Worth switching to net "time-of-use" metering for grid-tie solar system in NY (ConEd)

[snic]

Ok, I spoke with someone at ConEd here in NYC who (finally) seemed quite knowledgable about the time-of-use and net-meters, Jim from the Distributed Generation Group. He explained why TOU billing does not work out well for 99% of customers with solar panels. Why this information is not available on their website is another question, but he did mention they're in the process of doing a "large data project" on the topic, so hopefully that will result in improved information throughout the company. In any case here's the story...

As you probably know, ConEd's TOU billing splits the day into segments; Peak which is weekdays from 10am-10pm and Off-Peak which is weekends and 10pm-10am weekdays. The two segments are billed at different rates and, most importantly for us, the power generated in one segment is apparently NOT applied to the other segment. What that means is that all the power generated during weekdays is applied against your weekday usage, but not against your nighttime/weekend usage. So you likely end up with a surplus of Peak power and a deficit of Off-Peak power. That part makes sense, but where ConEd gets you is that they don't pay you for your surplus of Peak power at the Peak power rates. Instead they wait until the end of the year and then pay you for any surplus at that point based on what sounds like the lowest rate of the year. So in other words you pay high rates for any net-deficit you have, but you get paid low rates for any net-surplus you end up with.

So in my case, despite Jim's suggestion that I skip the TOU meter, I've gone ahead and requested the TOU+Net Meter, since the TOU billing is voluntary and I can cancel it at anytime (http://www.coned.com/customercentral...svoluntary.asp). While I believe him that the TOU billing will likely not benefit me given the current billing policy, having the TOU meter will allow me to measure my peak vs off-peak usage and will put me in a better position to choose TOU billing or not.

Hopefully this all makes sense, but let me know if you've got questions about it. Also let me know how things have sorked out in your situation. Thanks!

Thanks for this summary - it's very useful. I share your frustration that this information isn't posted anywhere on the Con-Ed website.

The part I bolded is intriguing. What this suggests to me is that Con-Ed is willing to pay retail rates for surplus energy generation if you have a TOU plan. Are you sure that's what will actually happen? If you don't have TOU and you generate a surplus in a year, they will buy it from you at wholesale rates ($0.05/kWh or something like that).

If Con-Ed really pays retail for surplus generated at peak times (even if it's the lowest retail rate of the year), that might change the equation considerably. If you can generate sizeable surpluses, then selling that power to Con-Ed at retail might go some distance towards the cost of power you use at night and on weekends.

I'm glad you're getting the TOU meter and trying the experiment - please be sure to report the results!

[MrBoylan]

Still murky

Hey CB, any updates?

I recently got a PV installation on my house here in NYC (although mine is larger at 7.194kW) and I'm currently debating whether TOU would be worth it. The ConEd folks I spoke to so far have advised that it's often not worth it, but I'm wondering what your experience has been so far?

Thanks!
Ben-

So I finally sat down to do some analysis of our bills since going TOU and... I still have no idea whether it was worth it. I think this TOU thing is still new for ConEd because our bills do show two different meter readings but there is *NO* indication anywhere on the bill of the peak vs. non-peak rates and charges. For example, for November of 2013, our "meter 1" usage was 182 kWh and our "meter 2" usage was 433 kWh. I'm assuming the higher number is off-peak because the solar is offsetting peak usage and we're scheduling higher power tasks for nights/weekends, but I'm not 100% sure of that. In the charges part of the bill it just takes the total usage (615 kWh) and multiplies that by the delivery charge ($.1074/kWh) and the supply charge ($.1433/kWh). So that's a net cost per kWh of about 25 cents (plus tax) per killowatt hour of usage for November.

Online the situation is even worse as it only shows net usage with no distinction between peak and off-peak usage. But we did get a mystery credit of almost $800 on our bill in December of last year, so maybe that's some calculation of TOU rates and credits?

I've got another e-mail into ConEd about it to see what's going on but I may end up having to call them and (hopefully) will get to speak to someone who knows what they are talking about. Either they forgot to switch me over to the new TOU billing or they're doing the math behind the scenes and not showing it on the bill nor online.

The only thing clear to me is that ConEd's bills and online information system are pretty weak. Will update the thread if I learn more.

Thanks,

-Chris

[DanS26]

So I finally sat down to do some analysis of our bills since going TOU and... I still have no idea whether it was worth it. I think this TOU thing is still new for ConEd because our bills do show two different meter readings but there is *NO* indication anywhere on the bill of the peak vs. non-peak rates and charges. For example, for November of 2013, our "meter 1" usage was 182 kWh and our "meter 2" usage was 433 kWh. I'm assuming the higher number is off-peak because the solar is offsetting peak usage and we're scheduling higher power tasks for nights/weekends, but I'm not 100% sure of that. In the charges part of the bill it just takes the total usage (615 kWh) and multiplies that by the delivery charge ($.1074/kWh) and the supply charge ($.1433/kWh). So that's a net cost per kWh of about 25 cents (plus tax) per killowatt hour of usage for November.

