## Example

Find the payback time for the previous example and check the rate of return graphically.

GIVEN

first year savings (-DQ) pe = \$7481 N = 20 yr extra investment DCcap = \$30,000

rate of return r or r

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payback time Np [yr]

### FIGURE 8.5

Relationship between rate of return rr, system life N, and payback time Np. If re = escalation rate of annual savings, the vertical axis is the variable rr,e from which rr is obtained as rr = rre (1 + re) + re.

30 25

payback time Np [yr]

### FIGURE 8.5

Relationship between rate of return rr, system life N, and payback time Np. If re = escalation rate of annual savings, the vertical axis is the variable rr,e from which rr is obtained as rr = rre (1 + re) + re.

## Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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