Using Solar Panels for Optimum Efficiency

A Solar Panel System used in Ireland
generally comprise of all or most of
the following components.

Optimization of these is important to obtain best benefits desired.

  • Solar Collector – As the name implies its function is
    to absorb the beams of energy that impinge on it for
    beneficial use later. The most popular place for the
    collector is the roof top of a building. The best
    orientation of the panel for optimum year round solar
    thermal energy absorption is facing south.When it comes to the tilt the best positioning will be  30 0 – 45 0,
    but when this is not possible, any tilt angle between 15 0 to 50 0
    (to the horizontal) would be satisfactory. The commonly used types
    of collectors are (a) Flat Plate design and (b) Evacuated tube design.The later is better for energy efficiency but more expensive.
    If you are interested in getting a rebate for your installation
    evacuated tube type provides the higher grant.
  • The Cylinder – The collector cylinder sizing is important as too small a tank would over heat the water.
    Too large a tank would take a longer time to heat up water and may also not be heated to the required temperature.
    (It will be bad  economy as well). The minimum permitted storage temperature of hot water is 60 0 presently to prevent Legionella growth. The heat of water off the cylinder therefore should be a few
    degrees at least higher (to allow for heat loss in transit).

The recommended aperture sizes for the cylinders are:

Maximum cylinder temperature 60 0 C     – Aperture equivalent area = 70 m2

Maximum cylinder temperature 80 0-90 C – Aperture equivalent area = 50 m2


In climates similar to that in Ireland the type of cylinders called Dual Coil design should be preferred.
The bottom coil is connected to the Collector while the top level coil is connected to a auxiliary circuit meant for a supplementary hot water source.

  • The Heat Storage – This is really an insulated tank which stores the thermal energy rich water flowing out of the Collector. This method of storing solar energy is so simple and basic creating little or no problems for the end user during its life time. Being an insulated tank the preferred location is indoors.
  • Pump– The circulation pump may be standard domestic power supply operated or from a Solar PV panel array generated power operated. In Ireland the preferred is the former. The pump is responsible for transferring the Thermal Energy of the sun collected by the collector to the storage unit.
  • Safety and Regulatory devices – The Hot water system deals in very hot water (which sometimes reaches boiling point) and also hydraulic circuits pressurized to at least some low pressure. The appropriate safety devices such as suitable piping material, thermostats, gauges, relief valves, shut-off, regulatory and mixing valves etc should be incorporated in the system.
  • Auxiliary Heat Source – In Ireland in winter the solar thermal power is not that reliable for your total requirement, though it is available throughout the year. At best only about 60% of the total heat requirement would be met during this period or in bad weather. An auxiliary source of thermal energy such as a Pellet Stove/boiler, gas, oil or wood fueled heat source, electric heaters, etc  therefore need to be incorporated in a system as a back-up.


Thanks the Techstore Team

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