Answer to Question 1
Standard automobile batteries have thin plates and are designed for high starting currents. Deep cycle batteries have thick plates and are capable of deeper discharge cycles, so they should be specified for solar electric systems.
Answer to Question 2
Life-cycle costs include all expenses over the expected life of a system. By using life-cycle costs, the system can be compared with alternatives including conventional systems. The initial cost of solar energy systems is usually higher, but may have lower operating costs and have almost no energy cost.
The Cell Cycle
Life Cycle of Lobster
The cardiac cycle showing systole and diastole.
The fate of carbon in the citric acid cycle
The phosphorus cycle "دورة الفوسفور"
The carbon cycle