Reconciling APS bill to Enphase

brlr2000

Does anyone have experience with reconciling APS monthly utility bills with the Enphase Enlighten data?  I have a simple Grid-Tie System without batteries.

BB.

Welcome top the forum brlr,

What is your APS rate plan like? My utility (PG&E in northern California) has been all over the map in the last 15 years. Used to be Time of Use billing (6 pm to noon, was one rate, noon to 6 pm was another rate on weekdays). Then it became more complex (up to 4 different TOU time "zones", weekdays were different than weekends, etc.).

Now, I can choose TOU or flat rate. The TOU became "less interesting" because the highest rates were late afternoon to 9-10 pm at night--Obviously, solar GT solar system is not generating any power once the sun sets (plus I have some western trees blocking evening sun).

PG&E now offers a evaluation of you bill based on your 1 year history ("smart" meters report back every 15 or 30 minutes back to the company) so they can accurately lay my usage over the various rate plans. In my case, Flat Rate was about exactly the same monthly till as one of the TOU plans. I choose Flat Rate as it is simpler and does not penalize me for cooking/running the wash in the evening.

See if your utility offers a website to compare your usage against multiple rate plans... Also see if your utility gives you daily graphs of energy usage (are you using more power during peak TOU, or less...). Figure out an approximate "average rate" for power usage (i.e., $0.20 off peak, $0.50 peak, for example use $0.35 for "average effective rate) and then multiply that times the Enphase daily/monthly reports.

You are sort of in a pickle. Most utilities use a single billing meter--So your Home Loads + Solar Power generation are mixed together. And if you have TOU... Then you need to track both loads and generation kWatts hour by hour. 

You can use PVWatts website to calculate your average kWH per month harvest for Phoenix AZ. Based on array size, roof angle and is the array facing south or another direction.... This way you can figure out if your system is performing to expectations or not.

-Bill

solar_dave

Yeah I have APS and had solar contract with them for over a decade.  I have a TED monitoring system and a separate meter for the solar along with the digital meter from APS.  I have never bee able to really reconcile ever kWh from my 3 sources.  Gave it up long ago, but happily my energy costs are very low for the APS region.  Last year it was under $500 for the whole year. This year I suspect it will be more as the solar system is getting a bit aged and output continues to decline. Still June billing was only $65.50 and of that $13.49 was generation (off peak).  I still got credited for 55 kWh on peak (sent them more than I demanded in total) which was a bit of a shock with the June temps.  I still have 1671 kWh in my APS bank but the service delivery charge has started to kick back in which means overall I have now received more kWh that I have sent in total.  I should make it till Sept before the bank is depleted.  I expect the meter to be really humming the next couple weeks as the temps will be over 110F everyday.  When you think about it that is a 30-35 degree delta and that is what a fridge does in a few cu. ft vs 2500 sq ft X 10 foot ceilings (25,000 cu ft).

Been considering a major conservation upgrade to the house with triple pane low e windows from Pella using fiberglass framing.  The 25 year old builder aluminum frame windows are slowly falling apart.  I am hoping that will reduce the AC usage considerably. Maybe even blow som additional insulation in the attic.

I figure in a few more years a new solar system will be needed but I have this grandfathered TOU plan and if I do anything major that will go out the window.  I talked to a couple installers about just a solar panel replacement as maintenance but the city want permits for major roof work.   That would trigger an APS review as well.