Do you need a consumption meter to know your monthly (not real time) usage?

[petesamprs]

After installing solar, does your electric bill show the gross values of amount produced and amount consumed each month, or just the net? Trying to decide if I need a consumption meter. I don't need to track consumption in real time, but I do need to see at least what I consumed each month (on a gross basis) so I can keep a running calculation of how much I am saving and what my IRR is on the solar project.

[RichardCullip]

After installing solar, does your electric bill show the gross values of amount produced and amount consumed each month, or just the net? Trying to decide if I need a consumption meter. I don't need to track consumption in real time, but I do need to see at least what I consumed each month (on a gross basis) so I can keep a running calculation of how much I am saving and what my IRR is on the solar project.

My SDG&E bill only shows net usage so I have to do a bit of work to get the actual consumption values. On my SolarEdge system I track hourly solar production with an Excel spreadsheet and their API. I also download net usage from the SDG&E website. It's then a simple matter to add the two together to track total household usage. In my case, it can be done without a consumption meter and with a bit of Excel Macro magic it's almost automatic.

[J.P.M.]

If you have a meter to measure/record solar output and a meter to measure what comes in from/goes out to the POCO, you have the necessary tools to measure total usage.

I have both and, among other things, read/record solar generation and POCO meter data every 24 hrs. Also have several kill-a-watt meters to measure/keep an eye on various 110 V appliance usage as necessary.

[JSchnee21]

For what it's worth, my PoCo bill (JCP&L) displays both/everything:

Production -- Meter reading from prior month, current, and delta
Consumption -- Meter reading from prior month, current, and delta
and of course
Net -- Consumption Delta - Production Delta

You could of course read these values off your bidirectional PoCo meter every month, too. Or with whatever frequency suits your fancy.

I also have Solar Edge consumption monitoring, which, while over priced, is worth it's weight in gold in my opinion. To be able to see in near real time if my kids turned the air conditioner or bathroon heater on. All my production and consumption data in one App, reporting through the API to PVOutput.org

I'm very happy with mine.

[bob-n]

My power company installs an Itron "Netmeter", which displays and monitors current going into my breaker box (consumption) and current going from the breaker box into the grid (production). However, it doesn't see energy that comes directly from the inverter to the house loads. That current travels from the inverter into the breaker box and right out of the breaker box to the loads, without ever flowing to the meter.

To get a full picture, you may need something else that you will purchase, like the Solar Edge monitor that other have described.

[DrLumen]

It depends on your utility bill. Mine shows what I used from the grid and what I put out on the grid. Using these along with the data from SE of what I generated I can get my consumption.

[petesamprs]

Thanks all. I'll check with my PoCo how they show my information.

I thought that all production was exported into grid and all consumption was imported from grid. I didn't realize that my real time solar production can also be applied to my real time consumption without first going into the grid. If that's the case I'll need to also track that data in addition to what my PoCo provides.

[J.P.M.]

My SDG&E bill only shows net usage so I have to do a bit of work to get the actual consumption values. On my SolarEdge system I track hourly solar production with an Excel spreadsheet and their API. I also download net usage from the SDG&E website. It's then a simple matter to add the two together to track total household usage. In my case, it can be done without a consumption meter and with a bit of Excel Macro magic it's almost automatic.

If your meter is like mine, it also cycles through a bunch of stuff ~ every 45 sec., including what I've sent to the grid and what I've received from the grid. Those two tare readings and the total meter tare between two dates or times along with the data on production from the PV monitor that's been corrected to match the POCO meter gives me reasonably accurate info on things such as how much of the PV production gets used internally and never sees the grid.

Maybe the OP has a meter and a PV monitor that does similar.

[RichardCullip]

If your meter is like mine, it also cycles through a bunch of stuff ~ every 45 sec., including what I've sent to the grid and what I've received from the grid. Those two tare readings and the total meter tare between two dates or times along with the data on production from the PV monitor that's been corrected to match the POCO meter gives me reasonably accurate info on things such as how much of the PV production gets used internally and never sees the grid.

Maybe the OP has a meter and a PV monitor that does similar.

Something else for me to learn how to do. I currently have access to my SDG&E SmartMeter thru my home area network using an Eagle 200 device from RainForest Automation. I wonder if I can read the tare readings you reference from the comforts of Excel or if am I restricted to going outside and physically reading the meter display. Time will tell.

[J.P.M.]

