Self-Consumption of PV power: grid tied, no net metering, no batteries

[Ampster]

Not looking to hijack here. I'll just toss this out as an example.

I am currently self-consuming 7kW here but it is not a commonly know application or an off the shelf known piece of equipment.
It is a system of load diversion that redirects any surplus PV production beyond consumption by way of a zero crossing SSR relay(s) or triac driven by a Arduino-like board with current transformers monitoring the current direction and is able to match ever changing current amount available for export and then switch that precise current amount to whatever load(s) I chose as my output(s). Which is currently into a super insulated 110 and 80 gallon water storage tanks with 4 independent conventional 240VAC resistance heater elements...2 per each tank. In my application I have the four circuits in priority steps and the diversion process happens in sequence moving from 1 thur 4 as hot water demand and PV surplus production dictates.
Water is just another medium of a storage battery. Enough for now.

Actually, I think that is on topic of the title of this thread which is about self consumption. I am intrigued about that Arduino application

I currently use IFTTT to increase the temperature of my heat pump water heater when the output of my solar gets to 1000 Watts. The solar output is measured by a CT clamp connected to a Neurio which which can trigger a IFTTT action. My next project is to trigger a relay to run an outlet to one of my car chargers to soak up some of the solar energy. I am on NEM but I already have a big enough credit I am better off using some production rather than pay non Bypassable Charges when I consume energy.

[neweclipse]

Not looking to hijack here. I'll just toss this out as an example.

I am currently self-consuming 7kW here but it is not a commonly know application or an off the shelf known piece of equipment.
It is a system of load diversion that redirects any surplus PV production beyond consumption by way of a zero crossing SSR relay(s) or triac driven by a Arduino-like board with current transformers monitoring the current direction and is able to match ever changing current amount available for export and then switch that precise current amount to whatever load(s) I chose as my output(s). Which is currently into a super insulated 110 and 80 gallon water storage tanks with 4 independent conventional 240VAC resistance heater elements...2 per each tank. In my application I have the four circuits in priority steps and the diversion process happens in sequence moving from 1 thur 4 as hot water demand and PV surplus production dictates.
Water is just another medium of a storage battery. Enough for now.

[evolknuj]

that is an option as long as you understand that it is not the most financially viable.

Yep -- IMHO still financially viable, just not the most financially viable. Thanks for all your help and quick responses to get me to understand!

[ButchDeal]

Yes, I think I understand that, but I think I do want interconnection as I don't think I will always be able to self-consume everything I generate -- summer months possibly, but not other times.

Well that is the thing. the inverter will cut back production such that it is not over producing if consumption drops at any instant.

So I could size for a smaller system, say 5kW installed, so that I'd have more likelihood of being able to consume it all myself all the time (or at least most of the time). But I'd rather have 15kW and be able to actually offset essentially all of my electricity carbon footprint on average, even if it doesn't actually zero out my electricity bill due to my POCOs somewhat asinine metering scheme. I'm not sure how small I'd have to go to reliably self-consume most of the time, 5kW was just a guess.

that is an option as long as you understand that it is not the most financially viable.

[evolknuj]

I can do anything I want behind the meter ( ie, no interconnection to the grid) as long as I use UL certified equipment pursuant to a building permit.

Yes, I think I understand that, but I think I do want interconnection as I don't think I will always be able to self-consume everything I generate -- summer months possibly, but not other times. So I could size for a smaller system, say 5kW installed, so that I'd have more likelihood of being able to consume it all myself all the time (or at least most of the time). But I'd rather have 15kW and be able to actually offset essentially all of my electricity carbon footprint on average, even if it doesn't actually zero out my electricity bill due to my POCOs somewhat asinine metering scheme. I'm not sure how small I'd have to go to reliably self-consume most of the time, 5kW was just a guess.

[Ampster]

........... Seems Austin Energy doesn't want me to do that.

Of course they don't. They make more money doing it their way. They aren't going to tell you that it is okay either. However if you understand what ButchDeal is saying, you don't have to ask Austin Power unless they have some special arrangement with the building department that requires Austin Power permission. I know for sure in my county in California that I can do anything I want behind the meter ( ie, no interconnection to the grid) as long as I use UL certified equipment pursuant to a building permit.

[ButchDeal]

Yeah, I'd found that document before and was hoping I could do exactly what was shown in Figure 1 with my POCO -- import and export still, as needed, but self consume as much as possible with the POCO meter completely unaware (not that I'm trying to "trick" the meter or bypass it or something, I just want to be able consume what I produce without being charged extra for it). Seems Austin Energy doesn't want me to do that.

Figure one is a general Net Meter configuration with the addition of a consumption meter.

you can do it but can not export without a net metering agreement.

