# Forum Home Renovation Solar Electrical Systems  Boost Gas Hot Water with Solar?

## lwright

Hi Folks, 
I've been looking into getting solar hot water but I'm not sure if I might be better off diverting some of our excess solar PV towards water heating.   We have a 6kw PV system that exports about twice the electricity we actually use.   We also have a 170L gas hot water system.   I'm not sure if there is a spare socket where I could add an electric element.   I can't see one.    Alternatively maybe it could be better to add a second tank to pre-heat the water going into the gas system but it sounds a bit more complicated.     We're spending about $700 a year on gas but that includes the stove top (but the oven is electric).    
Anyway appreciate any ideas.

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## Uncle Bob

I guess you'd ned to replace that gas service with an electric one. I think doing so would pay for itself fairly quickly.

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## Bart1080

You could be eligible for one of those heat pump hot water replacements.
Be interesting how long they last.  If you replace it with a 170l, generally its free.  https://www.victorianenergysaver.vic...7ek5yOZ7GiIGwQ 
Other than that, buy a new electric hot water tank or second hand one off something like Gumtree.
I'd bought one off gumtree for $80,  8 years ago and still going strong...replaced the element in it once. 
I've put solar on the roof 12Kw and doing the same with heating up hot water
I've also got a 2 flat panel solar hot water panels connected and whilst they are expensive to buy new, there are plenty of cheap ones off Gumtree if you keep an eye out as everyone is either putting up solar and need the roof space or told the flat panels are inefficient and converting to vacuum tubes.   
Dont be sucked in with the inefficient talk as the performance difference in Spring/Summer/Autumn months is minimal and definitely not worth the "replacement" costs which would take years to pay back you replacement outlay.  The good news is you can pick up a good secondhand 2 x flat panel system super cheap <$200.  If you head down this path, let me know as I'II take some picks of a mod that virtually eliminates the failure of the frost valves due to excessive heat.

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## lwright

Thanks.  I could I guess but I do like the idea of a having a diversity of energy sources though.    If the mains electricity goes out then we're out of hot water.  We're in regional NSW & it does happen a bit.

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## lwright

> You could be eligible for one of those heat pump hot water replacements.
> Be interesting how long they last.  If you replace it with a 170l, generally its free.  https://www.victorianenergysaver.vic...7ek5yOZ7GiIGwQ 
> Other than that, buy a new electric hot water tank or second hand one off something like Gumtree.
> I'd bought one off gumtree for $80,  8 years ago and still going strong...replaced the element in it once. 
> I've put solar on the roof 12Kw and doing the same with heating up hot water
> I've also got a 2 flat panel solar hot water panels connected and whilst they are expensive to buy new, there are plenty of cheap ones off Gumtree if you keep an eye out as everyone is either putting up solar and need the roof space or told the flat panels are inefficient and converting to vacuum tubes.   
> Dont be sucked in with the inefficient talk as the performance difference in Spring/Summer/Autumn months is minimal and definitely not worth the "replacement" costs which would take years to pay back you replacement outlay.  The good news is you can pick up a good secondhand 2 x flat panel system super cheap <$200.  If you head down this path, let me know as I'II take some picks of a mod that virtually eliminates the failure of the frost valves due to excessive heat.

  Thanks.   If I was going to go for hot water panels then I had been thinking of vacuum tubes since it gets quite cold here (Orange, NSW) but you're right about the flat panels being quite cheap used.   I'd get a plumber to install & I'm sure they have used tanks by the dozen.

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## Moondog55

Many years ago I made a very simple preheater for my HWS. I bought some black plastic polypipe, some flat foam panels and a few sheets of clear roofing. 
Made a quick frame from cheap pine laid the foam on the roof [ rental flat above a shop and flat concrete roof with bitumen WPC] put the coiled pipe on top of the foam insulation inside the pine framing and laid the clear roofing on top. Did a quick and dirty plumbing connection to the HWS entry.
Even on a cold winters day in Melbourne there as a surprising amount of heat developed and on a hot summers day the water was damned hot. 
Not my original idea; such solar preheaters are or were very common a few decades back. They are cheap and very effective; save a lot of money if your HWS runs on LPG when the wood stove isn't being used.

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