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dadio917
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Discussion Starter #1
Wondering if anyone makes an element that can be added to a water heater to use excess energy from solar to keep water hot. Seems to me it doesn't have to be fast. Often my batteries are topped up with many hours of daylight left. Be nice to use that to heat some water.
 

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Many solar (& wind gen) panel controllers will have automatic LOAD switching. Such will auto-disconnect the batts when at FULL charge and will switch the LOAD to a heater tank 12vdc immersion heater. When the batts become at less than full charge, the controller switches back to keep the bank at 'full' charge.
 

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Many solar (& wind gen) panel controllers will have automatic LOAD switching. Such will auto-disconnect the batts when at FULL charge and will switch the LOAD to a heater tank 12vdc immersion heater. When the batts become at less than full charge, the controller switches back to keep the bank at 'full' charge.
Can you point to a few examples of those that can do?
Programed?
 

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I'd rather rig a relay off a proper SoC meter, start shedding when bank gets above 85%.

The SC usually has no ideas about what's going on with concurrent loads.

But also needs a time element, want to keep it off if only three hours of sun left and not yet over 90%.

Maybe best to just trip a notification and let the human decide.

Or get into Science Project mode with Arduino coding.
 

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Master Mariner
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As a full time liveaboard with the normal number of electric/electronic devices in use much of the time, at anchor or underway, I've never seen my batteries with enough charge to want to dump the charging by the solar and/or windgen. The batteries will settle to around 13.85v after the solar charging has ceased and drop to around 12.6/.4v before the sun comes up, if there's not enough wind for the windgen to produce any real power overnight (less than 5 amps total for the whole night).
You might want to be sure you are actually going to be producing enough excess power to need the dump to heat water or a resistive load before you spend the money and time to install something.
 

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dadio917
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Discussion Starter #9
Capta...how much battery and solar do you have?

We have 560AH of battery. Since we have an engine driven fridge with a big cold plate and all leds we have very little load on batteries at anchor for 2-3 days at a time. But.....am planning on switching to a 12v fridge for convenience of not running engine every few days and better temp control. Also planning on upgrading solar for 170W of very old panels to 240W of new more efficient cells. In that process am wondering if I should do something about water as well.
Thanks
 

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Wondering if anyone makes an element that can be added to a water heater to use excess energy from solar to keep water hot. Seems to me it doesn't have to be fast. Often my batteries are topped up with many hours of daylight left. Be nice to use that to heat some water.
I have more then enough power to do that. However, I'm a bit more pragmatic and maybe lazy too. I just put a jug on the stove and fire it up. Propane way easier, cheaper and faster.
 

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Capta...how much battery and solar do you have?

We have 560AH of battery. Since we have an engine driven fridge with a big cold plate and all leds we have very little load on batteries at anchor for 2-3 days at a time. But.....am planning on switching to a 12v fridge for convenience of not running engine every few days and better temp control. Also planning on upgrading solar for 170W of very old panels to 240W of new more efficient cells. In that process am wondering if I should do something about water as well.
Thanks
With 240 watts of panels you will receive a maximum of 16.66 amps assuming no shading and a good MPPT controller. Expect 5 to 6 hours a day at this output depending on location. With the addition of 12 volt refrigeration consuming 50 AH every 24 hours plus other on board usage you will not have excess current from the panels. A full charge takes many hours. It is doubtful you will reach full charge very often.
 

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Capta...how much battery and solar do you have?

We have 560AH of battery. Since we have an engine driven fridge with a big cold plate and all leds we have very little load on batteries at anchor for 2-3 days at a time. But.....am planning on switching to a 12v fridge for convenience of not running engine every few days and better temp control. Also planning on upgrading solar for 170W of very old panels to 240W of new more efficient cells. In that process am wondering if I should do something about water as well.
Thanks
As we have electric cooking and refrigeration (generator average: 2 hours a day (365) of 8kw), we haven't really built up much of a house battery bank, only about 400 amps. Our solar is 2 X 225 watt panels.
Were we to change over to propane cooking we would (money gods willing) like to go to 800 amps of 24 volt Li, with the appropriate renewable charging however, we would not get rid of the generator.
 

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Sunshower. Cheap, no electronics, no moving parts.
The heating element has no electronics, no moving parts, and is cheaper than a Sunshower.

The OP has an existing heater tank and excess solar that would go to waste if not diverted to heating water. If there is no sun, then there is no hot water from either the tank or the Sunshower. If there was sun yesterday but not today, the water in the tank is still warm, while the water in the Sunshower is cold.

A Sunshower is a bad recommendation for the OP all around.

Mark
 

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If the batteries are frequently topped, the idea of a heat sink into the hot water heater is a great idea. Of course, that requires a smart controller too. The real trick is how could you have both the 110v element and the 12v. I think the best the 12v is going to do is get you a good start.
 

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I have a sunshower on the boat, never had a problem with it and it only cost me about $10 from Amazon. It holds about 5 gallons and gets to nearly 95 degrees on most summer days.

Gary :cool:
 

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OP's question: "I have an existing hot water tank and excess solar power. Does a 12V heating element exist where I could use that excess power to heat the water in my existing tank?"

Some responses: "Get a solar shower"

You guys are funny, but not helpful...

BTW, there are also combined 120Vac/12Vdc elements.

Mark
 

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Some people also dump their excess output to making ice or running a crockpot or a dehumidifier. Sure we can talk about what appliance to buy within a given category.

But it is also relevant to ensure the OP does actually have much excess solar; most people just take their controllers' word for it that the bank is full, when premature infloatulation is the norm.

And it is a valid question whether the heat produced by dumping excess loads (if any) are worth the efforts and risks of complicating their HW setup.
 

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Yep, and when the ambient temps are in the mid 80's wtf do I need hot water for? Hopefully the OP is in a tropical cruising location.
 
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....

BTW, there are also combined 120Vac/12Vdc elements.

Mark
That's pretty cool. Above my pay grade to know who to hook it up so that one circuit was not backfeeding the other. Perhaps these dual units already have a brain for that.
 
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