Illinois Solar Credit + Tesla Production Estimates

[NxPTsl]

I placed my order and got the design. I am a bit skeptical about design, it seems the south roof is not most utilized. There is one vent and fan on south side of the roof and CHimney which and throws shadow on the panels. With the current design, tesla estimates 8233kWh, which seems low compare to other designs I have got.

E.g. I got a design for 7.26kW LG panels with SolarEdge Inverter with Optimizer, it has the first-year production estimated at 9812kWh. Which I doubt, but it still a huge gap.



I have other quotes with similar to Tesla hardware, but more panels on the South, and no panel on the East. That has estimates of 8689kWh.

It seems Tesla estimates are too conservative. Also, I think the south roof can be utilized more effectively. Am I wrong in thinking that?

Tesla Design:

Regarding SREC:

Illinois provided the first 15 years of estimated production credit within 1st year of production.


Estimated SREC comparison

Tesla is giving SREC credit $8160, for the life of the system. Anyone has used SRECTrade to sell credits on their own? My impression is with Tesla estimates it's going to be low compare to other estimates.

 

[isjka]

I'm getting panels installed in 2 weeks here in IL. I've always wondered when I see non-Tesla panels in my area if the installers pocket those credits, if you know what I mean. I was told to look at PV Watts. When I look there and use the same parameters Tesla did, the output is way higher than their estimate. Tesla said they purposely lower the estimate. Not sure how to take any of that. Either way, we're limited by ComEd and our 12 months past usage due to net metering.

 

[Chris25]

I’m in IL and PTO 2 weeks ago. Tesla handled my SREC. As for production, I do think Tesla is under estimating. Their app is crap but my smart meter account is showing higher production than estimated.

 

[wjgjr]

I’m in IL and PTO 2 weeks ago. Tesla handled my SREC. As for production, I do think Tesla is under estimating. Their app is crap but my smart meter account is showing higher production than estimated.

With only a couple weeks of data, things could certainly change as far as your actual production, but it seems like almost everybody who plugs their information int PVWatts gets a number a good 10% or more higher than what Tesla estimates. My guess is that Tesla wants customers to see annual numbers at or above the estimates they provide in almost all cases so they don't have to deal with customer complaints/questions. Lowering the estimates leaves them flexibility both for those with bad weather for a given year as well as for minor technical issues.

 

[TheTalkingMule]

There's also less air pollution and particulate matter due to pandemic related energy cutbacks. My solar production is up nearly 5% YTD because of that and having a little less construction dust in the neighborhood. I wouldn't worry about Tesla underestimating production, that's the logical thing to do so customers don't freak out.

As for SRECs....I'm on SRECtrade and they just pop into my checking account as they're generated/sold. No touch process, but I'm not sure how much they take for fees. Generally, I recommend people hold on to their SRECs rather than monetize for upfront discount if you can afford it. You're probably giving away a huge chunk by taking it up front. If I'm not mistake, IL SRECs are absurdly generous.

 

[wjgjr]

There's also less air pollution and particulate matter due to pandemic related energy cutbacks. My solar production is up nearly 5% YTD because of that and having a little less construction dust in the neighborhood. I wouldn't worry about Tesla underestimating production, that's the logical thing to do so customers don't freak out.

As for SRECs....I'm on SRECtrade and they just pop into my checking account as they're generated/sold. No touch process, but I'm not sure how much they take for fees. Generally, I recommend people hold on to their SRECs rather than monetize for upfront discount if you can afford it. You're probably giving away a huge chunk by taking it up front. If I'm not mistake, IL SRECs are absurdly generous.

I do wonder how much different areas of the country did see noticeable changes in air quality with the pandemic. It does seem to have made a difference - though I don't think I've seen anything quantifying its impact on solar.

The issue for IL is they don't have SRECs in the same way as other states that trade on SRECTrade (which I also use.) Instead, they have an Adjustable Block Program (ABP) where you sell 15 years of credits in one block. The problem is that it seems to be very difficult to manage this sale on your own as you need to find an authorized company to handle it, and it seems like most or all of them only work with installers, not consumers. SRECTrade itself seems to indicate that is what they do in IL - work with solar companies to manage the ABP process, but not directly with consumers.

 

[isjka]

I’m in IL and PTO 2 weeks ago. Tesla handled my SREC. As for production, I do think Tesla is under estimating. Their app is crap but my smart meter account is showing higher production than estimated.

The smart meter account via ComEd? Can you share how your account shows higher production? Thanks.

