Understanding tiered TOU rates with PG&E solar

[J.P.M.]

Unfortunately, that's exactly what National Grid in Upstate NY does. During off-peak times of the day/year, solar power generation is credited at the off-peak rate, as you would expect. But during peak times of the day, National Grid predetermines how much solar generation will be credited toward peak/shoulder peak/off-peak rates. Surprise surprise! Whodathunk the POCO would stack the deck in their favor

It's just business. I'd not want to run an enterprise where I had to pay the same price I sold my product for. While not a big fan of POCOs, I try to remember they are in business to make money. Their behavior is not a surprise to me. It's Capitalism.

[truav8r]

I'd not be surprised at efforts to delink what a generator on T.O.U. pays for power from what that generator gets as revenue from the POCO for power generated during similar time periods. Watch for it.

Unfortunately, that's exactly what National Grid in Upstate NY does. During off-peak times of the day/year, solar power generation is credited at the off-peak rate, as you would expect. But during peak times of the day, National Grid predetermines how much solar generation will be credited toward peak/shoulder peak/off-peak rates. Surprise surprise! Whodathunk the POCO would stack the deck in their favor

[J.P.M.]

I will add this: Echoing what another poster said above, PG&E makes it so confusing that it would be nearly impossible for the average consumer to figure this stuff out on their own. I don't know if that is the intention, but it certainly is the effect. I have multiple advance degrees in technical fields, as well as a law degree. It took me several hours to parse PG&E's TOU and net metering documents, and I'm still not sure I understand completely.

On the confusion: Agreed. It's a real PITA, but it can be and has been done by several folks, including posters to this forum, usually for their own POCO's, but sometimes for other POCOs as well............................... While somewhat understanding why a POCO may see no benefit to providing assistance or a clear path to help users make sense of any rate tariff, I believe I understand the frustration and confusion of users trying to make intelligent choices. I'd only offer that it is possible. Whether it's cost effective to figure out rate tariffs and decide which is the most cost effective in any particular situation is a separate subject and something of a matter of opinion................... I've often thought that something like an aftermarket may exist for software to help users make sense of the various messes.

[mikenmar]

For readers of this thread who have not yet purchased: Note that being informed about how much electricity you use, how you pay for it, and what options you have that can be the most cost effective ways to reduce an electric bill can pay big dividends.......................................

I will add this: Echoing what another poster said above, PG&E makes it so confusing that it would be nearly impossible for the average consumer to figure this stuff out on their own. I don't know if that is the intention, but it certainly is the effect.

I have multiple advance degrees in technical fields, as well as a law degree. It took me several hours to parse PG&E's TOU and net metering documents, and I'm still not sure I understand completely.

[mikenmar]

On what the installer did, hard to say, but my money's on the installer doing what will help justify, correctly or not, whatever will help sell the largest array possible...............................

I have to say that's not true, actually. They originally wanted to sell me only 13 panels, and I pushed for 14 because I was thinking I ought to cover more of my total usage. At the time, I wasn't thinking about how the TOU pricing would work out.

However, my primary motivation is to reduce my grid consumption for environmental purposes. The amount of money we're talking about is comparatively unimportant to me.

[J.P.M.]

Excellent! But I wonder whether my installer took this into account when they estimated the size of my system. I sent them a spreadsheet with a year of usage data broken down by the hour, but I don't know that they made use of it. I kind of doubt it... I think they just sized it to match total usage. Oh well, as JPM indicates, the utilities are going to change the pricing in the future anyway. In fact PG&E just shifted the pricing of their tiers to charge the lower tiers MORE and the higher tiers LESS -- which makes NO sense from the standpoint of promoting efficiency -- but the PUC let 'em do it anyway... Bah.

On what the installer did, hard to say, but my money's on the installer doing what will help justify, correctly or not, whatever will help sell the largest array possible............................... The pricing shifts you note are the result of AB 327 legislation and its mandated results passed about 18 or so months ago............................ For readers of this thread who have not yet purchased: Note that being informed about how much electricity you use, how you pay for it, and what options you have that can be the most cost effective ways to reduce an electric bill can pay big dividends.......................................

[mikenmar]

You understand correctly. Sdge still has 12-6pm peak on their tou plan, and with my system this time of year, i only need to produce around 60% of what i consume to achieve 100% bill offset. The credits during the day pay for a lot of ev charging at night.

Excellent! But I wonder whether my installer took this into account when they estimated the size of my system. I sent them a spreadsheet with a year of usage data broken down by the hour, but I don't know that they made use of it. I kind of doubt it... I think they just sized it to match total usage.

Oh well, as JPM indicates, the utilities are going to change the pricing in the future anyway. In fact PG&E just shifted the pricing of their tiers to charge the lower tiers MORE and the higher tiers LESS -- which makes NO sense from the standpoint of promoting efficiency -- but the PUC let 'em do it anyway... Bah.

[J.P.M.]

