Making good on a resolution

Written by erin


We had a very exciting evening at my house yesterday. At about 6:30 pm, my husband interrupted my post-run shower to tell me that the our hot water heater’s inlet pipe — the one that fills the water heater from the City’s supply lines — was hot.

“You actually put your hand on it?” I said, a bit incredulously.

“No, no, on the insulation,” he assured me. “The insulation is just warm, I’m sure the pipe is very hot.”

This was good news. It meant that as my shower depleted the hot water tank, it was being replenished with water that was already hot.

Not to be outdone, I waited until his post-exercise shower was finished, then went out to the garage and listened closely. No whooshing natural gas noise.

“Hey,” I shouted. “The water heater isn’t heating!”

I repeated this ritual no fewer than 3 more times over the course of the evening. I did it when my daughter took her shower. And when the dishwasher was running through its first cycle. And when it was running through some other cycle, just to be sure.

Throughout the evening, the water heater performed perfectly, delivering nice hot water without ever tripping the temperature sensor (usually tripped by cold water coming in from the city to replenish the warm water we use from the tank). As a result, the natural gas flame never ignited and we enjoyed fossil-fuel-free hot water.

The joys of a solar water heating in action!

As I noted in an earlier blog post, I pledged to install a solar water heating system as my New Year’s resolution. My utility enacted an incentive program enabled by a recent state law, and mine was the first project installed under that program by my contractor.

I learned a few things about solar water heaters. The concept is extremely simple: divert the incoming city water to your roof, let it get hot up there, then send it down “pre-heated” to your existing water heater. Indeed my neighbor has a jury-rigged system that does exactly and only that; they’ve piped the city water up top where a long, rugged, black hose snakes back and forth several times before returning to a joint which send the water down to the water heater. This arrangement probably cost a few hundred dollars (including labor) many years ago, and I assume it has served them well.

That system has several pitfalls, however. The water in the big black hose can freeze. The hose can degrade and leak. Squirrels can chew on it. I suspect it wouldn’t pass a building inspection, and perhaps most importantly, it doesn’t make the best use of the sun’s energy.

Among modern engineered systems, there are two broad categories: passive systems and active ones. Passive installations are similar to my neighbor’s in that the city’s water pressure is the only source of energy required to move water through the system. Turn on a hot water faucet and the water moves. No electricity needed, no moving parts. Active systems, on the other hand, use a pump which circulates either the water or a heat-transfer fluid (like antifreeze) up into the sun and down into the water tank. Since it uses a pump, active systems can include electronic controllers which optimize the system’s efficiency and minimize the need for the fossil-fuel system to kick in. Heat-transfer fluid systems are great in areas where the temperature routinely drops below freezing.

Since I live in temperate northern California, I chose a passive system (pdf). It’s less expensive and I like the fact that there’s virtually nothing to maintain. My water moves through a series of copper tubes treated with a selective surface coating, all contained within a collector panel. The collector panel is designed to minimize heat loss and positioned to maximize sun exposure.

We’re thrilled with our system. We’ll benefit from a federal solar tax credit (available for systems installed before December 31) as well as our utility rebate. All-in, my cost will be about $3,800 and will pay back in about 7 years.

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  1. solar water heating

    We supply and fit the solar vacuum systems in the UK, slightly more expensive then the passive system that you have installed, but we think more efficient for the UK Climate. You say that you have a temperate climate in northern California I would be very interested to see how your system performs in the winter months.

  2. Marcia

    Great concept, but relatively few families in my community could afford to plunk $3,800 into a water heating system, myself included. Being that I live in NW Pennsylvania I would have to invest in the even more expensive active system. Are there any solar hot water systems out there that are easier on the pocketbook?

  3. Jay

    There are cheap devices, like the one on, and if you’re handy you could buy from a dealer, like the solarstore and do your own, but if you aren’t handy and you want something that will last and be reliable, you’re pretty much stuck with whatever a contractor will charge. I paid $11K (before the $2300 in incentives) to put together a closed-loop theromosiphon-type solar heater feeding into a gas-burning on-demand heater. My utility billed me for 1 therm of gas in July and zero in August. The gas only comes on when the water in the insulated pipe between the solar storage tank and the gas heater gets below 110 degrees, and it only stays on a few seconds (just long enough for hot water to be drawn into the pipe). My system has the advantage of not being subject to freezing. I see the whole thing as a cut in my carbon footprint, not a way to save money.

  4. Andre

    In Australia, perhaps obviously, solar water heating is relatively common – even in the cooler southern areas where winter temperatures are routinely below freezing.
    Living in a smaller terrace-style house in inner Sydney, I saw the benefits of having a roof mounted water tank & solar panel just like this: to save space as well as energy. 13 years later the system is still going strong. I don’t have an automatic booster, just a switch in the kitchen so even in winter I can wait until the sun’s given up before I use any energy to heat the water.
    There are several cometing brands/ manufacturers here, and yes they do charge a premium. But I’ve calcualted my payback to be within 5 years and I didn’t have the option of a gas booser, increasing my annual running costs slightly.

  5. SOLAR

    Yes! Keeping in mind the drastic environmental changes and rising fuel prices going Solar is one option open to all at minimal investments. The Solar Water heating systems are so easy to install and most of them come in a Do-it Yourself kit, With the technological advancement the once heavy, bulky hard to move panels are now available widely in light weight easy to carry by one personal only packages. The advancement in technology is not only limited to light weight, but for those concern about the aesthetics of the panels, the good news is that the panels are now available with a variety of trim colors to choose from and can be easily matched to your roof. Saving about $25.oo on ones electricity bill every month on a residence of 4. We all use hot water, as one of our basic needs and what can be a better way, than helping our environment, saving our resources and ourself’s some money other than by investing in a Solar Water Heating System.
    There are a couple useful websites I’m aware off, that I would like to share with you
    1. – is a comprehensive source of information on state, local
    , utility ans federal incentives that promote renewable engery ans energy efficieny.
    2. – one of the many manufacturers of certified Solar Water Heating Systems available. One place I saw the light weight panels and trim color options I was mentioning earlier.
    Lastly, the local utilites in some areas also provide additional rebates and incentives for adding a Solar Water Heating Sytem to your exisitng water tank.
    Keep the look out on. Feel Good and save- money for you, environment for us.

  6. Alex Kelley

    Fortunately, the federal tax incentives for solar water heating have been extended for 8 years. Here in Illinois, we can see a 50% cut in the installation price of a system when you combine the state and federal tax credit. We need to install active systems with anti-freeze in the Chicago climate to avoid freeze damage to the components.
    Our real estate market is beginning to recognize the value of solar. Anecdotal evidence is confirming the rule of thumb of $20 added to the home price for every $1 saved in energy bills. This fact is a great reason to install a solar water heater even if you don’t plan to live in the house for very long. You can more than pay back the installation costs once you sell it.