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Photo 1: The large panel is the collector. Also four PV panels are visible, which produce solar electricity.
In 1997 we bought a solar water heater. From then on we are able to heat a part of our own
warm water requirement with the sun.
A standard solar water heater consists out of a collector (about 3 m2), a water pump and a water reservoir of 80 to 150 litres. The sun heates water in the collecor. This water is pumped round a closed circuit. The heated water is stored in the reservoir. Before use, this water is heated up to 60 degrees (if neccessary) by a geyser or an another water heater (heated by oil or gas). So you have never a cold shower...
Type of solar water heater
Luigjes (nowadays ATAG) Econorm horizontaal.
The 'EcoNorm horizontaal' has a horizontal water reservoir in contrast to most
other solar water heaters. This reservoir can be placed easely under a pitched
roof, requiring as less as possible space.
Water reservoir, collector and (natural gas fired) water heater
Contence: 110 litres
Sizes: 130 x 51 cm (length x diameter)
Position water reservoir: horizontal on floor
Collector: 2,8 m2
geyers/another water heater: A high efficient central heating system; the ATAG blauwe engel II
Oriëntation
On the roof, back of our house was space for the collector.
Photo 1: The large panel is the collector. Also four PV panels are visible, which
produce
solar electricity.
The water reservoir is placed under the central heating system in a cupboard on the attic.
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Photo 2: The water reservoir (blue).
An average Dutch household requires about 400 m3 natural gas per year for
water heating. Taken into account the orientation of the collector, with this boiler
we save about 25% of this amount. 100 m3 natural gas is about 10% of
our total annual natural gas requirement.
With a gasprice of 40 to 50 eurocent per m3, we save 40 to 50 euros per year.
The best choice, a solar water heater, or solar electricity (PV), depends on several aspects. Below I describe some of these aspects.
A set of 4 PV solar panels (700 Wp) costs about 3500 euro (2008), including installation and mounting materials. In 2008 the Dutch government introduced a bonus of 33 ct/kWh produced by new systems, for 15 years of its lifetime.
A solar water heater costs about 2.500 euro. Together with a new central heating system, you will have to pay 4.000 to 5.000 euro. From september 2008 there are new Dutch subsidies for solar water heaters.
In the house the PV system requires a negligible amount of space for the inverters and an electricity outlet to make a connection to the grid.
A solar heating boiler requires much more space in the house. A relatively large reservoir for the heated water is required. Also two pipes between the reservoir and collector and a connection to the central heating is required. All parts of the systems have to be placed as close as possible to eachother.
PV solar panels can be mounted on the roof by yourselves. Also, for smaller systems (smaller than 600 Wp, about 5 m2) the electrical installation can be made by yourselves. If the system is larger, the electrical connection to the grid must be made (or examined) by a certified fitter.
A solar water heater can not be easely installed by yourselves. The collector is larger and a connection to the central heating system has te bo made. In most cases a fitter is required. Also the central heating system has to be suitable for a solar water heater.
If your roof is not too large, and you want to save maximal on your (primary) energy requirement, choose the maximal efficiency per m2 roof.
A 100 Watt peak optimal placed PV solar panel (about 0,85 m2) produces in the Netherlands on average 76 kWh per year. This is about 90 kWh per m2 per year. To produce 90 kWh, a power station needs 0.9 GigaJoule (GJ) primary energy. This is about 30 m3 natural gas. A solar water heater with a collector of 2,8 m2 produces About 3 GJ per year. Per square metre roof 1,1 GJ is produced, about 35 m3 natural gas. The solar water heater produces per square metre roof a bit more energy, but the difference is quite small.
The actual production of solar panels can be measured quite easy with a kWh meter.
The actual production of a solar water heater is quite difficult to measure. Besides the quantity of warm water, also the difference in temperature between the in and out going water has to be measured. Leon Bruinen from SolSolutions points at a meter which measures the amount of energy by taling into account the difference in temperature and the volume. This kinds of meters are also used for accounting the energy use for warm water in apaartment buildings. The meter costs about 2000 euros.
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