understand the concept of solar gain. Solar gain (also known as solar heat gain or passive solar gain) refers to the increase in temperature in a space, object or structure that results from solar radiation. The amount of solar gain depends on the strength of the sun, and the ability of any intervening material to transmit or resist the radiation.
You’re saying all I want to do is gain some heat and save some expenses. So I’ll cut to the chase, gain refers to how you generate heat for your home without solar panels. You can think of it as gaining heat by manipulating the power of the sun. There are three categories of gain: direct gain, indirect gain and isolated gain.
So lets look at, what we are really talking about here?
Objects struck by sunlight absorb the short-wave radiation from the sun and re-radiate the heat at longer infrared wavelengths. Where there is glass (which is more transparent to the shorter wavelengths than the longer ones) between the sun and the objects the sun is hitting, there can be an increase in temperature, i.e. solar gain, when the sun is shining. This is called the greenhouse effect, due to the solar gain that is experienced behind the glass of a greenhouse. It has also become well known in the context of global warming.
Direct gain is the simplest passive solar home design technique. Sunlight enters the house through the aperture (collector)—usually south-facing windows with a glazing material made of transparent or translucent glass. The sunlight then strikes masonry floors and/or walls, which absorb and store the solar heat. The surfaces of these masonry floors and walls are typically a dark color because dark colors usually absorb more heat than light colors. At night, as the room cools, the heat stored in the thermal mass convects and radiates into the room. The disadvantage is it only works during the day and for a couple of hours afterwards. The advantage of direct gain is it is fairly easy to implement.
Indirect gain is a bit more complicated. It refers to the idea of using a structure between the exterior and interior of the house to store heat produced by exposure to sunlight. The basic idea is to get more heat production for a longer period of time. Indirect gain is typically accomplished by building a thermal wall out of masonry, known as a Trombe Wall, as the south facing wall of your home, or a part of it. The wall is built out of a material that absorbs heat such as concrete or brick and then has glass placed over it. Put another way, the south wall is a window with a brick wall inside it. The wall materials suck up the heat of the sun and store it. This heat is then radiated when you need it by opening vents in the wall.
One of the most interesting indirect gain passive solar building types is the water wall. Here the sun’s rays are collected by a water storage mass, then converted into heat and distributed by convection and radiation to the living space. The water wall involves the same principles as the mass wall, but employs a different storage material and different methods of containing that material. Water walls are slightly more efficient than a masonry wall. However, a masonry wall is preferred because masonry is more permanent and will release the heat in a delayed cycle.
The advantage of indirect gain is you get longer, more controlled heating.
Isolated gain is a simple concept. Have you ever used a greenhouse to grow flowers or tomatoes or something? Isolated gain works just like a greenhouse, except you are providing heat to yourself instead of plants. Essentially, you build a self-contained glass structure on the south side of your home which is also well insulated. The structure heats up in the sun during the day to very high temperatures. When you need heat, you just turn on a fan, which moves it into the house through venting you’ve installed.
The beauty of any of these systems is they are fairly simple concepts to understand. If solar panels don’t appeal to you, just go for some gain.
A Key In Solar Hot Water Panels – Efficiency
In the UK it is reported that the average domestic heating bills have increased by 125% over the past five years and that energy prices will likely continue rise. And there is little difference here in North America either. This is very difficult for most people. As these costs rise, the use of the Sun’s solar energy becomes more and more of an option people are considering. Solar technology is advancing more and more and with the government offering grants for Solar panels, solar powered houses are becoming more affordable.
While solar energy is most often associated with the production of electricity, heating is also a major platform. While heating hot water isn’t particularly difficult, the efficiency in doing so is a real key to savings with your system.
Solar panel hot water systems have historically been very inefficient at converting the suns limitless power into usable energy. With improving technology, efficiency has improved to the point where most panel systems can easily produce enough energy to heat water for the home and pool. Research shows that solar hot water heating systems can deliver up to 70% of the hot water requirements for an average household but there are efficient and inefficient ways to go about this process.
To save wear and tear on your panels, you need to consider a flow control system. Older panel systems tended to take a long time to heat up fluid because water more or less randomly circulated through the system. This was very inefficient because the panels are forced to heat up a much larger quantity of water than you actually need. This results in wear and tear, not to mention lengthy waits for hot water.
A control flow system corrects this efficiency problem by reducing the amount of water that must be heated.
How it works:
Most are designed to work on temperature differential strategies. They work by using two sensors. The first is located close to the panels being used to heat the water or liquid substitute. The second is located on or close to the liquid return valve into the panel system. Put in practical terms, one sensor measures the temperature of liquid set to leave the panel while the other measures the temperature of liquid coming into the panel.
When the sun comes up, the solar panels start producing heat. A circulation pump draws the water from your reservoir and pushes it through the solar panel heat exchanger and returns it back to its reservoir. The circulation pump will only switch on if the solar controller instructs it to do so. The instruction will only happen if the advanced controller detects that the solar panel is 10 deg.C hotter than the reservoir water temperature. This process is continued throughout the day, until the sun goes down and the pump automatically switches off. The reservoir thermostat temperature can be adjusted using the advanced controller as well as the element run times as a back up. This ensures that on days where there are absolutely no UV rays around, you will still have warm water. Once the return valve sensor notes the temperature of the returning water is within a particular range of the liquid in the panel system, the pump is shut off. This process allows for faster heating times, more efficiency and less wasted energy.
The benefits of using solar energy for hot water heating are immense. For one the energy source comes for free and investing in solar energy is an investment in the future of the environment and should add to the resale value of your property. 
By using solar energy to heat domestic hot water you will be helping to reduce our dependence on fossil fuels while at the same time improving the energy efficiency, and potentially the value of your home. Solar can be a cost-effective solution for you as well. Just keep in mind that flow systems are a must if you are pursuing solar water heating.
Want to learn more? One of the best and most popular guides is GreenDIYenergy.