Update: I spoke with someone with the city last Friday and got some more details to shed some light or further confuse things. lol
For starers, our city rates are:
Winter $0.085/kWh
Summer $0.10/kWh
The good news is our rates are low so our bills are also low. The bad news is this makes it more difficult to recoup initial investment costs of our solar system. She also informed me that rates would increase 4.7% next year and likely even more the following year as we start to move to a higher renewable production model. Around 5% increase each year would certainly help to recoup solar investment costs quicker but that's difficult to predict for so I'd like this to all make sense w/o even factoring this in since it's unpredictable at this point since there's no guarantee of a ~5% increase each year. Heck, if our city gets onboard with solar/power packs we may even see an eventual decrease in costs.
Early in the conversation her opinion was that my estimate of production seemed low for the # of panels. She suggested I have Tesla "show me a PV watts output" before I make a decision. Does anyone have any thoughts here as to whether this is around what we should expect or not? I'll post a photo of the proposed layout so you can get an idea. We have no shade currently nor will we likely have any in the future either.
We also currently pay about $15/mo access fee which goes up to about $42/mo for our size array. She explained that a small portion of the monthly access fee was also built into the kWh rates historically so they increased this access fee for those who were going to solar since they wouldn't be recouping this fee spread out over usage. Makes sense. She said that they still run an ancient billing software that is DOS based (yikes!) and that they anticipated an update by the middle of next year. She said lots of changes and updates were coming once that is completed. As of now though there's no provisions for ToU.
They would install a bi-directional meter which measures how much you use and how much you send back. Retail value 1:1 is paid for what you send back. So 100% of what you produce is returned in terms of a credit. No wholesale buy-back the way I've seen others report. That seems like good news to me. She mentioned that within the next couple of years that 100% buyback would likely change to roughly a 2-cent per kWh difference decrease. That's still far less than what I've heard others report their wholesale buyback figure is so I'm still alright with that.
She did say though that it makes more sense if you can use the power you produce at the time of production rather than selling it back to them during the day and using at night. That part didn't make as much sense to me since 1:1 should mean that it would be a wash but she said it had something to do with the way the meter read and how their ancient system accounted for it. This part didn't make much sense to me. If anyone has a better understanding on this I'd appreciate a different approach to the summation of what that is. To me it seems like the choice to not add a Powerwall now is still the best move. She said that they would likely have ToU in the next few years at which point I'll revisit that decision.
If I'm using 1,800kWh/mo on average (taken from previous utility statements) and my production is roughly 1,100kWh/mo I'm putting my "savings" at somewhere around $75/mo which is a far cry from what I was originally estimating based on arbitrary figures since I didn't have real numbers. At that rate we're talking more in the realm of 20 years of so to pay off our initial investment or nearly double what I was estimating. The only difference is if our array produces more than estimated and does so consistently and if that ~5%/yr increase is also consistent. Those two things may lower that recovery period to about 15 years or so but that's still a long time.
I'm just not sure that this is the best solution for me unless there's something I'm missing here. Anyone care to add their input based on the above? Any insight that can be offered would be greatly appreciated.
Are you sure the winter/summer rates that you were given represent the total cost per kWh? Normally there is also a Delivery charge as well as other charges which are on top of the actual charge for the energy. These additional fees would increase the kWh rate by several cents and represent the true cost you are paying. I would estimate they are probably an additional $0.03/kWh. If you look at a current bill, you should be able to see the additional charges and true cost per kWh.
You can use PV Watts to estimate your production here: PVWatts Calculator. When I checked our proposed system with PV Watts, I calculated numbers that were very close to what Tesla's numbers were, like within 300 Watts. Fortunately, we actually already beat the estimated yearly production nearly a month early. Based on your 1800 kWh average, it still looks like your system would offset about 63% of your annual usage. Is that about what Tesla estimated your offset would be?
I'm surprised that Xcel is so different for your town vs. ours. I don't believe our "access fee" changed at all when we installed solar and we do have ToU available where we live. ToU, especially when combined with Powerwalls, helps to greatly reduce your bills and helps solar pay for itself a lot faster. If you can't get ToU then you won't be able to always use off-peak and shoulder rates like we do. That does reduce the benefit of having Powerwalls somewhat. You'll still be able to bank your credits for over-production in the summer (if you have any) but wouldn't be able to power your house or use your solar if the grid was down.
When we first signed up, we were confused by Xcel's documentation as well. It's like they try to confuse you and convince you not to get solar. Imagine that.