California Solar Initiative Thermal Program

CSI Thermal Resource Page

Here are some useful documents and information about the California Solar Initiative Thermal (CSI Thermal) program.

Appendix D
Maximum Gallon per Day (GPD) Guideline Table for Multi-Family/Commercial Projects⁸

Type of Building	Gallons Per Day (GPD)
Apartments/Condos: Number of Units
2 to 20 Units	42 GPD
21 to 50 Units	40 GPD
51 to 100 Units	38 GPD
101 to 200 Units	37 GPD
201 Plus Units	35 GPD
Student Housing	13 GPD per unit
Military Barracks	13 GPD per unit
Hotels/Motels	15 GPD per unit
Retirement/Nursing Homes	18 GPD per room
Office Building without showers	1.0 GPD per person
Restaurants
Meal Service Restaurants	2.4 GPD per full meal served
Quick Service Restaurants	0.7 GPD per meal served
Elementary Schools	0.6 gal/student/day of operation
Junior and senior high schools	1.8 gal/student/day of operation
Coin-Op Laundries	2 GPD per lb. of laundry washed

(8) Small multi-family/commercial systems are those that displace 30 kWth or less.
Larger systems and systems not indicated on the above table must be metered for 60 days.

Multi-Residential/Commercial Guidelines

Solar Hot Water fluid collector square footage cannot exceed 1.25 times the GPD (Gallons Per Day).
One-tank systems must have a minimum of 1.25 gallons of storage per square foot of collector.
Systems with two or more tanks must have a minimum of 1 gallon of storage per square foot of collector.

Single-family residential systems will apply for incentives via a one-step process. For this application process, the applicant will submit an ICF and supporting documentation after the system has been installed and received a final signed-off permit. The incentive rate for each project will be determined based on the then-current rate when the application is approved by the PA.

Depending on the size of the SWH system, a multi-family/commercial project will follow either a two- or three-step application process. For multi-family/commercial projects, applicants will submit a Reservation Request Form (RRF) prior to the installation of the system to receive a reservation based on the then-current incentive rate. A reservation of incentive dollars provides the purchaser assurance that the reserved funds will be available when the incentive claim is made. The Applicant will submit an ICF and supporting documentation after the system has been installed and received a final signed-off permit.

Application Process

Sector	Application Process
Single Family Residential	1-Step
Multi-family / Commercial (30 kWth or less)	2-Step
Multi-family / Commercial (over 30 kWth)	3-Step

Application Fee Schedule for Large Multi-Family/Commercial Systems

Fluid Collector Sq. Ft.	Application Fee
462 – 4,000 sq. ft.	$1,250
4,000 – 8,000 sq. ft.	$2,500
8,000 – 12,000 sq. ft.	$5,000
12,000 – 16,000 sq. ft.	$10,000
16,000 – No Limit sq. ft.	$20,000

Examples of Multi-Residential Commercial Systems

CPUC Recommended Maximum:

(number of units) * (GPD number from chart) / (square foot of collector) = (number of collectors)

5 units * 42 GPD = 210 divided by sq. ft. of collector (210/27.67) = 7.5 Collectors
One tank system = 27.67 * 6 * 1.25 = 208 Minimum Storage

16 units * 42 GPD = 672 GPD / 27.67 = 24 Collectors
Two tank system = 27.67 * 24 = 664 Minimum Storage

52 units * 38 = 1976 GPD / 27.67 = 71.4 Collectors
Minimum Storage = 2080 gallons

Free Hot Water Analysis:

(Number of gallons of hot water needed per CPUC Guidelines) * (8.34, the energy required to heat fluid 1 degree) * (Delta-T, the desired water temperature – the incoming water temperature) = (Daily Btu’s required) / (SRCC collector daily Btu rating) = # of collectors

5 units * 42 GPD = 210 * 8.34 * 65 = 113841/28,400 = 4 Collectors
Minimum Storage = 27.67 * 4 * 1.25 = 138.25 Gallons

16 units * 42 GPD = 672 * 8.34 * 65 = 364291.2/28,400 = 12 Collectors
Minimum Storage = 27.67 * 12 = 332 Gallons

52 units * 38 GPD = 1976 * 8.34 * 65 = 10224000/28,400 = 37.7 Collectors
Minimum Storage = 27.67 * 38 = 1051 Gallons

The CPUC table (Appendix D) above indicates the Maximum GPD number, however, Collector BTU ratings vary from collector to collector and at Free Hot Water we like to be specific and use the CPUC guidelines for gallons per day and the SRCC efficiency standards for Free Hot Water collectors so we can determine the correct solar hot water system for your specific application.

Free Hot Water offers complete installation documentation and support and can refer you to one of our partner installers.

Solar Hot Water Systems should be purchased based on climate zone and hot water usage. For a free evaluation of a Solar Hot Water System for your residential or commercial application, please contact us.