Environmental Engineering Reference
In-Depth Information
the collector circuit. The related costs largely depend on the price for electricity.
At an electricity price of 0.19 €/kWh and a demand for electricity between 0.008
and 0.03 kWh per provided kilowatt hour of thermal energy, operation costs are
around 6 to 10 €/a for decentralised solar thermal systems for domestic hot water
heating and between 18 and 25 €/a for solar combined systems. Maintenance costs
for most parts of the system are between 1 and 2 % of the overall investment
(without installation and commissioning) /4-14/. Thus, the entire annual mainte-
nance and operating costs for solar thermal domestic water heating and the com-
bined systems are at approximately 0.9 to 1.8 % of the overall investment (includ-
ing installation and commissioning). In relation to the reference system SFH-III,
these are annual costs between 60 and 80 € (see Table 4.7, SFH-III).
For a larger solar-supported district heating system, annual total costs of ap-
proximately 1 % of the overall investment costs can be assumed for maintenance
and miscellaneous costs (e.g. insurance) (excluding installation and commission-
ing of the system) /4-15/. Costs for the annual electricity consumed by the collec-
tor circulation pump, plus, if included in the calculation, the pro rata maintenance
costs for the solar-supported district heating network have to be added (see Ta-
ble 4.7, reference system DH-I).
The costs mentioned in Table 4.7 are average costs for the respective system
components at a given configuration of the reference systems. The installation is
performed by a company; it also includes the connection of collector, storage and
heating boiler. The sensors and the control instruments, the pump plus all devices
for security control (e.g. security and shut-off valves, expansion tank) are com-
bined as control costs.
Saving of tiles, plus investment costs for domestic hot water storage without
solar support, is credited to the solar system. Thus, only those additional costs are
allocated to the solar systems that result from the necessary increase in storage
volume compared to conventional domestic hot water storage.
Heat generation costs.
The specific energy supply costs can be derived from the
absolute investments indicated plus the costs for maintenance and operation. The
investments are amortised over the technical lifetime of the system (20 years,
Table 4.7). Under the financing assumptions (see Chapter 1) made so far, the re-
sults for solar thermal domestic hot water heating and combined systems in pri-
vate households (reference systems SFH-I, SFH-II and SFH-III, Table 4.7) are
costs between approximately 60 and around 85 €/GJ for the heat provided by solar
energy. The solar thermal system in the multi-family house is characterised by
specific heat generation costs of approximately 38 €/GJ (Table 4.7, reference sys-
tem MFH). For the solar district heating system, the costs for using short-term
storages are at approximately 32 €/GJ excluding a proportion of the solar-
supported district heating network and the house transfer station and at 46 €/GJ
including the latter (Table 4.7, reference plant DH-I). Doubling the heat genera-
tion costs by considering the network and the house transfer station is, on the one
hand, determined by the increase in investment costs by 40 % and the operating
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