Storage capacity correction

It can be proven that the annual performance of liquid-based solar energy systems is insensitive to the storage capacity, as long as this is more than 50 L of water per square meter of collector area. For the f-chart of Figure 11.2, a standard storage capacity 75 L of stored water per square meter of collector area was considered. Other storage capacities can be used by modifying the factor X by a storage size correction factor Xc/X, given by (Beckman et al., 1977)

where

Mwa = actual storage capacity per square meter of collector area (L/m2). Mw,s = standard storage capacity per square meter of collector area (= 75 L/m2).

FIGURE 11.3 Storage correction factor for liquid-based systems.

FIGURE 11.3 Storage correction factor for liquid-based systems.

Equation (11.14) is applied in the range of 0.5 < (MwJMws) < 4.0 or 37.5 < Mwa < 300 L/m2. The storage correction factor can also be determined from Figure 11.3 directly, obtained by plotting Eq. (11.14) for this range.

Example 11.3

Estimate the solar fraction for the month of March of Example 11.2 if the storage tank capacity is 130 L/m2.

Solution

First the storage correction factor needs to be estimated. By using Eq. (11.14),

0.87

For March, the corrected value of X is then Xc = 0.87 X 2.08 = 1.81. The value of Y remains as estimated before, i.e., Y = 0.68. From the /-chart, f = 0.481 compared to 0.466 before the correction, an increase of about 2%.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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