Solar energy – a dream comes true

Marstal District Heating

It has been a dream for many to use solar energy for heating and hot tap water. So far, the only problem has been that it is expensive to install devices to catch solar energy. At individual buildings it is normally very expensive and therefore not yet a sustainable solution.

Fortunately, the solar heating industries and district heating companies in Denmark have developed concepts for large scale solar heating plants, which can produce hot water in a cost effective way. The larger the cheaper. Plants larger than 10.000 m2 can produce hot water up to 90 dgr. C at a price of 200 DKK/MWh.  It is competitive with oil boilers without taxes and subsidies.  From an energy efficiency point of view it is also interesting at it is the most efficient existing technology to catch the solar energy – even 100 times more efficient than the green plants.

In Denmark such a large scale plant can produce 500 kWh/m2/a or  5.000 MWh/a –   in warmer climates it could be up to 10.000 MWh/a.

In combination with an ordinary thermal storage tank, the solar heating plant can provide the consumers with a uniform load of heat during the summer period and even contribute a bit in the winter period.

A precondition is that there is a heat demand to use all the available solar heating from such a large plant.

That could be an industry, which use process heat at temperatures below 90 dgr. C or it could be a district heating system.

In Denmark we have a district heating system in almost all urban areas. Therefore, this market is booming at the moment and we foresee that there will be installed up to 4 mio. m2 of panels in Denmark within the next 10 years. In combination with seasonal pit stoages, we may, according to prognosis from Heat Plan Denmark 2010, even expect up to 8 mio. m2 before 2030. Solar heating distributed via district heating from one end of the town to the other is probably one of the most obvious examples on the benefits of urbanisation.

In Asia and America we can see that there is a great interest from private  industries, which on purely commercial conditions wants to save money and be greener.

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2 Replies to “Solar energy – a dream comes true”

    1. Thank you for the comment.
      I fully agree that mass production is one of the factors, which will reduce the costs of solar heating and solar power PV as well as most other energy technologies.

      Another important factor is the large-scale factor. Namely, that the cost per unit is recuced dramatically if you increase the scale.
      As for the solar thermal plants, which I have focused on in my blog, both factors have had a positive influence already:
      1) The cost in DKK/MWh of the thermal energy from large-scale plants (more than 10.000 m2 of panels at a field) are only around 15 % of the costs from small plants (4 m2) at buildings.
      2) The large panels for the many large-scale plants have stimulated a more efficient mass production at the leading Danish manufactures of these panels, which has reduced the costs per m2 panels, e.g. by installing automatic welding machines etc. The point is that we have to minimize the cost in DKK/MWh which is not the same as to increase the output in MWh/m2/a.

      You refer to solar power from PV and I suppose your comment actually is mainly adressed to theese solar PV plants.
      As for these plants we already have mass production of the expensive solar cells at large factories in the world, e.g. due to huge volumes of panels being installed in e.g. Germany and Spain due to subsidy progammes.

      This mass production of solar cells has reduced the costs in recent years, however not enough to make them competitive with large wind turbines even with large subsidies.
      The problem for solar PV is also that small plants on one family houses are relatively more expensive than large plants due to the costs of installation, and this installation cost can hardly be reduced more as it depends on costs of local labor and standard components. Therefore it will not help if many individuel houses install solar PV panels. Installation of such small expensive plants can not be justified by the hope that prices will be reduced in future. There is simply no connection between such huge investments and the hope.

      According to the information I have, it is absolutely not cost effective to install small solar PV plants at individual buildings, which are connected to the power grid. We should use the money for off shore wind farms instead and use the power grid to transfer the power to the buildings. Such an intelligent use of the power grid has been one of the most important measures to make the Island Samsoe in Denmark to be the first “CO2 neutral island” in the world (on annual basis).

      It is also much better to install them at buildings and devices which do not have access to the power grid. One example is the many houses in the remote areas in the mountains in Norway. Another example is the parking automats in Copenhagen.

      In fact solar PV combined with car batteries and a 12 V installation can provide any home without access to the grid with most electrical energy services for TV, radio, LED lights, computers, vacuum cleaners etc. in a cost effective way. Many homes in the remote areas of the world have still not access to the power grid and may not need it due to this development. So let us use the money on improving quality of life for these families in a cost effective way and not wasting them on inefficient expensive projects.

      If you want to know more about large scale solar thermal, you may study the solarge project: http://www.solarge.org/index.php?id=805

      Or you may have a look at our solution at Energy map and the attached media: http://www.energymap.dk/Profiles/Ramboll/Solutions/Large-scale-solar-water-heating

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