Starting to get the data to where I might believe it. I'm surprised with my findings. I finally had to bring in the standard RATE-D calculations to see them in comparison. I still need to update my calcs (certainly check/validate) for the other TOU schedules, I'm really only looking at TOU-D-A because it looked like it was the better one for me.
So, here's the surprising results (TBR)...
After installing 6kW system to try to offset ~100% of yearly kWh usage (which was just under 10kWh last year), I've found my neighbors trees are shading my system at sun up and sun down more than I expected, so I'm NOT on track to meet my goal. Current estimates show that I will still pay SCE $273.18 per year with my 6kWh system. Yuck.
The good news now. TOU-D-A shows I'll have a credit of $283.13 for the same period if I've done my math correct. I am using my last year's usage for forcasting the future with no adjustment. For solar predictions, I'm more uncertain since I'm not getting anywhere near PVWatt's outputs for my system. I think the worst is behind me, where my neighbors shading affects me the most during Winter solstice (low sun angle). For my current predictions, I used a 10kWh PVWatt hourly output run and then I applied an 85% factor to each hour. This says my 6kW system will product ~8.5kWh/year. I've had some good outputs lately, I just don't have any confidence because for Nov, Dec, and Jan my generation was close to HALF of what PVWatts predicted. I think Feb was much better at 104%, but I'm just not sure. Anyway here's the graph:
I show 4 curves for TOU ( RED = Usage, BLUE = Production, PURPLE = Credit, GREEN = Net $) and one for standard Rate-D (Tiered, Light BLUE)
tou_analysis_2015.02.28.JPG
Take a look at the graph and see if it passes your smell test. The "credit", purple line, is because on TOU-D-A they give me ~.10/kWh upto 130% of baseline. I also haven't gotten very accurate baseline #'s yet, they'll skew things a bit too. The xlsm file has gotten a bit out of control as I iterate different things (10MB now).
Thoughts?
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So, I haven't had a lot of time to play with the spreadsheet. I have tried to look at things per JPM's suggestion of (+) and (-) separately. Sometimes that helps, other times it is confusing. For example, with my TOU-A credit, it only applies to energy consumed and only upto baseline. So as long as my cumulative monthly consumption is below baseline, I get a $0.10 credit for each kWh CONSUMED that hour. My production effectively reverses that credit. Fun stuff. Anyway here is a graph of how my January & Feb gen/consumption would have broken down in TOU-A for SCE:
JAN
tou-ex_graph.JPG
FEB
tou-ex_graph2.JPG
Once I figure out how I want to slice/dice the data and fix it to work on all 3 TOU options, I'll share the xls. Now that I have the data, figuring out how to look at it has been very challenging! For example, if you look at the second graph (Feb), and look at the credit column, you'll see both positive and negative credit. I produced more green "off-peak" than I used, so I net "undid" $15.76 work of credit, but in the other two categories, I used more than gen and was able to produce $35.66 credit....net credit of $19.90. Similar to comparing gen/consumption....if I were to graph a single stack of net gen/consumption, I'd have some periods (off-peak) of negative and other (super off-peak and on-peak) of positive, so the net gen/consumption wouldn't just be in a single direction, but some above the line and others below. It's honestly weird and I'm really struggling figuring out what I *want* to see right now. Also, I am not including the fixed $ in these graphs, haven't decided how I want to show that either.Leave a comment:
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The 20 yr. grandfathering is written into current legislation, so it is approved at this time. As you write, things will change. I'm quite sure the big 3 CA IOU POCO'S never wanted it in the first place and will do what they can to minimize its impact on profits. To the extent capitalism is a reality, evil or not, it's still just business and you can count on it.
One way to minimize the individual impact of anything the POCO's do starts something the POCO's cannot control: individual users internalizing the concept that the less electricity is used, the less impact POCO rate shenanigans can have on your situation. Use less. You'll save money, and the POCO's won't get in your knickers quite so far. Added free bennie for tree huggers: you'll leave a smaller amount of spoor in your wake that does bad stuff to the environment. Walk the walk.Leave a comment:
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I'm also in SDG&E's area, but I think most of the CA POCOs will be following similar strategies.