Install is scheduled in about 2 weeks. How long did it take to get turned on after the inspection?

 

[Chris25]

The smart meter account via ComEd? Can you share how your account shows higher production? Thanks.

Install is scheduled in about 2 weeks. How long did it take to get turned on after the inspection?

No, I’m not ComEd. I’m in Naperville who also provides their own utilities. I can login to my smart meter and view usage and power generated.
When I look at Tesla’s app, it shows that I have not sent any electricity back to the grid. If I look at my smart meter, it shows that I am sending juice back to the grid around mid day. I tend to trust the smart meter data since that’s what I am being billed.
I also did a test over the weekend. Turned off all my breakers except solar for an hour. The app still showed that I was pulling from grid while solar was generating.
Naperville is also a little unique. You instantly get PTO after passing inspection. Tesla powered it on once the inspector said everything was good.

 

[BrettS]

I also did a test over the weekend. Turned off all my breakers except solar for an hour. The app still showed that I was pulling from grid while solar was generating.

So those graphs are really odd, but maybe kind of helpful to try to figure out what is going on and why the tesla app isn’t reporting correctly.

The tesla system doesn’t actually directly monitor how much power your house is using. It does directly monitor solar production and the amount of power you are using from or sending to the grid. Using those numbers it’s able to figure out how much power your house is using. So if your house usage data is off it’s because either the solar production data and/or the grid data is off.

However, there aren’t really very many reasons why the grid data could be off. The CT’s could have accidentally been put on the wrong circuit, or one of the CT’s could have been installed in the wrong orientation.

I don’t think it’s likely that the CT’s were installed on the wrong circuit because the grid usage data in your graphs looks like the usage of the whole house, rather than an individual circuit. Unless maybe you have a subpanel with a number of circuits on the subpanel and the CT’s were put on the subpanel.

However, if that graph is from the day that you did your test and turned off all of your circuits for an hour then no matter where the CT’s were installed you should have seen zero grid usage since all of your circuits were off. The same thing would apply to a CT installed in the wrong orientation. When you turned off all of your circuits the grid usage should have dropped to zero.

Honestly the only thing I can think of that seems to fit what you are seeing is that Tesla somehow has someone else’s power blaster attached to your account and you are seeing the grid usage data from a completely different house. I know you mentioned that you think your solar production data is off as well and that makes me wonder if the solar production data is coming from another house as well.

I’d love to see what would happen if you turn off your power blaster and your inverter completely. I’m beginning to suspect that you will still see grid usage and solar production appearing in your tesla app. If that’s the case then it seems like it would be easy to call tesla and say “Um... something is wrong... when I turn everything off completely I’m still seeing solar production and power usage in my tesla app”

 

[isjka]

Is there any way to check to see if the App is reporting correct data immediately after the install? Would rather not have the installers leave if the App doesn't work.

 

[BrettS]

Is there any way to check to see if the App is reporting correct data immediately after the install? Would rather not have the installers leave if the App doesn't work.

If you have a solar/powerwall install then the app is activated while the installers are there and it can be tested at that time.

Unfortunately with solar only the app isn’t activated until after PTO is received, so it is unable to be tested at install time.

 

[Chris25]

@BrettS
Here’s my smart meter data from the same day. Red is back to grid and blue is purchased.
I’m 100% confident that Tesla is wrong. Comparing 2 days at approx the temp but cloudy/sunny. The sunny day shows my house usage followed the same trend line as solar production. I’m to the point that I just laugh at the data. Can’t wait to see how Tesla handles the production guarantee! IMO, the system is not subtracting solar production from total flow to breaker. Not sure if this is an install issue or programming issue.

 

[BrettS]

@BrettS
Here’s my smart meter data from the same day. Red is back to grid and blue is purchased.
I’m 100% confident that Tesla is wrong.

Yeah, just looking at those graphs I can tell that the Tesla data is wrong, but I’m trying to figure out why it’s wrong.

Can’t wait to see how Tesla handles the production guarantee!

Did you purchase or lease your system? There is no production guarantee for purchased systems, but there might be for leased systems. I’m much less familiar with the leasing option as it’s not available in this area

IMO, the system is not subtracting solar production from total flow to breaker. Not sure if this is an install issue or programming issue.

The system doesn’t subtract solar production like that. The system measures your total solar production as well as the amount of power going to or coming from the grid, then adds them to figure out how much power your house is using.

