What is a Solar Thermal Hot Water System?
A solar thermal system consists of a solar collector, hot water cylinder, adjoining pipe work, controller and essential safety equipment. Generally heat transfer fluid is pumped through the pipe work to flow from the cylinder through the collector and returns to the cylinder.
Mains water is passed through the cylinder where it is heated prior to being plumbed into the hot water system. The boiler may also be connected to a second heating coil (heat exchanger) in the cylinder and is used as the primary heating method during the winter and secondary in the summer. An immersion heater is also used to heat the water further and ensure it has reached the minimum required temperature.
The roof mounted equipment that receives the suns rays are called solar collectors and are currently available in three types;
- Direct flow evacuated tube
- Heat pipe evacuated tube
- Flat plate
The Riomay® DF120 & DF100 Direct Flow Evacuated Tube
The Riomay® advanced solar thermal system forms part of a simple, yet highly efficient energy transfer system that can heat water throughout the year. Whether your system is domestic, commercial, small or large, the principle is the same.
The Riomay® DF120 and DF100 is an advanced form of an evacuated tube solar collector which is designed to maximise the solar energy absorbed and minimise heat loss through radiation.
Developed and patented by Riomay® Renewable Energies, the revolutionary evacuated tube has substantially reduced the amount of ‘parasitic’ energy lost by most evacuated tube systems (Energy used up by the system itself during the process of converting solar energy to heat)
As a result the Riomay® evacuated tubes require smaller pumps to circulate the fluid in the evacuated tube collector which means that there are fewer drops in pressure through the system, giving a more sustained level of heat than almost any other system.
In fact, independent laboratory tests prove that the Riomay® DF120 produces over 750 kWh per square metre per year in direct heating mode and a staggering 850kWh per square metre per year in pre-heat mode. Click here for the downloadable technical details.
Simple but very effective - how it works
Inside each Riomay® tube is an absorber plate that gathers the sun’s energy and turns it into heat. The absorber plate is bonded to a copper pipe, and fluid passes through the pipe and collects the heat for transfer to a hot water system.
The whole assembly is sealed within a glass tube containing a high vacuum, and this virtually eliminates heat losses by convection or conduction. This type of water heating system is much more efficient and durable than a flat plate collector.
How does it produce hot water?
The heat transfer fluid passing through each panel is a solution of water and non-toxic antifreeze. This fluid absorbs heat from the Riomay® array and is pumped to a heat exchanger (coil) in the hot water tank. The heat then passes into the water, and the fluid is pumped back to the solar panel.
The pump is controlled by an electronic device that detects the temperature difference between the solar panel and the hot water tank. When the temperature in the panel is lower than the temperature in the tank, the system remains on standby. But when the sun raises the temperature in the panel to 4°C above the temperature in the tank, the temperature controller switches on the pump.
The system prevents energy losses at night and during the darkest days of winter, and the heat transfer fluid eliminates any risk of freezing.
For Architects
The Riomay’s DF120 and DF100 flexibility is outstanding: It can be installed flat on a roof, at an angle or horizontally on flank walls. The panels have been used as a attractive architectural features on homes, schools, leisure buildings and pergolas.
For Facility Managers
The Riomay® advanced solar thermal systems reduce the cost of heating water for changing rooms, laundries, kitchens, swimming pools, baths and showers. Converting to renewable energy is not just a matter of environmental responsibility – it is sound financial management.
For Developers
Government legislation means that installing renewable energy systems is a must. Be confident that you are giving your customers the best with a Riomay® advanced solar system.
The Riomay® High Performing System
The advanced system performance exceeds that of competing evacuated tube systems, thanks to:
- versatility - the system can go flat on roofs and walls, and the absorber plate is custom-angled in the factory to give you guaranteed maximum efficiency for the life of the system
- high transmittance glass, which is virtually transparent to solar energy
- a super-efficient selective coating on the absorber plate, which maximises the solar energy absorbed and minimises the heat energy lost by radiation
- a uniquely durable glass-to-metal seal at the end of each tube, to maintain the high vacuum that prevents energy losses by convection and conduction
- glass and metal components that expand and contract at the same rate in response to temperature changes, resulting in a reliable system built to last for more than 30 years
Feed In Tariff Information
The Government is currently reviewing the Feed in Tariffs for both commercial and domestic customers. It has proposed a reduction in the subsidies for projects of between 4kW and 50kW from 32.9p to 15.2p / kWh and to 21p for solar installations of up to 4kW in size, down from the current 43.3p/kWh. Confusingly, that whilst the original tariffs will no longer be available from 12th December, the new tariffs can only be confirmed after the government consultation period that finished on 23rd December 2011. Please see our website following this date for confirmation of the proposed rates.