The 20 years sounds great, but SDG&E will surely change some things to reduce any benefit you get from it. Obviously rates change, but SDG&E also has a plan to shift the "peak" hours to later in the day, 2pm to 9pm. This means much of your generation will be shifted to semi-peak and much of your consumption to peak. As of now, it's not clear what parts of net metering will be grandfathered, but I would bet the time shift will apply to all TOU customers, just like the new rates.
Also, it appears SDG&E wants to make TOU mandatory for all customers by 2018. With TOU hours changing, rates changing, monthly fees, and all customers shifting to TOU, the ROI on solar will likely be significantly lower.
Of course, none of the above is approved yet, but it seems the customer rarely comes out ahead with the CPUC.Leave a comment:
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someone told me the same before, but just thought it was too good to be true since during the summer time during the bulk of the solar generation SDGE would be "buying" electricity at almost 50 cents per kwh while EV owners would "buy" electricity at just 1/3 of that cost during max off peak hours.Leave a comment:
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Yes, the "net metering" agreement that is protected for 20 years from your system start-up means that the credit you receive for energy generated is the same as what you would have paid for that energy if you bought it. Specific rates, tiers, or hours of TOU may change, but the basic agreement that you get full retail value of your generation will not.Leave a comment:
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TOU with EV and Solar
My appologies if this question was already asked and answered but I can't seem to find it anywhere.
Does the solar output match TOU tiered pricing?
For example, I'm in SDGE territory and during the summer from noon to 6 PM the cost per kwh is 0.49/kwh, does that mean power generated during that time is counted at 0.49 per kwh too?
I'm currently on the EV-TOU-2 pricing plan under SDGE. To me, it would only make sense to stay under the TOU pricing structure if the above is the case.Leave a comment:
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FWIW, I started with the smallest increments available, 1 kWh and 1 hr. increments. ( then 15 min. increments came along). That allows the most flexibility but requires the biggest spreadsheets. Stick with the hourly PVWatts and remember, PVWatts is an estimator NOT a predictor. Better yet, use SAM.
Meant as a respectful suggestion, I started with tiered rates and got familiar with all the nuances and devils the POCO hides in plain site. I found it best to start at the beginning with my bill, the tariff sheets, figuring a bill and then getting a calculation to match what my actual bill shows. Then, I did the same for prior bills.
There are sites that get close to my tiered stuff, but leave out the billing period adjustment. I'd be wary of paying some spreadsheet guru to do this stuff. No offense, but after doing it for a while, you'll know enough to shake your head at the foolishness and amateurishness of some things called accurate. Some stuff is decent. Most of it leaves some stuff out. Truth to tell, mine probably does too, but I fix 'em as I find'em and I'm finding far fewer as I go. Biggest PITA now is keeping the rates current.Leave a comment:
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I'm interested
Both SDG&E and SCE allow you to download your usage using "Green Button" it will download your usage for up to 13 months? or a specified recent time period in 15 minute intervals. You can get this as an excel file, CSC file, and others I believe. There is work being done on a platform to convert this data into intelligible information. There are some commercially available programs that can utilize this data. Others are working on a consumer facing option using "Green Button Connect" software. I've been considering hiring a software developer to program something that would automatically gobble up the data and spit out something of a best case worst case scenario of your current usage. Hopefully be able to add solar scenarios to determine the best outcomes. Wasn't sure anybody would be interested. Sounds like at least 5 of us would be interested.Leave a comment:
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What I think I may do, is to see if I can download past hourly consumption data from SCE. Then try to get a pvwatts estimate that I'm happy with (I don't have this yet because I've got some shading that is worst in Winter, so I'm not sure if it's mostly gone by Summer solstice? It makes for predicting my output tough) and fill that into my spreadsheet. I'll somehow make a column to note source (measured vs estimated) and upload the spreadsheet here for anyone that wants to take a look. Currently, I don't have the standard tiered calculations in the spreadsheet, they are in another ROI spreadsheet that I'm monitoring, so although I have the "actual bill" showing, that is simply input not calculated based off my current tiered plan.