T.O.U. can be used do reduce a bill and also has the capability to reduce initial system size in the way Sensij has done and as he reports. Until recently, that initial size reduction capability has sort of gone unnoticed. Those reductions under T.O.U. seem most effective when existing usage patterns either already have a larger portion of use at times other than "peak" or if/when users choose to adjust their lifestyle/usage patterns to shift usage away from peak times........................ The POCO's, not being stupid, and probably playing heads' up ball, anticipate this as well as beginning to perhaps see some time shifting of peak times of demand as confirmation.....................That's probably one of several reasons why T.O.U. peak times are shifting to the later hours of the day. That shift has picked up steam in the recent past and will probably be subject to continual attempts at flexibility in response to changing influences on usage and pricing....................... I'd not be surprised at efforts to delink what a generator on T.O.U. pays for power from what that generator gets as revenue from the POCO for power generated during similar time periods. Watch for it.

[sensij]

For the two days it's been in operation, I've been getting net excess production as late as 5 pm or so.

Second, prior to 2 pm, I'm still getting partial peak pricing from Monday to Friday. Most of my day usage is on the weekends, and I set my car to charge on off-peak hours.

But I'm not trying to brag, I'm mainly trying to get confirmation for whether I properly understand their net metering pricing policy.

You understand correctly. Sdge still has 12-6pm peak on their tou plan, and with my system this time of year, i only need to produce around 60% of what i consume to achieve 100% bill offset. The credits during the day pay for a lot of ev charging at night.

[mikenmar]

For the two days it's been in operation, I've been getting net excess production as late as 5 pm or so.

Second, prior to 2 pm, I'm still getting partial peak pricing from Monday to Friday. Most of my day usage is on the weekends, and I set my car to charge on off-peak hours.

But I'm not trying to brag, I'm mainly trying to get confirmation for whether I properly understand their net metering pricing policy.

[Mike90250]

Better check again, the books are stacked against you. Peak hours used to end at 5 or 6 pm (1990's) Recently, the utilities pushed them till 9pm.
Your solar harvest will generally fall off at 3pm, or earlier, so don't expect much of your peak offset for that 1 hour, to flywheel you till 9pm!

[mikenmar]

The power company couldn't care about your solar system - the amount produced is meaningless to them - the lost income is of no consequence at all. Don't screw yourself because you mistakenly think the power companies are bad guys.

Lost income is of no consequence to them?? You've got to be kidding.

PG&E proposes far-reaching changes for solar power:

http://www.mercurynews.com/business/ci_28580259/pg-e-proposes-wide-ranging-changes-solar-electricity

[mikenmar]

In case anyone else finds it useful, here's a chart I made showing the summer rates for the E-9A TOU schedule (the kwh prices for the four tiers are at bottom):



I put a copy of this on the fridge for the wife's convenience.

[mikenmar]

I just had my system installed, and I'm waiting to get the sign-off from PGE before net metering starts.

Unlike the OP, I'm on a E-9 TOU schedule because I have an EV. Under E-9, there's no baseline. There are tiers of course, and there are three time periods:

Peak: 2:00 p.m. to 9:00 p.m. Monday through Friday. 3:00 p.m. to 7:00 p.m. Saturday, Sunday and Holidays.

Partial-Peak: 7:00 a.m. to 2:00 p.m. and 9:00 p.m. to 11:00 p.m. Monday through Friday, except holidays.

Off-Peak: All other hours.

For any given tier, rates are obviously highest during peak, less during partial-peak, and lowest during off-peak.

According to the NEM agreement, For an OAS with Time of Use (TOU):

If the eligible customer-generator is a net consumer during any discrete TOU period, the net kWh consumed shall be billed in accordance with that same TOU period in the eligible customer-generator’s OAS.

If the eligible customer-generator is a net generator during any discrete TOU period, the net kWh produced shall be valued at the same price per kWh at the same TOU period in the eligible customer generator’s OAS.

In the event that at the end of the monthly billing cycle, an eligible customergenerator’s net usage for all TOU periods totals zero (i.e. net generation in one or more periods exactly offsets the net usage in all other periods), then the value of usage and/or generation will be calculated using Tier 1 rates (as set forth in the OAS).

My system should generate about 95% of my 600 kwh monthly usage. I will be exporting a substantial amount of power during peak and partial-peak hours, because I'll be at work during the day M-F, and my usage is low in that time period.

If I understand properly, that will work to my advantage. According to the above, it appears net usage/production is calculated for each time period individually, so I should get credited the highest rates for the excess production during peak and partial-peak hours -- is that correct?

[sensij]

btw do you know if SCE and SDG&E calculate the same way as described by wwu123 and devsolar? meaning using a monthly allowance, and assigning proportional baselines for each tou period?
thanks !

SCE and SDGE each have a scheme to divide up the baseline allocation among the TOU periods, but none of the three does it the same way.

With regard to SCE, TOU-D-T is the time of use plan that has a baseline allocation, and a long discussion of the rates can be found in this thread, and in other threads linked within it. This post in particular shows how calculation is handled in the event 2nd tier generation is hit, and was verified against an actual SCE bill.

SDGE doesn't really have a baseline allocation with multiple tiers in any of their TOU plans at the moment. TOU-DR is the closest, with a baseline credit, and you can see their allocation scheme with respect to the baseline in this post.

The recent decision by CPUC on the rate reform proceeding also laid a framework for future rollout of TOU, including more plans with baseline allocations. I don't think there is anything that will force convergence between the IOU's with respect to how baseline allocations / tiered TOU's will be handled, but I am anticipating some new structures between now and 2019 when the default plan for all customers switches from lumped volumetric tiers to TOU.