Something else for me to learn how to do. I currently have access to my SDG&E SmartMeter thru my home area network using an Eagle 200 device from RainForest Automation. I wonder if I can read the tare readings you reference from the comforts of Excel or if am I restricted to going outside and physically reading the meter display. Time will tell.

Don't know. I've been doing so much for so long with so little in the way of electronics, I now feel qualified to attempt just about anything with no more than a pencil and paper, and then transferring the data to a spreadsheet.

I will admit to adding to the world's supply of unprocessed data with the 5 minute output from the array monitor and the 1 minute output from the Davis weather station.

I believe the "received from" and the "sent to" energy data viewable from the POCO meter can easily be found in the 15 minute data from SDG & E.

I just read/record the numbers from the meter 1X/day as part of the daily ritual that's been going on since the mid '70's in one way or several, and then spreadsheet the data, at first manually, then w/ FORTRAN and the BASIC, then Lotus 1-2-3 until Excel came along.

I believe I've got consumption, production and array performance dialed in pretty good. Different strokes.

[DrLumen]

Thanks all. I'll check with my PoCo how they show my information.

I thought that all production was exported into grid and all consumption was imported from grid. I didn't realize that my real time solar production can also be applied to my real time consumption without first going into the grid. If that's the case I'll need to also track that data in addition to what my PoCo provides.

I think it is referred to as self-consumption. Technically, when you are producing power and using it, you are pulling from your array and the grid simultaneously as they are set in parallel in a typical system. You just aren't pulling as much from the grid. It is likely half-and-half if your consumption is equal to what you are producing at that moment. But, in that instance, the other 'half' is going to the grid. Since it is parallel there is really no way to only self-consume without transfer switches. On a logical level, you can consider it as all self-consumption if you are using what you are producing at that instant.

This is where I learned to use as much as I can during the day while producing. I only get a few cents for producing but pay 11-12 cents for grid power.

[Ampster]

........Technically, when you are producing power and using it, you are pulling from your array and the grid simultaneously as they are set in parallel in a typical system. You just aren't pulling as much from the grid. It is likely half-and-half if your consumption is equal to what you are producing at that moment. But, in that instance, the other 'half' is going to the grid. .......

Not really, production will go to your consumption first and anything left over will be sent through your meter to the grid. They are indeed parallel but physics determines that your production goes to your consumption then to the nearest transformer which might feed you neighbors first before it goes to the grid. Electrons flow to the shortest path.

[DrLumen]

Not really, production will go to your consumption first and anything left over will be sent through your meter to the grid. They are indeed parallel but physics determines that your production goes to your consumption then to the nearest transformer which might feed you neighbors first before it goes to the grid. Electrons flow to the shortest path.

It would depend on the wiring of your service from the PUC. The only slight difference would be equivalent to the transmission loss via the grid. I would be surprised if it were any higher than 2 or 3 percent difference from the transformer to your house.

[petesamprs]

Thanks all. I'll see what info my meter shows. I won't be checking in daily like some people, but if I can see the running data every few weeks that I will give me what I need. Either that or the bill itself. But either way I need some way (ideally monthly) to know my gross consumption to determine my $ savings from going solar (without considering changes in behavior from energy being "free")

Something else I can't figure out:
If some (or all) of my production is being used in real-time without ever going back into the grid, why won't solar work to power my house during a blackout? I'd like to better understand how the wiring works between my utility meter (outside), breaker box and inverter. If the inverter is wired to the breaker box in order to be able to use my real-time production, won't the box be "hot" even during a power outage? Can't you keep the box "hot" with solar but just shut off the mains so that energy is not being fed back into the grid? At my prior house I had a generator hookup into my main breaker box, and installed an interlock to ensure that the generator's circuit was only able to be on when the main breaker was off: https://www.interlockkit.com/

[Ampster]

Something else I can't figure out:
If some (or all) of my production is being used in real-time without ever going back into the grid, why won't solar work to power my house during a blackout? I'd like to better understand how the wiring works between my utility meter (outside), breaker box and inverter. If the inverter is wired to the breaker box ireal-time production, won't the box be "hot" even during a power outage? Can't you keep the box "hot" with solar but just shut off the mains so that energy is not being fed back into the grid? At my prior house I had a generator hookup into my main breaker box, and installed an interlock to ensure that the generator's circuit was only able to be on when the main breaker was off: https://www.interlockkit.com/

Your inverter would need batteries and additional hardware to do that. It has been designed to only sync with the grid, hence the name, Grid Tie Inverter. Hybrid inverters can do that but are more expense because of the addition hardware, software and UL certification.