Despite all the advances of modern technology, the best solar fluid for use in a solar thermal installation is water. It retains and transfers heat better than any other liquid in the world. However, it has one major drawback: it freezes easily.
The industry standard for solar fluid is a mix of propylene glycol and water. It's non-toxic, biodegradable and relatively stable. However, you should always mix as much water as possible with your choice of glycol product, as simple water is the ideal solar fluid.
As everyone knows, just about everything expands when it gets hotter. With gases, they can exist in the same space and build up pressure, but liquids have difficulty doing that – when a liquid expands, it needs more space.
When you first set foot in the renewable energy arena, it can look daunting: different technologies, different approaches, net-zero, net-positive, PV arrays, solar thermal, geothermal, wind power... it's a big subject and can be confusing. So where should you start?
There are some things you can do to save energy and money before you install even the simplest renewable energy system. The three simple steps are to reduce losses, increase efficiency and reduce consumption.
Integral collector storage (ICS) solar hot water systems are the cheapest, simplest installations. Consequently, they have more limitations than other, more robust setups but are a lot easier to set up and maintain. They are open, passive systems.
It doesn't matter whether you're looking at renewable energy from the point of view of saving money or saving the environment: solar thermal systems are a great way to take your first steps. As it happens, preserving the environment and reducing your bills often go hand in hand, although it may not be immediately apparent when you look at the cost of installing new systems!
Would it surprise you to know that the price you pay for fossil fuels could be as little as 20% of their real cost? That's because they're often subsidised by the government. Cynics would say that this is to keep prices low and ensure that business keeps booming for the people who control the resources and, in many ways, history shows they're right.
Compared to the calculations required to size a solar thermal hot water system, space heating is complicated. There are so many more variables to consider – building size, heat loss, insulation, air flow and everything else – so the best place to start is with the current heating load. From there, you can calculate how big your solar thermal installation needs to be, just like you would with a hot water system.
Many people who consider installing renewable energy systems in their homes are put off by the relatively high investment. Why would you choose a solar thermal system that could cost thousands of dollars when you can buy an electric water heater for a couple hundred?
