Solar
Environmental Engineering · FE Reference Handbook section
Handbook notes for this section
Definitions and conditions exactly as the handbook states them.
- TYPICAL SUMMER DAY TYPICAL WINTER DAY
- 50 SOLAR MODE 50 SOLAR MODE
- Note: Correlation of solar generation to peaking power requirements
- Spacing of Solar Flat-Plate Collectors to Avoid Shadowing
Core formulas for this FE topic
Definitions, applicability, units, assumptions and worked examples for each relation.
This section is conceptual; there are no equations to memorise.
Worked exam-style examples
The four ways this section is written on the real exam — thoughts first, then equations, then substitution.
solar power output from a photovoltaic array installation Given panel conversion efficiency (eta) = 0.1250; panel array area (A) = 1,813 m^2; solar irradiance (G) = 370.0 W/m^2, determine the solar power output (P) in W.
Given
Find
solar power output (P), in W
Start with the thinking
- The governing relation printed in this handbook section is Solar.
- Everything except P is given, so isolate P symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Solar power output from a photovoltaic array depends on panel efficiency, array area, and incident solar irradiance.
Figure 1 — schematic for Solar — solve for solar power output — Solar
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for P:
Step 3 — List the givens: panel conversion efficiency (eta) = 0.1250, panel array area (A) = 1,813 m^2, solar irradiance (G) = 370.0 W/m^2.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning P = 83,851 W to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 167,703 — kept a factor of two that cancels in the correct rearrangement.
- 41,926 — dropped that same factor in the other direction.
- 92,236 — rounded an intermediate value before the final step.
Reference: FE Handbook — Solar Energy
solar energy conversion calculation for a rooftop solar array Given panel conversion efficiency (eta) = 0.1740; solar irradiance (G) = 430.0 W/m^2; solar power output (P) = 3,166,540 W, determine the panel array area (A) in m^2.
Given
Find
panel array area (A), in m^2
Start with the thinking
- The governing relation printed in this handbook section is Solar.
- Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Solar power output from a photovoltaic array depends on panel efficiency, array area, and incident solar irradiance.
Figure 2 — schematic for Solar — solve for panel array area — Solar (2)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for A:
Step 3 — List the givens: panel conversion efficiency (eta) = 0.1740, solar irradiance (G) = 430.0 W/m^2, solar power output (P) = 3,166,540 W.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
A = 42322\ \text{m^2}Step 6 — Check: returning A = 42,322 m^2 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 84,644 — kept a factor of two that cancels in the correct rearrangement.
- 21,161 — dropped that same factor in the other direction.
- 46,554 — rounded an intermediate value before the final step.
Reference: FE Handbook — Solar Energy
solar power generation as a function of irradiance and panel area Given panel conversion efficiency (eta) = 0.1650; panel array area (A) = 7,345 m^2; solar power output (P) = 1,437,200 W, determine the solar irradiance (G) in W/m^2.
Given
Find
solar irradiance (G), in W/m^2
Start with the thinking
- The governing relation printed in this handbook section is Solar.
- Everything except G is given, so isolate G symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Solar power output from a photovoltaic array depends on panel efficiency, array area, and incident solar irradiance.
Figure 3 — schematic for Solar — solve for solar irradiance — Solar (3)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for G:
Step 3 — List the givens: panel conversion efficiency (eta) = 0.1650, panel array area (A) = 7,345 m^2, solar power output (P) = 1,437,200 W.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
G = 1186\ \text{W/m^2}Step 6 — Check: returning G = 1,186 W/m^2 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 2,372 — kept a factor of two that cancels in the correct rearrangement.
- 592.9 — dropped that same factor in the other direction.
- 1,304 — rounded an intermediate value before the final step.
Reference: FE Handbook — Solar Energy
solar power output from a photovoltaic array installation Given panel conversion efficiency (eta) = 0.2010; panel array area (A) = 6,245 m^2; solar irradiance (G) = 435.0 W/m^2, determine the solar power output (P) in W.
Given
Find
solar power output (P), in W
Start with the thinking
- The governing relation printed in this handbook section is Solar.
- Everything except P is given, so isolate P symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Solar power output from a photovoltaic array depends on panel efficiency, array area, and incident solar irradiance.
Figure 4 — schematic for Solar — solve for solar power output (case 2) — Solar (4)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for P:
Step 3 — List the givens: panel conversion efficiency (eta) = 0.2010, panel array area (A) = 6,245 m^2, solar irradiance (G) = 435.0 W/m^2.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning P = 546,032 W to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 1,092,063 — kept a factor of two that cancels in the correct rearrangement.
- 273,016 — dropped that same factor in the other direction.
- 600,635 — rounded an intermediate value before the final step.
Reference: FE Handbook — Solar Energy
solar energy conversion calculation for a rooftop solar array Given panel conversion efficiency (eta) = 0.2000; solar irradiance (G) = 475.0 W/m^2; solar power output (P) = 3,408,790 W, determine the panel array area (A) in m^2.
Given
Find
panel array area (A), in m^2
Start with the thinking
- The governing relation printed in this handbook section is Solar.
- Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Solar power output from a photovoltaic array depends on panel efficiency, array area, and incident solar irradiance.
Figure 5 — schematic for Solar — solve for panel array area (case 2) — Solar (5)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for A:
Step 3 — List the givens: panel conversion efficiency (eta) = 0.2000, solar irradiance (G) = 475.0 W/m^2, solar power output (P) = 3,408,790 W.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
A = 35882\ \text{m^2}Step 6 — Check: returning A = 35,882 m^2 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 71,764 — kept a factor of two that cancels in the correct rearrangement.
