Jatho

Well I'll answer some of this since I've been living with 2 of these for the last couple of months and the savings for me were astounding but mostly because of a poorly thought out solar installation that was installed by the previous owner, let me explain... I have 3 phase power and use a lot of power for irrigation, water etc since we're off grid completely with water, previous owner was spending R5K per month for electricity and so were we when we first moved in. The main problem was that 6 of the 18 panels had major shading and would only start making any decent power from around midday so I added another 6 x 600w panels that get no shading which obviously made a massive difference. I then used these shaded panels (didn't move them) for the geysers, 3 per geyser, they're older panels so peak power is low at around 800w combined and voltage hovers between 115v to 125v, these Geyserwise units apparently cut off at 115V but I think its lower as I'm still getting temperature increase when its at 115w. The smaller 200l geyser now uses no Eskom at all and gets up to 70 degrees every day if I let it, the bigger 250l needs about 1 hour Eskom to suplement and get it up to temp, I am probably going to add 1 more panel for the bigger geyser and recon I'll then use no Eskom for geysers until winter. Before the change I'd run the 250l geyser which had a 1.2kw element for 8 hours everyday and the other 200l / 1.2kw element for around 3 hours ever day so its a considerable difference, I have changed these elements out for 3kw elements as their resistance is lower so needs a lower wattage to power the element. Since this change I'm spending about R500 on electricity so its been significant and the system will quickly pay for itself, I changed out the inverter for a single 12kw Deye, had 3 x Luxpowertek's in before which were junk. My only advise would be to rather spend an extra R200 per panel and go with 3 x 600w panels instead of 3 x 450w, they're pretty much the same size and it will make a huge difference to your performance and if budget allows 4 panels are even better. Calcs below from Geyserwise for panels vs elements. Specifications of Elements and Thermostats – Please see calculations for expected system performance All fixed resistive elements and thermostats are rated for connection to standard AC power., which is 230V with a sinewave frequency 50Hz. Connecting to a fixed AC resistive element without a MPPT will result in efficiency being compromised by ±40% in good conditions this can decline to as much as 60-70% in poor overcast conditions. Geyserwise has specifically designed the Geyserwise MWS with MPPT to effectively operate at maximum power efficiency of 99 % in the voltage range of 120 VDC to 350 VDC. Use the below formula to calculate the PV array to best match the performance of MWS with different size heating elements. P=Uvmp x Uvmp /R R = (12 -17 or 27 Ohm) 2 Kw = 2000 watts with a resistance of 27 Ohm 3 Kw = 3000 watts with a resistance of 17 Ohm 4 Kw = 4000 watts with a resistance of 12 Ohm If a 550-watt panel array is used with specification below: 550 Watts 41.7 Vmp 13.20 Amp 49.6 Voc. The panel maximum current must be below 15 Amp. Use a minimum of 3 panels in series UVmp = 3 x 41.7 = 125.1 UVmp x Uvmp = 125.1 x 125.1 = 15650 On a 2 Kw element 15650/27 = 579 watts at peak. On a 3 Kw element 15650/17 = 920 watts at peak. On a 4 Kw element 15650/12 = 1304 watts at peak The lower the resistance the better the performance. Results of connecting four panels in series: On 2 Kw element 27822/27 = 1030 watts at peak On 3 Kw element 27822/17 = 1636 watts at peak. On 4 Kw element 27822/12 = 2318 watts at peak.

If you're wanting to measure your whole homes consumption you should look at the Efergy energy meter although these are a fair bit more (R1000+) but they're easy to install and has quite a nice interface with reporting and logging.

Ah ok with you now... Would you need a device that could manage those amps for what you're wanting to do though?

I think a much more practical and probably easier way to do what you're wanting is to use a Sonoff POW and wire it inline with an extension lead that way you just plug one side of the lead into the wall socket and the other into the appliance / device you want to measure the load on.

Wow great effort man I never would have thought about replacing with an ESP module, I suppose not an open heart surgery everyone would be comfortable with but definitely worth giving it a go if you have good soldering skills and can flash ESP modules, really like that the power monitoring works as well (and this module is rated to comfortably handle geyser loads)

The Sonoff with external really is a good option and not too much of a hack to put together, did it for my geysers about a month ago and was very worthwhile has definitely made a difference with my consumption, all in I think it cost me about R475 per geyser.

Nice thread, your usage is very low do you not have things like electric geysers, oven, pool pump etc?

What do they cost? I think its unlikely that it works in Home Assistant would most probably only work with their app. Nothing comes up for Home Assistant CBI

I'm also resurrecting this thread but not by 4 years 🙂 I have / had mostly 12V downlights in my house and got tired of replacing transformers all the time some of which were in really difficult to reach places in my ceiling, I was also always under the assumption that they used a lot less power than standard light bulbs, boy was I wrong! I did a test a few months ago and flipped the switch to my entertainment area which has about 10 of these 12V downlights and was astonished to see that it drew 500w!! They're on a dimmer and draw came down to about 200W when they were dimmed (so perhaps dim the bathroom lights). Anyway, I laid out the cash for new dimmable LED bulbs and fittings where needed and replaced almost all of the 12V downlights, it made a significant difference to my consumption, I think all in I have about 40 downlights and have replaced 30 of them. In terms of lighting I've noticed no difference in my bathroom between the 12V's I had before and the new LED warm white bulbs, if anything I prefer the LED lighting.

Was wondering when someone would post about the update Its awesome problem with the GX is its pretty slow and a little annoying that you have to rotate the screen to landscape and can only allow access from one device at a time. The new VRM portal gives you all of that info in a much cleaner look along with some additional fields which is great, also love how it now displays your production and consumption as well as the utility usage for the stipulated period. Wonder if they'll give the GX the same face lift

Thanks for the pointers, My geysers and oven are connected through a Carlo Gavazzi energy meter so when mains fails power is cut to these devices anyway, I also have other automation's that detect mains failure and cut power to things like my pool pump, toasters, kettles etc... I've got it pretty streamlined to the point where if we have load shedding during the day my batteries usually charge up to 100% because the load is that low (around 260w) I actually end up manually just switching the pool back on, I also only start things like the pool pump if mains power is available, if it isn't it waits until it is.

Hi, Yes I'm using the exact same cable (gauge etc) as would be used from a DB board to Geyser between the relay and geyser, cable to and from the Sonoff is regular stranded electrical cable.

I cant imagine that it would get very hot, its rated at 40A so its running well below its threshold, I'll let it run for an hour today and then go measure the temp with a probe, I have spare temperature sensors so if I feel ambitious I could wire one up to the GPIO pins on the Sonoff and monitor the temperature inside the box. This geyser is installed outdoors so it needs to be in an IP6X rated enclosure.

Thanks for all the advice guys, version 2 is done, tested and working as it should just need to wire it in, was a pretty tight fit in the box 🙃

Thanks @Bloubul7 I did think of doing it based on temp (and time) but to be honest if I stagger the geysers coming on I've got plenty of capacity to power them and in my setup I think temperature control will have only marginal savings so just not worth the extra effort and cost for me, my main goal is just to ensure the geysers aren't pulling max draw at 6:30am and smoking through Eskom power (and eating into my battery capacity in case we get load shedding). I have a lot of automation's based on temperature.