Online the situation is even worse as it only shows net usage with no distinction between peak and off-peak usage. But we did get a mystery credit of almost $800 on our bill in December of last year, so maybe that's some calculation of TOU rates and credits?

I've got another e-mail into ConEd about it to see what's going on but I may end up having to call them and (hopefully) will get to speak to someone who knows what they are talking about. Either they forgot to switch me over to the new TOU billing or they're doing the math behind the scenes and not showing it on the bill nor online.

The only thing clear to me is that ConEd's bills and online information system are pretty weak. Will update the thread if I learn more.

Thanks,

-Chris

Chris....You seem like a detailed oriented person that really wants to know their utility usage usage and rate paid. Stop screwing around trying to interpret the utility bill. Get a TED system (or equivalent) system installed on your main electrical distribution system. Then you can monitor your electrical usage minute to minute...hour to hour...day to day...month to month...year to year. No more guess work about the utility bill.

It's not that difficult

[Volusiano]

Chris....You seem like a detailed oriented person that really wants to know their utility usage usage and rate paid. Stop screwing around trying to interpret the utility bill. Get a TED system (or equivalent) system installed on your main electrical distribution system. Then you can monitor your electrical usage minute to minute...hour to hour...day to day...month to month...year to year. No more guess work about the utility bill.

It's not that difficult

Maybe the problem is not just about not knowing what the production and usage data is. Sure, with the data, it may help decipher the bill more easily. But maybe not, if the TOU model and the way the POCO calculates everything is too complicated and confusing, actual independent usage data of your own may not help. You should still understand how they calculate the bill thoroughly to make sure that there's no error in their calculation, and more importantly, whether the net savings is realized or not after all the TOU calculation is done.

Once you figure out exactly how the billing is calculated, you can then model it on a spreadsheet or something and plug in either real production/consumption data or estimated data to help decide whether TOU is for you or not.

[DanS26]

Maybe the problem is not just about not knowing what the production and usage data is. Sure, with the data, it may help decipher the bill more easily. But maybe not, if the TOU model and the way the POCO calculates everything is too complicated and confusing, actual independent usage data of your own may not help. You should still understand how they calculate the bill thoroughly to make sure that there's no error in their calculation, and more importantly, whether the net savings is realized or not after all the TOU calculation is done.

Once you figure out exactly how the billing is calculated, you can then model it on a spreadsheet or something and plug in either real production/consumption data or estimated data to help decide whether TOU is for you or not.

The TED is pretty sophisticated in calculating TOU billing. Not all but most utility TOU billing schemes can be replicated.

I make the TOU comparison with regular rate schedules monthly with the TED. It's not "revenue grade" measurement but close enough for you to make the comparisons.

[MrBoylan]

Chris....You seem like a detailed oriented person that really wants to know their utility usage usage and rate paid. Stop screwing around trying to interpret the utility bill. Get a TED system (or equivalent) system installed on your main electrical distribution system. Then you can monitor your electrical usage minute to minute...hour to hour...day to day...month to month...year to year. No more guess work about the utility bill.

It's not that difficult

Thanks for the reply. The TED system does look interesting, but in NYC homeowners are not allowed to do their own electrical work so I'd have to hire a licensed electrician just to hook this up to the box and I'm not sure it's worth the expense. If I upgrade my service from 100 to 200 amps (which I'm planning to do next year) then I'll probably put a TED unit on the box when I do that.

The fact is the utility bill should at *least* show me the rates on-peak and off-peak, but it doesn't. I suspect they simply forgot to switch me over to TOU even after installing the meter last August.

BTW, I'm already putting the usage data into a spreadsheet (and adding the Sungevity solar power generation data) just to see how much I'm saving with solar each month. It's only about $50/month but I'll take it!

Thanks,

-Chris

[ajpslp]

I saved around $185 my first full month so far. I spoke to my sales rep who i became super friendly with about TOU meter. I actually have a 12.06 KWH Sunpower system and have consumption meter on system as well to see when i use my energy and how much , just in case i want to switch later on. He totally reassured me that it most likely won't work for us, unless u work nights and nobody home most of day. BTW con ed screws up first bill and sent me an estimated bill even though the con ed rep read my meter, cause i was in garage when he read it , why can't they just get it right !!! Thrilled with over production so far and my solar project is great !