I appreciate the conversation and the interest/willingness to check each others work! JPM, I need to look for this more detailed POCO/PCUC sheet for SCE...
More to come. I kind of think that I might have an error currently since my spreadsheet shows that my last bill I paid $30.29 (would have been $170.83 w/o solar) would only cost me $6.45 on TOU-D-A and I only produced 584kWh for those 32 days. Again, I'm expecting my production to increase up to another 50% or so by peak season (rough estimate), so I guess I was thinking TOU would punish me more during Nov-Feb...Leave a comment:
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I have tried to calculate and estimate my annual consumption, but more I do it the more I know I'm off. My consumption were all different from past 3 years. So I take a easier route by add few more panels. I'm in TOU-D-A plan now and I'm glad SCE has made my life easier with showing all 3 (peak, off peak and super off peak) totals.
I have TED5000 and not everyone has it.
First, I think you should understand your solar arrays and determine when is your main output hours. Luckily I have my solar running more than 1 year and my solar arrays were facing SWW 245 deg which TOU make sense to me. Since I already have all the datas (SCE and TED5000), I know what I needed is covering my Winter heating consumption. (everyone were different on this)
So I pick Jan 10th, 2015 which I used about 48kWh from SCE and my solar produced about 9kWh. (see the picture. the info is free on SCE.com)
Base on the graph, my main consumption fall under super off peak from 10 to 8am (11 cents) I would prefer to use high credit to cover the lower rate during super off peak.
Summer usage can be tricky.... Look at the 3rd graph. My solar produced 36kWh but still withdraw 64kWh from SCE.... When both ACs are on, thing can be real ugly. I think I can only bank during Spring......Leave a comment:
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I'm mostly up to my best intentions in SDG & E rates at this time.
Part of my suggestion was that the POCO CPUC tariff sheets are easier for me to use once I learned how much necessary detail was buried (hard to pull out) in the POCO blurbs that are put out for general information. I'm on board with the lament of POCO's making it hard to decipher just what's going on. Using the tariff sheets gets you more info, but that info seems a bit easier for me to comprehend. Not a shortcut, but better.
Over the years with this rate business, I've found what I early on considered extra bells and whistles are almost always necessary pieces of information. Example: Getting the proper billing schedule. Such things are fairly straightforward to put together. If a computer Luddite such as me can do it and get it right, I'm sure anything anyone else who has an eyeball and a balloon knot can do at least as good, and easily superior. I just piggybacked on the tariff sheet information and logic, converted to rows and columns.
I double check the tiered calcs in two ways: Every time there is a change in any of the factors that are part of the overall rate(s), usually quarterly or more often, and when I compare neighbors' actual bills against what I calculate as an estimate. Of all the folks in my HOA I don't know of any on T.O.U. at this time. That seems in line with something I read and wrote about from some testimony from an SDG & E exec. that said something like some fraction of 1% SDG & E's residential rate payers were on T.O.U. My memory might be off on that one. As I wrote, my T.O.U. stuff is ongoing - the rates are fairly easy, the usage is the devil part.
Sort of an aside on the POCO's making it hard to figure out what to do: I wonder if they (the POCO's ) have considered that if they made it super easy to ACCURATELY calculate a bill for usage in various ways that it might just work to their benefit in the sense that it will be easier for customers to see just how cost ineffective it can be to offset an entire electric bill vs., say a 70-80% offset. And so, maybe, be able to see that to offset the last ,say, $400-$500/yr. in electric bill will take the system cost up by, maybe say $5,500 x .7 = $3,800, moving their system breakeven time out a couple or 3 years. If so, maybe folks would buy more appropriately sized systems (smaller ?), or at least have access to more information on which to base their decisions.Leave a comment:
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