The Microcare solar geyser controller uses PV panels to heat the water instead of EV tube or flat plate technology. The advantage is that no plumbing is needed. Connect up to your existing geyser and start saving money from day one.
Ah, I missed that. I guess that it is a “grid-tied” inverter that can work without a grid. In this situation it is actually not that difficult - your load is resistive, so you only ever have to run in current mode. Essentially, the case where the grid is off is exactly the same control algorithm as when it is on.
If I had to guess, it probably has a simple boost converter, and since you can do MPPT with a boost converter as well, I would guess that’s what they did. It’s essentially an MPPT (like their existing range) that just goes the other way.
Anyway, that would be MY guess.
The panels probably has a Vmp around 45V, so this runs at 135V ish, at probably 10A or so, so maybe 1.4kW. You can then literally just run the converter for max power, there is not enough juice there to blow a standard geyser element.
1.4kW over 5 hours average peak sunshine, that’s 7kWh, which in my experience will heat around 120 to 150 liters of water. Standing loss not accounted for, so probably around 100 liters. In my house that won’t zero the bill… but it will halve it
@Solarphile Thanks for the feedback.
I trust that all advertising is good so it’s ok to discuss the issue?
I’ve always had a phobia about inverters and attempting to step up a voltage to a higher voltage. This is based on conclusions that I’ve drawn without sound reasoning.
What I would like is to do the comparison between the direct DC heater like mine and one of these inverter versions. I think a shootout like this would be interesting…
It’s fairly easy to do: If I had to go to the other site I would simply take my system with the dual element. On a clear day around midday would be ideal…
In that case it becomes a shootout between the two converters. I mean, if everything else is exactly the same (which they probably won’t be), or if you account for it somehow (which will be necessary).
What is unclear to me in this case is whether the higher-voltage one actually runs AC. @_a_a_a ? You know?
I heard somewhere that AC might in fact be the better option for the life of the tank. Not sure exactly, but I do know where electrical current flows, it creates am EMF field around the conductors and that can interact with corrosion of metal in the area. When you constantly swap the polarity that doesn’t happen.
The ceramic DC elements probably doesn’t have this problem. The coiled-up resistive heaters will be more susceptible. At least I would expect that to be the case.
Also, where inductive loads are concerned, the total impedance is actually R + X (where X is relative to the frequency), which means the device has a higher impedance when driven by AC. Garden irrigation 24V valves are like that. 24VAC is perfect, 24VDC will blow them up in the long run. But geyser elements are just about completely resistive, so not a factor here.
I have no idea, all of my comments are speculation. I must admit, from the image above it does not look like there are any inductors or space for inductors (although the image is unclear), so I might be way off the mark… Possibly it rectifies the incoming AC and just gives out DC to the element.
I actually suspect it is DC output but they make sure that the thermostat actually does not do the switching. The manual specifies to set the physical thermostat to maximum temp and then on the controller the “DC temp” is to be set 5° C lower than this.
Youtube video with better views of controller (and can hear the relays clicking when switching).
Btw @mmaritz maybe good idea to split the discussion out from the advert?