Yes!
These things are very scarce due to the dominant AC standard we have.
Hereās a possibility: NVF4-2aA-S40-DC12-1.6-aR *A* - AUTOMOTIVE RELAY SPST 40A 12VDC P/ON NO-CLIP
So cheap you can connect a few of them in seriesā¦
https://www.4x4community.co.za/forum/showthread.php/372332-Heating-water-directly-from-solar-panels?p=5231137#post5231137
Just to cheer up your day hereās another post from WWP.
I donāt agree with all that is claimed here but Iām just trying to hang on to the argumentā¦ (which isnāt a walk in the park!)
Eish. The more I read this guys posts, the more I think of a book:
There is no need to worry too much about voltage. You know the maximum current the panel provides in full sun. You want the same current as the element would normally pass on 230VAC.
If you pass 13 amps through the average 3kW element, it will have 230V across it. Now all you need to do is add enough panels so that your voltage does not drop below 230V too easily, and youāre done. You can add as many panels as you want past that, the voltage will always pull down to whatever ohms law dictate for that amount of current, so you are really just stopping one panel over this voltage because to do anything else is a waste of money 
If you add panels in series surely the voltage and current will increase??
Nope. Current stays the same. The current a solar panel makes is proportional to the incoming insolation. You can decide at what voltage you want to do the work, but the current maxes out at Imax, and at Isc (which is not much different) if you dead short it. Adding more panels in series just causes a drop in efficiency since the working voltage is dragged down.
This entire exercise boils down to finding panels that has an Imax at around the value needed for the resistive element in the tank, and then adding just enough of them to get the voltage high enough to do the work. The moment you get your current on the panel wrong, you need some kind of conversion interface to convert voltage to more currentā¦ ie an MPPT.
Of course there is some leeway in this, slightly lower current values just means it takes a bit longer to do the work, and vice versa. But in the end the voltage youāre going to end up with across the geyser element is the current the solar panels make multiplied by the resistance of the heating element, regardless of how many panels you add.
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So your only option besides impedance matching is to add another bank of identical panels and connect them in parallel?
Hereās a better option. Ok itās not new but it will work just fine.
What is interesting is that they specify the DC switching capability. (I presume this is for all poles connected in series)
PS: This is a great shop for those who are like myselfā¦
No, you can only go up to 3kW. After that you risk damaging the element in the geyser. What you want to do is install slightly over 3kWp of solar panels, and match the Imax of the panels to roughly what the element wants, which is around 13 amps. If you do that, the voltage will āautomaticallyā end up around 230V.