[MrBoylan]

I saved around $185 my first full month so far.

That's great and will only get better in the Summer. In NYC last year, April through July were our best months for production -- output was almost double what we had in February.

This year has been pretty poor so far, partially because a storm in early February covered the panels with snow/ice that just wouldn't melt on its own. After 4 days of no production, I went out onto the roof to manually clear the panels off. It's a flat roof so not too bad but still no fun climbing up the ladder in the winter.

-CB

[MrBoylan]

So I finally sat down to do some analysis of our bills since going TOU and... I still have no idea whether it was worth it.

So for anyone still following the thread. We got our first ConEd bill with TOU rates in it, and I'm pretty sure they swapped out the peak and non-peak meters so we got billed peak rate for off-peak use and off-peak rate for peak usage. This was a net bill for all of our electricity usage from August until March (6 months) and this is what we we charged:

On peak - 2,933 kWh @17.7777¢/ kWh - $521.42
Off peak - 1,124 kWh @2.6886¢/ kWh - $30.22

This is for delivery charges only. The supply charge is apparently still fixed, even though we are on the TOU plan (not sure if that is another mistake or if that part is correct). Supply charges are another 14.32 cents/kWh (did I mention how expensive electricity is in New York City?).

But these peak/off-peak numbers don't make sense as our panels should be offsetting a fair amount of the peak usage and we've scheduled most power-hungry devices/tasks to off-peak hours and weekends. So now, I'll be recording the meter readings myself a couple of times a day for the next few days to verify which meter is which, then working with ConEd to try to fix things.

Why can't this stuff be easy?

-CB

[inetdog]

One nice thing about the digital smart meters out here in CA is that all of the TOU and tier information is based on readings from one meter.
That makes it much harder to screw up just one customer. Any problems with the algorithm would affect all customers and someone would holler sooner.

[MrBoylan]

One nice thing about the digital smart meters out here in CA is that all of the TOU and tier information is based on readings from one meter.
That makes it much harder to screw up just one customer. Any problems with the algorithm would affect all customers and someone would holler sooner.

Yes, I guess that makes things simpler. I'm not even sure ConEd uses computers.

I did send in the readings though, and our account rep said she would reverse the charges and start billing us correctly. I double-checked this morning and the higher number meter increased overnight which means that the higher number is definitely the off-peak usage number.

For anyone else using ConEd for voluntary TOU (Time of Use) with the GE kV2c net time of use meter, there is an "A" on the screen on the left during peak power usage times and a "B" on screen during off-peak. Also, the reading for peak usage on these meters is identified with an "8" and off-peak identified with a "9."

Hopefully this will help some others looking for information on this.

-CB

[fatshark]

switching back from TOU to flat

After looking at the data for over a year, it looks like TOU with ConEd is not worth it. I'm switching back to flat rate.

I live in Westchester, about 20 miles north of NYC, with 7 kW on the roof. We average 13 kWh per day of consumption. On an annual basis, we generate a little more than we use. We're on the grid with ConEd.

There are two issues with TOU that motivate me:

1. the Basic service charge is about 20% higher than flat rate and adds roughly $100/yr to the bill, and

2. ConEd buys back excess A-rate annually at what amounts to a wholesale rate which is very close to zero.

Every year, ConEd clears the books, buying back any excess. From what the accounting shows me, I'm paying for B-rate (off peak) when the panels don't generate, getting bupkis for excess A-rate (peak), and paying extra to have TOU service. I expect that when I switch back to flat rate, I'll have a lower Basic service charge and I'll be able to use excess day-time generation at night instead of getting paid almost nothing for for the excess generation.

Mind you, if we were net negative on A-rate instead of net positive, the math might suggest a different outcome. I think the issue here is that our system is big enough to make us net zero, but because excess A-rate is basically thrown away, we're not able to achieve that.

[fatshark]

super peak

I just ran the numbers for ConEd's new super peak TOU. Even worse for us.

[J.P.M.]

Back to one of the prior comments about T.O.U.: T.O.U. tariffs are different for each POCO, and will continue to change for each POCO going into the future. What holds true for a POCP in CA, will be different than for Con Ed in NY, and both will be different nearly every year as will all the tariffs as they respond to market conditions.

[JFinch57]

Your best bet is probably to shop for the cheapest supplier rate. In MD I locked into a 2 year contract with ConEd for 7.49 cents/KWh and there is no cancellation cost. Ran all of the numbers for TOU and it didn't make sense. During the day I'd be paying almost double and the house is not unoccupied. My contract is up in May and now they're in the low 8 cent range for 1 year, higher for 2 year. Will see what happens in May. Good luck!