Typically a household solar heating system will consist of a solar collector/panel with a fluid flowing through it to transfer the heat energy collected to a hot water tank (often known as a thermal store or to household radiators. The solar panel is located somewhere south facing to achieve good light levels throughout the day, often on the roof of the building. A pump is used to move the liquid around the system and heat is taken from the panel and transferred to the thermal store.

Simple DIY water heating systems are relatively cheap and can be purchased in many places. The system consists of a heat collecting panel and an insulated water storage tank. During the day, the sun shines on the solar panel heating the water. The hot water rises into the tank and the cooler water at the bottom of the tank returns to the heat panel. This rotation of water causes all the water to heat up. This water is stored in the hot water tank for use later.

Solar water heaters generally split in to two types; these can be made of a simple glass topped insulated box with a flat solar absorber made of sheet metal attached to copper pipes and coloured black, or a set of metal tubes surrounded by an evacuated (near vacuum) glass cylinder.

If a solar system is being used to heat more than just domestic hot water, the system needs to be more sophisticated.

Being reliant on the sun does pose its’ own problems. If there is no sun, then there is no hot water from this source however even on a cloudy day, solar systems will create some “gain” in heat to the overall system.

Another addition to a solar heating system could include a solid fuel heat source such as a wood-fired stove or oven with a back-boiler. In the winter, the wood fired stove would be your main method for heating water. In the winter when the solar input is low you will still find that the solar can top up the thermal store with extra degrees of heat even on the coldest days if you have a little bright sky or sunshine.

One other point to consider is this. One of the most common methods of heating water in Portugal is using a wall mounted heater fired by a butane or propane cylinder. Obviously using a wall heater is not the most economic or environmentally friendly method, however it does give the user complete freedom. By adding in the extra element you do get the following advantage. Hot water from your thermal store can be topped up by the gas heater before it arrives at your taps so preventing the need to run off lots of water waiting for the water to warm. When the water coming from your thermal store is warm enough, the thermostat in the heater will cause the heater to switch off. The heater will also not ignite if the water from the tank is hot enough or if you run the water from the tap slowly.

The Portuguese Government is very keen to encourage the use of solar power in domestic use and it’s Ministry of Economy and Innovation does release grants on a regular basis. Typically you will get a discount on the purchase price, an IRS deduction on your tax and may be able to get a loan for the balance of the cost. Find out if your local installer is involved in the scheme as he will know how to apply for these grants.