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Solar panels on roof

2 years ago

To help heat water

Comments (10)

  • 2 years ago

    Yea, I think people here are going to need a tad more.

  • PRO
    2 years ago

    uh yeah.

    assuming the water heater is electric. if it's not, solar would be to make you feel good?

    How much you pay for electric in KWH? how many cents per KWH. Less than 15 cents, it would likley be a losing proposition.

    How big is your family, how much do you use hot water? without use, solar is not likely to ever pay for itself.

    Room? real estate? do you have the room for solar, exposure to southern sky that would make solar most effective.

    If you determine solar is worth it, the pay off might be 20 some odd years from now. There's better investments that pay far greater, far faster returns than that.

    Just recently the Tesla solar roofing panels haven't panned out as Elon Musk has said... sounds like another solyndra solar failure in the making.

    China is supposedly leading the charge in producing solar panels. However, China has also been in the news as having wide spread black outs? That should make you question a few things, shouldn't it?

  • 2 years ago

    Your understanding seems limited and partially wrong.

    The first and I think still most prevalent type of solar panels use silicon wafers. The same material, made the same way, as the basic building block for semiconductor (solid state) devices. When the solar industry was just gearing up, it caused a silicon wafer shortage (and resulting device shortage) for the world of electronics until new manufacturers could gear up. As one of my semiconductor client CEOs said at the time, something to the effect of "When a semiconductor fab orders silicon wafers, other than for the few big boys, it's some hundreds of wafers per order. When a solar cell manufacturer orders wafers, it's for dozens and dozens of tons." Wafers are a commodity business - high volume, low margins, sensitive to labor costs. More than 15 years ago, the wafer market geared up in China and there it remains. Plants in other places, including the US, closed. For both solar cell buyers and for semiconductor ones, most wafers come from China. Nothing has changed recently.

    So long as there's sunshine, solar cells are reliable and long lasting. No moving parts. My thought for electric water heating where electricity costs are high would be to use solar cells, if natural gas isn't available. Also, to get a heat pump water heater, much more economical to operate than straight resistance heating ones. .

    Not unlike its cars, Tesla has a tendency to prematurely overhype and over-promise product performance. It catches up with itself eventually. I'm not sure I would buy a Tesla solar system today but there are plenty of other sources that are excellent and do work well.

  • 2 years ago

    Interesting, mike. That water system must have had Rube Goldberg as one of its designers. How to take something simple and make it complicated.

  • 2 years ago

    That solar hot water system looks a bit complicated, but thermal solar (not PV, i.e. semiconductor) water heating has been around for many decades, at least in milder, sunny climates. Like even 30-40 years ago, when PV solar panels were still very expensive and had a 10+ year payback period, thermal solar was relatively inexpensive - in Hawaii where I grew up, electricity is expensive, and so thermal solar water heating could have a payback of <2-5 years. This was in comparison to straight up conventional electric resistance water heaters (no natural gas in Hawaii, and not trying to compare to electric heat pump water heaters that are an option now). Those systems had "panels" that look more like sheets of fabric sitting on the roof, than glass-encased panels. Similar to what you still see for solar pool water heating. Lots of them around my old neighborhood, and probably outnumber PV solar even today.

    Very simple in design and materials too. The drawback to them, I heard (but have no firsthand experience), was the tubing and seals tended to degrade and spring leaks after a few years, so could be challenging to keep reliably working well unless maintained. Perhaps also because the sunny, high-UV environments on the roofs. So probably a lot of those older systems still on the rooftops no longer working - but I'm sure all of them paid back their original cost and then some. Not sure if newer designs have improved materials and reliability.

  • 2 years ago
    last modified: 2 years ago

    The two of them contributed good info in this thread.

    Why do you think it is necessary for you to help us decide who is spamming?

    Are you an assistant moderator? lol

  • 2 years ago
    last modified: 2 years ago

    ALL of our hot water in Tanzania came from rooftop hydronic systems and I think they are quite common throughout Asia, Africa and Oz. They work well and are quite efficient in both energy and cost.

    In TZA they'll usually have the tank above the roof, this so that the water can be pre-heated in the tank and so that smaller and more efficient pumps can be used to get water to them (though in some communities you'll see larger tanks on hillsides with pipes coming down and distributed to rooftop solar systems.

  • 2 years ago

    OP never posted back. Given the brevity of his post, I suspect it was a late evening, alcohol-induced, spur of the moment, inspiration. He probably even forgot he posted!

  • 2 years ago

    Can you explain why solar panels are an unsustainable technology and create negative effects on the environment?