Appreciate your feedback and insights as usual RegGuheert!
Envoy's and metering
RegGuheert said:
The cost difference is nil, but the old Envoy has a display while the new one does not. A small thing, but something. OTOH, the new one has a better warranty.
Good point. In my case I don't anticipate visiting the display in the garage regularly (though it'd certainly be nicer to have it than not for quick sanity checks). As long as both have the local API I can query for basic production status, then I'll be polling and graphing that info myself.
RegGuheert said:
ltbighorn said:
While it'd be nice to see my own consumption data, I'm not a fan of depending Enphase to feed it to me on terms I'd like. Getting a Rainforest EAGLE ZigBee gateway that pulls data from the Smart Meter seems to make more sense in terms of wiring (none) and data independence -- can this data be imported into Enphase's site, or something similar to get a whole-house view?
Thanks! I didn't know about this option. Here is
the link to the RainForest Automation website. So you mean that the radio on my meter is completely open and can be read by anyone? Interesting... I wonder how the power company reads it. Through PLC, I suppose.
Yes, that'd be the one. The radio is secured, important as it's considered to have personal behavior revealing data. You need the utility to approve and enable access from your device. With PG&E, as long as it's an approved (certified?) device, that's no problem.
They already have a revenue grade meter installed, so why not, eh?
RegGuheert said:
To answer your question, I seriously doubt that you can import it into Enlighten. That is part of Enphase' business model (owning the data). I don't know about third-party options, but I'm interested to learn more about this from you or others.
I think PVOutput ( http://pvoutput.org/ ) may be the third-party option I was thinking of. With an open API and a lot of auto-uploaders, I believe it can automatically pull the production data from the Enphase Enlighten API, as well as an Eagle Rainforest account (or Wattvision, if you get that version), to generate a net consumption view.
Here's an example from someone at solarpaneltalk, showing consumption and production, both real-time and cumulative for the day. I don't think temperature and voltage are actually being graphed -- not sure if that can be pulled from Enlighten if you have Manager access, or if it has to come from another input source.
And live version: http://pvoutput.org/intraday.jsp?id=34829&sid=33867&t=0&gs=3&s=1
AC batteries/future proofing
RegGuheert said:
ltbighorn said:
It seems like the Metered model would mainly be of benefit for someone who planned to take advantage of Enphase AC batteries, as it would allow the system to understand the load side of things and thus optimize battery charge/discharge patterns.
Agreed, but as someone who lives in CA, you should take that into consideration. Net metering will certainly come under fire from your utility sooner rather than later. Definitely within the 25-year life of your system. As such, the AC batteries are something you may have need of before you would like. If the Envoy-S with metering is a requirement for the AC Battery, then you really might want to consider springing for that.
Hmmmmmmmm. I do imagine it will come under fire, though with 20-year grandfathering on NEM 1.0 it'd probably be primarily in the form of TOU rate shifting. On NEM 1.0, as long as a non-TOU plan was offered, I would have that option as a fallback. With my system I'd always be low in the lowest tier on a non-TOU plan.
Right now the battery prices look to be pretty extreme, aside from the space costs & safety risks. Obviously battery prices will likely come down dramatically over the next 5-15 years, but I wonder whether I might not end up having to replace the Envoy-S over that time period, or prices come down on them a lot anyway by the time AC batteries are cost effective. The skeptic in me suspects 10 years before it becomes cost effective would be optimistic.
I hope to be in my current home in 10 years, but it's a lot time to try and predict, and longer than my panel payback period (was ~7-8 years, closer to 8-9 with the additional costs of having the roofer do the flashing, Enlighten Manager view, etc, not factoring in PG&E rate increases or severe negative impacts on returns).
Basically I could imagine springing for the Metered unit, and then having it die or become obsolete before I take advantage of it. i.e. a newer Envoy ends up becoming required, or how it's integrated changes and the Envoy installed becomes irrelevant. Still, $150 isn't a terrible premium to risk, needs more thought.. All the little costs do add up though.
S280 micros
RegGuheert said:
ltbighorn said:
S280 microinverters
I was also looking at the new S280 inverters (vs the M250s). At wholesale prices, they seem similarly priced or perhaps "only" $10-20/unit more, (though I don't know if my installer is getting better pricing on the M250s), with the benefits of greater efficiency, higher max input power, and some sort of smart-grid capabilities that seem like they primarily benefit the utilities.
Agreed this is primarily for the (future) benefit of the utilities. But putting that another way, power factor correction *might* have *real* value to them in the future. I don't know how much, but you never know. Still, since this is an unknown possible benefit, it is best to focus on YOUR requirements first.
Yeah, I definitely imagine there are benefits providing real value to the grid, but given these are just coming to market, the presence of lack of mine in the system isn't going to break the camel's back. I have trouble imagining PG&E effectively compensating me for the value it provides, though. It seems like it's challenging enough for them to compensate people for requested demand-response behaviors, let alone something subtle like power factor tweaks.
