Statistical Methods for the Storage Size Optimization in Solar Hot Water Systems

摘要

The optimal size of the short term store in a solar hot water system depends significantly on meteorological data. The crucial link connecting these data with the properties of the collectors, the heat demand and the store size, is the amount of backup energy per year which has to be secured from secondary sources. We propose that this connection can be formulated in the most concise way by the introduction of statistical concepts. In a first step we derive a simple analytical formula relating the backup energy per month to the storage size and to the mean values and variances of the daily net heat input characteristic for this month. The meteo data of 8 years have been used to derive those quantities and the daily energy demand for hot water has been assumed constant. In the second step the values of these backup energies summed over the whole year have been validated by comparison with those obtained from a day-to-day numerical simulation. An agreement within <=6% has been found in most cases. By introducing the autocorrelation functions describing the memory of the weather, we have further improved this agreement. (ERA citation 11:019534)