Solar (C-46) · Lesson 1 of 6

Single-Family PV Sizing: Equation 150.1-C

"Single-Family PV Sizing: Equation 150.1-C" is lesson 1 of 6 in the Solar (C-46) Learning Hub. It opens with "The Rule: Every New Single-Family Home Gets PV" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. The Rule: Every New Single-Family Home Gets PV
  2. Equation 150.1-C: Two Terms, Two Table Factors
  3. The Roof Cap: SARA Times 18 or 14
  4. Know the Five Exceptions
  5. Run the Check in Order

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Evaluate the SARA cap" through "Test the exceptions".

What you'll be able to do

  • Explain the main idea of "Single-Family PV Sizing: Equation 150.1-C" in plain language you can use on the exam.
  • Apply this step with confidence: "The Roof Cap: SARA Times 18 or 14".
  • Apply this step with confidence: "Know the Five Exceptions".
  • Apply this step with confidence: "Run the Check in Order".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Single-Family PV Size: Equation 150.1-CNew home: CZ 12, 1 dwelling unitCFA 2,400 sq ft | SARA 600 sq ft (steep)TABLE 150.1-C, CLIMATE ZONE 12A (CFA factor) = 0.613B (dwelling-unit factor) = 1.40THE CALCULATIONkW = (CFA x A)/1000 + (N x B)= (2,400 x 0.613)/1000 + (1 x 1.40)= 1.471 + 1.40= 2.871 kWdcRoof cap: SARA x 18 = 600 x 18= 10,800 W = 10.8 kW (larger, soEquation 150.1-C is the smaller)Exception 5 (JA12 BESS, 7.5 kWh min):2.871 x 0.75 = 2.15 kWdc allowedException 2: none if size is under 1.8 kWdcMinimum PV size = 2.87 kWdc (2.15 kWdc with qualifying BESS)Source: 2025 California Energy Code Sec. 150.1(c)14, Equation 150.1-C, Table 150.1-CCC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: The Rule: Every New Single-Family Home Gets PV

2025 California Energy Code Section 150.1(c)14 says all single-family residential buildings shall have a newly installed photovoltaic (PV) system (or newly installed PV modules) meeting the qualification requirements of Joint Appendix JA11. The annual electrical output must be no less than the smaller of two numbers: the size from Equation 150.1-C, or the building's solar access roof area (SARA) times 18 for steep-sloped roofs (times 14 for low-sloped roofs). This is the first number a solar contractor sizes a new-home system to.

Step 2: Equation 150.1-C: Two Terms, Two Table Factors

Section 150.1(c)14 prints the equation as kWpv = (CFA x A)/1000 + (Ndu x B), and the result is the kWdc size of the PV system. CFA is the conditioned floor area in square feet, Ndu is the number of dwelling units, and A and B come from Table 150.1-C by climate zone. For example, Table 150.1-C lists Climate Zone 12 as A = 0.613 and B = 1.40, and Climate Zone 3 as A = 0.628 and B = 1.12. Divide the CFA term by 1000 so it comes out in kW.

The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

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