Long detail on my panel situation, can skip here for those not interested
RegGuheert said:
ltbighorn said:
The other thing to figure out is if I'll be able to squeeze a useful number of extra slots for circuits on a sub-panel, for potential future use. Not sure how the rules on sub-panel sizes/feeds work when you don't plan to connect anything to them soon (no change in demand load calculations), but I guess that's something to research.
If you'll tell us what brand and model of panel you have, someone might be able to give you some tips.
Westinghouse 125A end-fed panel with a 100A input feed/breaker. Underground feed from the street (only about 10 ft to street). I believe with the 120% backfeed rule, this means I could have up to a 50A backfeed (125*1.2 - 100 = 50), though I should only need 20A for 12-16 M250s. Because my panel is within 3-ft of the gas meter, upgrading it would not only require getting the utility feed upgraded, but also completely relocating the panel, probably a major project.
16 slots, but 4 are consumed by the 240V input-breaker and electric oven breakers. Another 2 are consumed by 240V hot-tub breaker (currently off, came with the house, haven't gotten around to trying it out). That leaves 10 slots for house-hold circuits, 3 of which already have tandem breakers installed. At least 2, maybe 3-4 additional could be switched to tandems, it's a bit tricky because phase needs to be maintained when shifting circuits around, as shared neutrals are used on many circuits. This is assuming I'm not forced into AFCI+GFCI combo requirements, as the availability of those in tandems for my breaker type is currently very limited (unavailable?)
The three existing tandems look to have been added when the kitchen was remodeled by the previous owner, with the various dedicated circuits being needed for things like disposal, microwave, fridge, etc.
We have enough circuits now that we're not really over-loaded on anything, though I had to do some juggling to get things I'd rather not share a circuit on separate ones. Primarily keeping motors (like the gas washer/dryer) off circuits with sensitive electronics, or moving the L1 EVSE to the essentially idle 20A garage door opener circuit (plenty of room for both). Getting an available 240V circuit if I ever wanted an L2 EVSE (in no hurry, but probably eventually) would currently be difficult. And my home file-server shares a circuit with a currently unused kitchen island outlet, etc.
If everything was staying as it was today I'd leave it as. However, there's unfinished space on the ground floor in most of the homes in the area (including mine), many of which have been finished to add some subset/combination of den/bed/bath. Good chance that's something I'll tackle 3-8 years down the line, and I'd definitely need more circuits for that job. More for sanity reasons (not having weird combinations of rooms sharing circuits) and probably code requirements, vs overloading issues. If new rooms were added, there'd probably be effective 0A increase in peak demand. If there were future residents (let's say my parents moved in someday), then it's probably still at most 25A increase, on what's probably currently 40A peak usage (in theory electric oven + multiple space heaters + EVSE -- has never has actually happened).
There are some small benefits to a sub-panel even I didn't need it for the slots -- I've heard that Enphase's microinverter powerline communications with the Envoy can interfere with other powerline networking sometimes (which I use), and being able to ferrite-choke isolate the micros+Envoy can solve this issue. There's additional cost to a sub-panel obviously, but I would be able to take advantage of the tax credit for the work.
If I can get a meaningful number of additional slots for future circuits, then that feels like a pretty strong incentive to go ahead with it.
My research on this point is just starting, but it seems like the size of the sub-feed to the sub-panel isn't restricted by the backfeed rules, as long the solar feed has its own appropriately sized breaker (e..g 20A). Thus in theory I could send a 80A 240V feed to the sub-panel and give myself room for 8x 120V 20A circuits (2 consumed by the solar feed), which would be very nice.
But based on my early readings around sub-panels, it sounds like inspectors generally limit sub-panel sizes based on the estimated total load at the main panel. I'm not sure how this would be handled since I don't plan to add any circuits or load in the near-term. Maybe the L2 EVSE circuit at most.
So I really don't know yet how this would be treated. Some questions that come to mind are: Would they give me grief for a sub-panel with a bunch of empty slots and an 80A feed? What if I wire it to handle 80A, but only have 40A feed breakers installed now? If I do 40A now, and try to increase later when doing the additions, will it be more difficult? Then they'll be more work being done, possibly new codes, and actual anticipated load -- seems more likely they'd try to make me replace the main panel then if the electrical had to be touched. vs if I add one room at a time over the years, with 1-2 additional circuits used each time, to an existing panel.
But frankly I don't know if at some point they might force a major overhaul down the road anyway, because I've pushed past some sort of threshold in their mind.
RegGuheert said:
Frankly, I'm impressed that you are able to digest and comprehend all the implications of these details BEFORE your purchase. Good on you! (Clearly you've gotten WAY beyond "Ooh! Shiny!" since you are posting in a thread about the failure rate of the inverters you are considering.
)
Hah, you flatter me.
I try to do the most I can before the big checks are written, then stop stressing about those choices once they're made. Hopefully I haven't hijacked this thread too terribly. This thread is what got me comfortable with going with Enphase M250 microinverters, based on the failure data and discussion of the benefits/cons. Definitely useful. Thanks again to all who have shared their knowledge and experience.