IoTaWatt success - quick return on investment

Just a note of thanks/success regarding my install.

My electric bill spiked by about $150 with no change in behavior. Some of that is seasonal but there was clearly something wrong. The house is from the late 1940’s but new to me and both it and the property are large, with a number of systems and some features that I’m not used to.

Purchased and installed the IoTawatt and found a failing sump pump within five minutes. The sump here has three pumps, so the overall system was working fine and it was not obvious that one pump was in distress. The pump was pulling several hundred watts 24/7 without actually working. Fortunately it was submerged at all times and not a fire hazard. Unplugged the seized pump and watched the wattage drop in real time.

Fantastic product!


Visibility is power and saves power; along with money. Great use case.

I had a similar situation here. I found a sump pump with a bad level switch that was running constantly and pulling 500 watts. It was keeping the sump pumped out but costly. I made proper set of float switches and a pump controller to replace the “dangle ball” type switch that had failed. That’s the second time one of these has failed. The first failed open and wasn’t pumping the sump down. That one became obvious pretty quickly. God knows how long the second failure went on before I installed the IoTaWatt.


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I just ordered an IoTaWatt system for the same reason. My electric usage as soared in the last few months with no apparent explanation, no change in our usage or habits. I have 8.5 kW of solar panels and they generally make 900 to 100 kWh a month depending on the time of year. Small house (less than 1400 sq feet) with two 10K BTU window A/C units we run during the hotter part of the day. Electric hot water heater, stove, dryer, and 1 HP pump for the pool. Somehow we managed to use 1600 kWh last month. Crazy! I can’t wait to find out what’s going on. Thanks for sharing your success story.!


That is a significant jump. It looks like you pay a lot for electricity wherever you are. It also looks like they probably charge you more for delivery than they pay you for your generation.

While the generation number for November looks low (355KWh), it is close to the number from last December, so could be accurate. The generation numbers for July to October look similar, so it appears that your solar panels are working okay. But, since they probably can only see your generation when your house’s load is less than what the panels are generating, it means that your excess usage is probably coming when it is dark. So, probably not the AC units. Looking at the numbers, I am seeing about 600-900KWh extra usage over 30 days. That is 20-30 KWh per day. If we assume it is a load on only when it is dark, that is a 2-3KW load (on for 10 hours). If we assume it is on 24 hours a day, that would probably make it 1-2KW. A 1HP pool pump uses around 1KW. Does it run all day/night? Has it always done this?

Is your water heater a heat pump one or conventional (resistance element). A conventional one is probably 13-20KWh/day (depending on usage). Are you using more hot water than before. A long hot shower can easily use 30 gallons of hot water and that can take 4-5KWh of energy to heat.

It will be interesting to hear what you find.

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Please pardon the typos in my earlier remarks. Solar PV monthly output is typically 900 to 1100 kWh. This past month has been more cloudy than usual (but not enough to explain 1600 kWh of consumption). If anyone is interested/curious you can view live info and history here:

Pool pump runs on a digital timer-- 20 min on / 20 min off from 9 AM to 3 PM so that’s 3 hours a day. Wife yells at me if I take too long in the shower so that’s not it either. :smile:

Here is the power usage chart from the prior year. Pushed out 583 kWh to the grid the previous November. You’re absolutely right-- it just reflects excess solar power not consumed on site.

The good news is USPS tracking says my IoTaWatt package will be here tomorrow… so I’m excited to get it set up and see what the heck is going on!

Quick update… the problem appears to be a hot water leak underneath the slab/foundation of my house. There’s actually a warm area on the tile floor (which sits directly on the slab). Not exactly “good news” but at least I have an explanation now.

So it wasn’t a long hot shower, but it is the water heater :wink:

Well now you can figure out how to fix it.

An infrared camera should help find the leak.

If you plot the last 24 hours and look at the data statistics, you’ll see the kWh used by the HWH in 24 hours.

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Gary from P&S Plumbing in Kailua Kona should literally be here any minute with his thermal imaging camera. :slight_smile: I extrapolated from the 17 hour sample and estimated HWH is burning around 34 kWh a day. Yikes. My 8.5kW (DC) worth of solar panels didn’t have a chance against that. 1600 kWh last month which I manually calculated by looking at my solar production for the same 30 days as my electric bill. Now the IoTaWatt will make that super easy. Money well spent. :+1:

Just set all this up yesterday. Snapshot of what’s going on at the moment. A/C is on in my garage office. :wink: