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California Solar: Why Every Apartment in California MUST Install Solar Thermal Water Heaters

Today we have a guest blog post from Solar Fred at about the financial benefits of solar thermal water heaters for apartment owners.


Owners of California apartment buildings are one of the businesses that will benefit most from going with a solar hot water system.

Traditionally in California (and many states), apartment building landlords include hot water with every rental lease. Rather than individual hot water heaters, a central water heater (typically powered by gas) provides hot water to all residential units and onsite laundry facilities.

Consequently, with every bath, shower, dish washing, or load of laundry, the landlord is spending money to heat the hot water for the building’s residents. Installing a solar hot water system is a way to save 80% of that solar hot water cost.

Let’s take an example of an apartment or condo complex with about 120 units and 160 residents. While this is a real life example, please remember that every apartment building is unique with different requirements and water usage. For each unit the calculation is as follows: 20 gallons per person per-day for the first person, 15 gallons per-day for the second, and 10 gallons per-day for each person thereafter.  Also included in the calculation are the 12 front-load energy saving washers to a total hot water consumption of 3,000 gal/day

So, even if you own another 160 resident building in California, your costs may be more or less than the following example.

Solar Hot Water Cost and Savings Example for a California Apartment Building with 160 Residents



Min.Daily Demand @ 80% BTU


Est. Water Storage Requirements

3,000 Gallons

# of Free Hot Water 7000 collectors:

66 panels

Roof area required:

3,500 sq. ft

Est. gas bill for hot water before solar:


Est. Cost before rebate, incl. engineering


Estimated California Rebate:

$ -86,000

Estimated 30% Federal Tax Credit:

$ -54,000*

Estimated Net System Cost:


Estimated Payback time:

About 3 yrs!

CO2 Saved from the environment over 25 years:

3 Metric Tons

* Marcs 5 yr accelerated depreciation may be available and is not included in the ROI calculations.  Please consult with your tax attorney as for your eligibility.


Once again, it should be noted that every apartment building is different. The number of units, number of residents, type of washers, type of dish washers, hot water tanks, engineering, roof space and many other factors will affect individual costs.

Also, these figures are rounded and based on the expected PG&E rebate. However, as of August 2010, the rebate regulations are still being finalized by The California Public Utility Commissions (CPUC) may alter these numbers.

According to sources, the CPUC should finalize the regulations by some time in September. Consequently, now is the time to get your solar quote and start the design and engineering to get reserved on the first tier of California rebates. Rebate amounts will decrease as the number of installations rise, so early adopters will get the most generous part of the subsidies.

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