[evolknuj]

yes if you have a consumption meter configured.

https://www.solaredge.com/sites/defa...ation_note.pdf

Yeah, I'd found that document before and was hoping I could do exactly what was shown in Figure 1 with my POCO -- import and export still, as needed, but self consume as much as possible with the POCO meter completely unaware (not that I'm trying to "trick" the meter or bypass it or something, I just want to be able consume what I produce without being charged extra for it). Seems Austin Energy doesn't want me to do that.

[ButchDeal]

Does my HD Wave inverter have a setting for self consumption? I thought it only worked in Grid Tie mode? I know my Outback inverter can be configured for Grid Zero (self consumption)

yes if you have a consumption meter configured.

https://www.solaredge.com/sites/default/files/feed-in_limitation_application_note.pdf

[Ampster]

Does my HD Wave inverter have a setting for self consumption? I thought it only worked in Grid Tie mode? I know my Outback inverter can be configured for Grid Zero (self consumption)

[ButchDeal]

Gotcha -- I'm still learning the terminology, grid-zero not-equals off-grid.

Grid zero just means not feeding power into the grid and is definitely not off grid.

I think POCO means POwerCOmpany, but only 90% sure .

PoCo is Power Company, yes

I wouldn't get the Austin Energy rebate for such an install, not _sure_ if I would qualify for federal tax credit (probably would)... and of course I would prefer a larger system for personal satisfaction (carbon offset) even if it's not 100% optimal financially. But it's a good point / option for others in the same scenario.

Yes you would still qualify for the Federal Tax Credit

Does that suggest that if Austin Energy changed their policies at some point in the future, whatever system I install (lets say SolarEdge HD Wave inverter) could be reconfigured, perhaps with the addition of the SolarEdge consumption meter box, to allow self-consumption before the meter, but also supplement from the grid when production is not sufficient and feed back to the grid when production is too high?

In a grid zero situation, the inverter would TRY to provide all the power that the house is using and no more. There is no physical limitation on the power just the electronics trying to regulate the inverter such that the consumption is zero. IF you are consuming more than the inverter can produce, it will come from the grid.

If the PoCo changes their policy it is just a software configuration change to the inverter to allow it to net meter as regular though it would require a net meter application (documents) with the PoCo.

[evolknuj]

Gotcha -- I'm still learning the terminology, grid-zero not-equals off-grid. I think POCO means POwerCOmpany, but only 90% sure . I wouldn't get the Austin Energy rebate for such an install, not _sure_ if I would qualify for federal tax credit (probably would)... and of course I would prefer a larger system for personal satisfaction (carbon offset) even if it's not 100% optimal financially. But it's a good point / option for others in the same scenario.

Does that suggest that if Austin Energy changed their policies at some point in the future, whatever system I install (lets say SolarEdge HD Wave inverter) could be reconfigured, perhaps with the addition of the SolarEdge consumption meter box, to allow self-consumption before the meter, but also supplement from the grid when production is not sufficient and feed back to the grid when production is too high?

[ButchDeal]

Yeah, with current battery costs I think it's prohibitive for the rates I'm working with -- my top tier rate is less than half of some numbers I've seen out of Hawaii. Going entirely off grid wouldn't be an option for me. I'm not sure about "illegal", but it's certainly annoying that AustinEnergy wants to prevent self-consumption, or at least wants to meter separately and have me pay for self-consumption. I would have thought they'd be fine with people actually reducing their dependence on the grid... but I'll be doing attic insulation / radiant barrier improvements to help with that too.

They are not PREVENTING your self consumption but why I say it is illegal is that self consumption is still happening, but they are charging you for it.

as I mentioned a smaller solar system set up east/west can be configured for grid zero (no feed in) with just the addition of a consumption meter and configuration change. You then would not need an interconnect. It would not be as much savings but would also not be as much cost.

[evolknuj]

Yeah, with current battery costs I think it's prohibitive for the rates I'm working with -- my top tier rate is less than half of some numbers I've seen out of Hawaii. Going entirely off grid wouldn't be an option for me. I'm not sure about "illegal", but it's certainly annoying that AustinEnergy wants to prevent self-consumption, or at least wants to meter separately and have me pay for self-consumption. I would have thought they'd be fine with people actually reducing their dependence on the grid... but I'll be doing attic insulation / radiant barrier improvements to help with that too.

[ButchDeal]

And that would only require a building permit if no interconnection was requested. Just to be clear that also assumes UL approved equipment in order to comply with codes. No permission needed from the POCO since everything is behind the meter.

absolutely right.

This can be done with most grid tie inverters as well as all of them from SolarEdge and enphase. Consumption meter is required and configuration change for grid zero.
A smaller array would be set up and best if you can get east and west modules (longer production day).
A battery would allow more self consumption but at higher cost.