How Efficient is a Solar Collector?
As you should already know, choosing the most efficient collector for your solar thermal installation is more about your situation, location and climate than it is about just picking the top-rated one off a list.
Thermal
You are here
How Durable is a Solar Collector?
As you are probably aware, the SRCC (www.solar-rating.org) rates both efficiency and durability from the results of ASHRAE's (www.ashrae.org) tests. Thankfully, durability is less of an issue when you're comparing solar collectors because the vast majority of manufacturers build their products to last.
Climate Considerations for Solar Collectors
When it comes to your local climate, there are some factors that can seriously affect your choice of collector type. The worst non-catastrophic climatic event for solar thermal installations is, without any doubt, snow. It's the worst because, unlike rain or total cloud cover, it can physically pile up on top of the collector and block out the sun's light.
Solar Fluids in Solar Thermal Systems
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.
Using Propylene Glycol in Solar Thermal Systems
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.
Solar Thermal Expansion Tanks
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.
Sizing Pumps in Solar Thermal Systems
One of the most complicated components to size in any solar thermal installation is the pump (or pumps if your chosen schematic requires more than one). All solar thermal pumps are centrifugal models, using vanes or paddles which spin within an enclosed space to create pressure. Your choice of pump will depend on the type of system and two measurements: flow and head.
How to Size a Solar Thermal Space Heating System
A solar thermal space heating installation with storage is one of the most complicated systems to size. There are so many variables: storage size, collector array size, expansion tank size, piping size, heat exchanger size and heat load requirements. There are two ways of working out how big everything needs to be: the complex mathematical way or by rules of thumb.
How to Size a Solar Thermal Space Heating Collector Array
Space heating with solar thermal installations revolves around Btus. If you've sized the heat generation part of your system already, you'll be familiar with this. The next step is to work out how big the collector array needs to be.
Flat Plate Collector Structure
The oldest, simplest and most common solar thermal collectors are flat plate collectors. They have a robust design that can withstand temperatures falling well below zero and rising well above most climate norms (they work fine at around 180°F or 82°C). It's no surprise that they're the base to which all other, more complex collectors are compared.
Pages
