I have a question regarding the accuracy of Smart Meters. We get a daily email that has a chart showing our electricity usage, which is apparently reported by the smart meter every 15 minutes. When reviewing this chart, I'm able to see energy "spikes" around the times I would expect, such as getting up in the morning, arriving home after work, preparing dinner, etc. However, on some days, the chart shows a huge spike that happens around Midnight, where the usage is showing to be 2-3 times higher than the highest usage times during the day. Yesterday's chart showed that we used 1.5 kwh between 11pm-Midnight, the next highest for the day was 0.65 kwh between 6am-7am, which is when the entire family wakes up to get ready for school/work. The rest of the day, it hovered between 0.2 kwh and 0.5 kwh. We were all in bed and everything was turned off by 11 pm yesterday.

This spike doesn't show up on every day's chart, but it shows up often enough to wonder WTH is going on. Part of me wonders if the Smart Meter really only takes a truly accurate measurement around midnight each day, hence the spike happening in the last hour of the day as it is trying to "catch up" were is under-reported during the day, and is just approximating the readings the rest of the day.

Can anyone offer any explanation for this? Is there anything I can do to monitor or test this myself?

TIA

I know that they do take readings every x minutes, not once per day. There shouldn't be a catch-up amount. What large electric loads do you have at your house?

Your hypothesis about the meters function isn't correct. They are measuring digital data pulses in real time that would be somewhat equivalent to thinking about the revolution of the disk of an older mechanical meter equaling "a pulse". Those pulses/revolution equivalents are collected in real time and then summed for each 15 minute interval to be consistent with the norm for commercial and industrial customers of measuring demand on a 15 minute interval basis.

Given your description the first thing I would ask would be when does your dishwasher typically run and do you have an electric water heater? Or does someone wash clothes late in the evening and then throw the load in the dryer somewhere around 11 pm on those nights it happens? A 4500 watt clothes dryer element running for 20 minutes would be just a little shy of 1.5 kWh.

Electric water heater? A/C? Heat pump? Pool pump?

Nm, it's all controls.

I'd look at the overall consumption for the billing cycle and compare it to last year.

Lone Ranger, I think you hit the nail on the head. I put a load of laundry in our electric dryer right before going to bed at 11pm last night, which must account for the spike.

I feel pretty dumb for having not thought of that!

I've always had a gas dryer prior to buying this house and didn't even think about it. We considered installing a gas line for the dryer, but with a $1k-$2k price tag to install the line I didn't feel it was worth the investment. Especially since the sellers left behind a nearly brand new high capacity electric dryer.