So under normal circumstances you would have cases like this:

At night:
Solar: 0kW
Grid: 1.5kW
House: 1.5kW (0+1.5)

During the afternoon:
Solar: 5kW
Grid: -3kW (negative indicating that power is flowing back to the grid)
House: 2kW (5+(-3))

During the late evening:
Solar: .5kW
Grid: 1kW
House: 1.5kW (.5+1)

However in your case your power blaster is never showing any power going back to the grid and I can’t figure out why. In fact, it seems eerily consistent throughout the entire day, whether your system is producing solar power or not. Additionally you said that you shut off all of your breakers for an hour one day and, assuming the graph you posted above is from that day, there was no indication of zero power draw from the grid.

Based on that info the only thing I can come up with is that the grid data that you are seeing in your tesla app is coming from another house entirely. If I was mistaken in my assumption and you did see the grid usage number drop when you shut off all your breakers, then I guess I’ll need to come up with another theory.

 

[Chris25]

Thanks for the feedback. The saga continues...

if I turn off my solar, I can see it drop in solar production so I’m pretty sure it’s my data. I’m running an ethernet cable to the inverter in the near future to dig deeper. I’m not in too much of a rush since I can see my meter data showing it’s working correctly. I’ll keep you posted.

 

[BrettS]

Thanks for the feedback. The saga continues...

if I turn off my solar, I can see it drop in solar production so I’m pretty sure it’s my data. I’m running an ethernet cable to the inverter in the near future to dig deeper. I’m not in too much of a rush since I can see my meter data showing it’s working correctly. I’ll keep you posted.

OK, so if you turn off the inverter you can see a drop in production, so that would certainly indicate that the solar production shown in your app is yours and that’s good. But I still question whether the grid usage data is actually yours. Just to verify, when you shut off all your breakers the other day you did not see a drop in your grid usage, correct?

 

[NxPTsl]

There's also less air pollution and particulate matter due to pandemic related energy cutbacks. My solar production is up nearly 5% YTD because of that and having a little less construction dust in the neighborhood. I wouldn't worry about Tesla underestimating production, that's the logical thing to do so customers don't freak out.

As for SRECs....I'm on SRECtrade and they just pop into my checking account as they're generated/sold. No touch process, but I'm not sure how much they take for fees. Generally, I recommend people hold on to their SRECs rather than monetize for upfront discount if you can afford it. You're probably giving away a huge chunk by taking it up front. If I'm not mistake, IL SRECs are absurdly generous.

You installed panels through tesla and using srecTrade for SREC? If so do you see any benefit compare to selling to Tesla. Also what's the process to get SREC trading through srecTrade, I have read multiple places that srecTrade doesn't work with the customer in IL. Is that true?

 

[wjgjr]

You installed panels through tesla and using srecTrade for SREC? If so do you see any benefit compare to selling to Tesla. Also what's the process to get SREC trading through srecTrade, I have read multiple places that srecTrade doesn't work with the customer in IL. Is that true?

That appears to be correct that SRECTrade does not work directly with consumers in IL (though they are an aggregator for the ABP program in IL, it seems like they work only with installers.) In markets where SRECs can be sold, it seems there is a significant financial benefit to retaining the SRECs and selling them through SRECTrade (or another company) versus selling them to Tesla, as is the case for us in MD. But, again, it seems like IL doesn't currently have good (or any) options other than accepting the amount from the installer (and others indicated Tesla offers in IL are on par with other installers.)

The process for registering through SRECTrade does vary a bit by state since each has somewhat different rules, but, in general, my understanding is you fill out a few forms, some of which need to be sent to the state to approve your site as eligible for the SREC program (and SRECTrade sends the forms in for you, except where you have to yourself by state law.) Once that is done you are essentially up and running. On a monthly basis, your production will be added to your account - either automatically if they can access the data directly somehow or estimates can be used (which applies to our array due the rules in MD for small arrays) or manually by you entering the monthly production data. Every 1 MWh generated = 1 SREC, which you can then sell. SRECTrade has a few options, from them selling them automatically (and depositing proceeds in a bank account) to you having full control over when to sell.

 

[Bobbhisar]

I’m in IL and PTO 2 weeks ago. Tesla handled my SREC. As for production, I do think Tesla is under estimating. Their app is crap but my smart meter account is showing higher production than estimated.

Hi Chris, I am planning on getting Tesla solar panels and I am in Illinois. Have you had good experience with Tesla solar? Will appreciate if you can share. Thanks