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post #61 of 66 Old 11-30-2017
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Re: Solar heating element for water heater

Thanks Mark. Good to know. Have 3 year old lifeline agms. Had them recently load load tested and they are still in the high 80- low 90% range so probably have a few more years left. Will wait and hopefully Li Metal will be available by the time they need replacing. Agree it will be a game changer.
At present the genset goes on so rarely itís become a service thing to turn it on once a month so it gets some use. So think our energy budget is ok. Neither wife or I like AC (in fact itís run more to heat than cool). Big wastes for us is music and movies on the flat screen. Have had multiple occasions to need the genset on passage as the AP chews up electrons.
Big issue is space. Constant battle to prevent bride from putting more stuff on the boat so rather have a kerig then a kettle but thatís a smart idea. Iím still looking for room for a diving hookah.

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post #62 of 66 Old 11-30-2017
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Re: Solar heating element for water heater

Originally Posted by outbound View Post
I donít know. Have spent several seasons in tropics. Seems we use a lot of hot water. Use it to wash greasy dishes. When showering in the morning or evening like water temperature the same as body temperature. Tank water is colder. After diving get cold so a hot shower is nice.
Also think never have enough electricity because always can use extra fresh water. If tanks are full itís time to turn on the TV or computer or charge all the devices.
Guess for me and I think most this whole discussion seems off target.
Know Iím not a full time live aboard but Iím am 7-8/12 month one. Only times Iíve had ďspareĒ power to think about doing this is the rare windy and sunny days when I donít have another need or desire. Would look forward to comments from others if they are in the same boat😀.
Interesting conversation all the way around. Looking at Mark's reply you guys do have a pretty big energy budget. I never considered water makers & running other stuff for life so there's not alot of energy to spare using PV. Mark's solution was to upgrade his house bank to Lithium & that makes sense if one can afford the intial investement. I looked into lithium for my propulsion bank. Despite all the benefits I just didn't want to part with the cash.

One thing that stood out to me based upon the above regarding hot water usage & I think this also plays into your electric usage. When we size domestic hot water systems for multi family housing demograhics come into play. Historical data has shown people that go to work use less hot water daily than people that stay at home. Maybe being retired/cruising one's hot water usage falls into the pattern of more. Using solar whether PV or thermal we rely on the solar system to charge a storage system be it a battery bank or water heater. Boat water heaters are small offering little to no storage capacity. Based upon ones hot water usage pattern, it would be difficult to rely upon solar of any type if water was being drawn during the day.

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post #63 of 66 Old 11-30-2017
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Re: Solar heating element for water heater

Just for clarity, we didn't have any problems with our previous FLA batteries and solar, so moving to lithium wasn't a solution for anything.

Our FLA batteries were near end of life, we had returned to the US for a year or two, and it was a convenient time and place to change to lithium before heading out of the US again.

Now that they are installed, they opened up other possibilities in energy usage, like running high-load AC powered stuff off of them. This was a bit unexpected, but much appreciated now. I'm convinced that if/when lithium or similar battery technology becomes more mainstream, there will no longer be battery or power threads on forums.

We don't use much hot water because we are mostly in the tropics. I rarely use hot water in the shower, although Michele always does. We have a 11gal tank, and it is much larger than we need. Even 6gal would be too large for just showering for us.


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post #64 of 66 Old 11-30-2017
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Re: Solar heating element for water heater

Just throwing this out there....

Sun showers are really nice but most of the ones I am familiar with are cheap crap and aren't made to hold up for 'years'.
Hey, they work and I love using them.

A black 'dry bag' is much tougher and will do the same thing...but w/o hose. Good dry bags are tough and will fold/roll down fairly small.

I've had sun shower water get too hot for a shower. It makes/stores hot water...very useful. Weight and space...collect when desired...
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post #65 of 66 Old 12-02-2017
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Re: Solar heating element for water heater

When we bought our boat it had one of those dual heating elements in the hot water heater. It's sounds like a good way to dump excess watts from the wind generator and solar panels when the batteries are full charged but the problem we found is that the
AC element is such low wattage that it took forever to heat the water up enough for a shower and we so rarely have excess DC power to spare that the DC element was almost never used. So I removed the dual element in favor of a higher wattage AC element but have kept the dual element aboard just in case priorities change if we ever make it to the tropics.

Someone already suggested it but I think a small icemaker would be a GREAT use for that excess power!
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post #66 of 66 Old 12-04-2017
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Re: Solar heating element for water heater

I installed a dual element in my hot water heater, bought from Hotwire. Zantrax controller diverts excess power above 14.2 volts to heater. works great with solar panal, but zantrax response time on gusty winds with wind gen leaves a little to be desired, if batteries are fully charged, I normally will turn off wind gen.
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