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Comment by m463 | Hacker News Reader

Years ago, I was convinced that solar hot water heaters were ridiculously efficient and paid for themselves in just a few years.

Since that time, I've come to think that solar PV + an electric water heater is probably a better answer - easier to install, very little relative maintenance.

Now I wonder how solar PV + a heat pump water heater compares (especially if it doubles as a cooler for a surrounding room).

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That's what I did. My water heater is in the basement, and it keeps it dry during humid summers. (I live where we have humid summers.)

In my case, it makes sense because my solar PV is also to run heat pumps for heating and charging cars, and I have a good deal for net metering. Why have a separate hot water system running to my roof when I could just make the pv system a little bigger?

At least where I live, basements get damp in the summer and people have to run dehumidifiers. The heat pump water heater acts as a free dehumidifier that never needs to be drained.

Can you clarify the "never needs to be drained" part?

Most plug-in dehumidifiers (the kind you'd use in a seasonally-humid basement, most likely) are used where there there is no floor-drain, so the condensation is collected in a gallon-or-two-sized bucket that you have to empty periodically.

The plumber hooked it up to the same kind of condensation pump/drain that central AC uses.

In certain parts of the world (tons of Australia, parts of Africa) literally every single building has a solar hot water heater.

They are fantastic in hot climates, and should be littering the roofs in CA, AZ, TX, etc.

Not everywhere in Australia, you don't have to fit them but your home needs to meet a mandated minimum '6 star' energy rating. This comes down to everything in the house such as wattage per square meter of lighting, double glazing in windows etc.

The biggest pitfalls here usually with solar hot water is the storage capacity, especially with a family.

Americans are afraid of the "third-world look" of solar water heaters they know from vacations in Europe

I don't think this is true? Also for what it's worth I've spent time on the roofs of a lot of apartment buildings in the bay area and seen many solar water heaters. Newer buildings and homes tend to just have solar panels if anything, though.

I guess I'm not privileged to have seen that and would mind a setup on my house. I'm in AZ

You can get hot water for way cheaper using solar hot water than PV. I can’t speak to the maintenance.

That's the thing - I think the economics have changed.

When it was first a thing - solar hot water was expensive and pv was very expensive.

Then I over time the prices dropped. Sites like https:://sunelec.com made me think... I could afford a pallet of panels... or a container!

Also, pv water heating wouldn't strictly require an inverter.

As to the maintenance, I recall the carter vs reagan white house situation.

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