- 17,941 — dropped that same factor in the other direction.
- 39,470 — rounded an intermediate value before the final step.
Reference: FE Handbook — Solar Energy
solar power generation as a function of irradiance and panel area Given panel conversion efficiency (eta) = 0.1950; panel array area (A) = 17,028 m^2; solar power output (P) = 595,640 W, determine the solar irradiance (G) in W/m^2.
Given
Find
solar irradiance (G), in W/m^2
Start with the thinking
- The governing relation printed in this handbook section is Solar.
- Everything except G is given, so isolate G symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Solar power output from a photovoltaic array depends on panel efficiency, array area, and incident solar irradiance.
Figure 6 — schematic for Solar — solve for solar irradiance (case 2) — Solar (6)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for G:
Step 3 — List the givens: panel conversion efficiency (eta) = 0.1950, panel array area (A) = 17,028 m^2, solar power output (P) = 595,640 W.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
G = 179.4\ \text{W/m^2}Step 6 — Check: returning G = 179.4 W/m^2 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 358.8 — kept a factor of two that cancels in the correct rearrangement.
- 89.6924 — dropped that same factor in the other direction.
- 197.3 — rounded an intermediate value before the final step.
Reference: FE Handbook — Solar Energy
solar power output from a photovoltaic array installation Given panel conversion efficiency (eta) = 0.1800; panel array area (A) = 15,967 m^2; solar irradiance (G) = 795.0 W/m^2, determine the solar power output (P) in W.
Given
Find
solar power output (P), in W
Start with the thinking
- The governing relation printed in this handbook section is Solar.
- Everything except P is given, so isolate P symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Solar power output from a photovoltaic array depends on panel efficiency, array area, and incident solar irradiance.
Figure 7 — schematic for Solar — solve for solar power output (case 3) — Solar (7)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for P:
Step 3 — List the givens: panel conversion efficiency (eta) = 0.1800, panel array area (A) = 15,967 m^2, solar irradiance (G) = 795.0 W/m^2.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning P = 2,284,878 W to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 4,569,755 — kept a factor of two that cancels in the correct rearrangement.
- 1,142,439 — dropped that same factor in the other direction.
- 2,513,365 — rounded an intermediate value before the final step.
Reference: FE Handbook — Solar Energy
solar energy conversion calculation for a rooftop solar array Given panel conversion efficiency (eta) = 0.2190; solar irradiance (G) = 500.0 W/m^2; solar power output (P) = 30,540 W, determine the panel array area (A) in m^2.
Given
Find
panel array area (A), in m^2
Start with the thinking
- The governing relation printed in this handbook section is Solar.
- Everything except A is given, so isolate A symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Solar power output from a photovoltaic array depends on panel efficiency, array area, and incident solar irradiance.
Figure 8 — schematic for Solar — solve for panel array area (case 3) — Solar (8)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for A:
Step 3 — List the givens: panel conversion efficiency (eta) = 0.2190, solar irradiance (G) = 500.0 W/m^2, solar power output (P) = 30,540 W.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
A = 278.9\ \text{m^2}Step 6 — Check: returning A = 278.9 m^2 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 557.8 — kept a factor of two that cancels in the correct rearrangement.
- 139.5 — dropped that same factor in the other direction.
- 306.8 — rounded an intermediate value before the final step.
Reference: FE Handbook — Solar Energy
solar power generation as a function of irradiance and panel area Given panel conversion efficiency (eta) = 0.1600; panel array area (A) = 399.0 m^2; solar power output (P) = 265,490 W, determine the solar irradiance (G) in W/m^2.
Given
Find
solar irradiance (G), in W/m^2
Start with the thinking
- The governing relation printed in this handbook section is Solar.
- Everything except G is given, so isolate G symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Solar power output from a photovoltaic array depends on panel efficiency, array area, and incident solar irradiance.
Figure 9 — schematic for Solar — solve for solar irradiance (case 3) — Solar (9)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for G:
Step 3 — List the givens: panel conversion efficiency (eta) = 0.1600, panel array area (A) = 399.0 m^2, solar power output (P) = 265,490 W.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
G = 4159\ \text{W/m^2}Step 6 — Check: returning G = 4,159 W/m^2 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 8,317 — kept a factor of two that cancels in the correct rearrangement.
- 2,079 — dropped that same factor in the other direction.
- 4,575 — rounded an intermediate value before the final step.
Reference: FE Handbook — Solar Energy
solar power output from a photovoltaic array installation Given panel conversion efficiency (eta) = 0.1250; panel array area (A) = 18,879 m^2; solar irradiance (G) = 635.0 W/m^2, determine the solar power output (P) in W.
Given
Find
solar power output (P), in W
Start with the thinking
- The governing relation printed in this handbook section is Solar.
- Everything except P is given, so isolate P symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Solar power output from a photovoltaic array depends on panel efficiency, array area, and incident solar irradiance.
Figure 10 — schematic for Solar — solve for solar power output (case 4) — Solar (10)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for P:
Step 3 — List the givens: panel conversion efficiency (eta) = 0.1250, panel array area (A) = 18,879 m^2, solar irradiance (G) = 635.0 W/m^2.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning P = 1,498,521 W to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 2,997,041 — kept a factor of two that cancels in the correct rearrangement.
- 749,260 — dropped that same factor in the other direction.
- 1,648,373 — rounded an intermediate value before the final step.
Reference: FE Handbook — Solar Energy