It's a no-brainer, but you'd be surprised how many people do not sit down and plan every aspect of their solar thermal installation before they go out and buy materials. Installing a solar thermal system is a huge project with far-reaching ramifications for your home: the equipment will be in place for decades, so you need to get it right or spend years messing around with expensive repairs and adjustments.
High-mass installations use a sand bed or pit underneath the building and a network of Pex tubes to gather, store and deliver heat to a radiant floor. They are extremely economical to run and provide very comfortable heating for the whole home. Remember to complete your installation in spring, so that the system starts gathering heat as soon as possible!
These systems have many advantages:
Pressurized solar hot water installations have a closed solar fluid loop that is always full of liquid. If the collectors get colder than the storage tank and are situated above the tank (as is usually the case), thermosiphoning can occur.
As the name suggests, a pressurized solar thermal system operates under pressure. In particular, the solar fluid circuit is always under a certain amount of pressure, which can vary enormously depending on the local climate and a variety of other factors. It is vital to understand the effects of pressure and how the system is managed to avoid catastrophic events.
Like any closed-loop installation, drainback solar hot water systems use a heat exchanger to pass energy from the solar fluid to the domestic water supply. However, drainback setups include a third, specialized tank – the drainback tank – which holds all the solar fluid when the system is idle. This fluid can still be very hot when circulation stops, so it makes sense to have a means of passing that energy to the domestic supply rather than waste it.
Integral collector storage (ICS) solar hot water systems are remarkably simple and cheap when compared to the other types. They don't use pumps, they don't need controllers, they use only one tank and they require very few extra components beyond a big water tank, some pipes and a pile of insulation materials.
Probably the least popular solar hot water installation, thermosiphon systems come in two types – direct and indirect – and are passive. They use no pumps but instead rely on the fact that hot fluids rise to provide circulation.
The simplest of the active solar hot water installation, flooded open-loop systems have water in the pipes, collector array and tank at all times. They are more complex than a passive system because they use a pump and controller, but compared to other active systems they are cheap and easy to install and maintain.
A recirculation solar hot water system is almost exactly the same as a flooded open-loop installation. However, it has one significant advantage: in times of very cold weather, it can recirculate warm water from the storage tank through the pipes and collector array to prevent freeze damage.
