Tag: "time-of-use rates"


  07:24:00 pm, by Jim Jenal - Founder & CEO   , 455 words  
Categories: All About Solar Power, Solar Economics, SCE, Residential Solar

Clean Power Alliance is Coming - is that a Good Thing?

Clean Power AllianceThe Community Choice Aggregator (CCA) for LA County, Clean Power Alliance (CPA), is set to begin service to SCE customers in 31 cities starting February 1.  As this has just sort of been announced as a fiat accompli with very little information to consumers, we wanted to set the stage for an analysis that we will be publishing that should answer the question - is this a good thing or not?

Let’s start with the basics, what is a CCA? Here’s a definition from an EPA website:

Community choice aggregation (CCA), also known as municipal aggregation, are programs that allow local governments to procure power on behalf of their residents, businesses, and municipal accounts from an alternative supplier while still receiving transmission and distribution service from their existing utility provider. CCAs are an attractive option for communities that want more local control over their electricity sources, more green power than is offered by the default utility, and/or lower electricity prices. By aggregating demand, communities gain leverage to negotiate better rates with competitive suppliers and choose greener power sources.

That means that current SCE customers would still receive their service via SCE (including billing) but the energy is actually provided by the CCA, in this case CPA, at one of three rates: “Lean” (which is 36% renewables and lower than SCE), “Clean” (which is 50% renewables and comparable to SCE), and “Green” (which is 100% renewables and higher than SCE).  Different cities can choose for their residents the “default” rate - for example, Arcadia chose Lean, Alhambra chose Clean, and South Pasadena chose Green - but individual consumers can override that default and pick the rate they prefer.  (You can find the present list of cities switching to CPA and their default rates here.)

However, the only portion of the bill affected is the energy charge, which is generally a smaller component than is delivery.  For example, here is a comparison for SCE customers on the Domestic rate for what they pay now compared to under the “Lean” option from CPA:

SCE Domestic vs CPA Rate

So your savings is about 10% on the first 300 or so kWh (or about $5), but if you make it into the highest tier, your savings drops to just 4.5% on the largest usage.   (Interestingly, SCE’s delivery rates changed a lot more than what is seen in this shift to CPA’s Lean rate.  In particular, the delivery charge for the lowest tier went up by 5.8% as of January 1st, and by 22% for Tier 3 - ouch!)

You can find the complete list of CPA’s rates as of this writing, here.

This Domestic rate is the easiest to review - in a subsequent post we will talk about Time-of-Use rates (relevant to recent and future solar owners) and how to make the right choice to maximize your savings.

Watch this space.



  02:14:00 pm, by Jim Jenal - Founder & CEO   , 347 words  
Categories: All About Solar Power, SCE, Residential Solar, Net Metering

Beware SCE's Attempt to Switch Solar Customers to TOU Rates!


Attention SCE customers who installed solar before the NEM 2.0 deadline (that is, you installed solar before July 1, 2017) - we just learned that SCE is sending around notices suggesting that you switch over to a Time-of-Use rate. You do not need to make that switch, and you most likely don’t want to!
Here are the facts…

SCE customers who installed solar systems prior to the transition to Net Energy Metering 2.0 rules ("NEM 1.0 Customers") are grandfathered into their existing tiered rate structures for 20 years following their go-live date.  While the costs under that rate structure may change, the basic design - a tiered rate where you pay more the more you use, versus a time-of-use rate where what you pay is tied to when you use it - is locked in.  For most solar system owners, that is a better deal.

But we just learned that SCE is trying to convince NEM 1.0 Customers to switch to TOU rates.  (You can find their oh-so encouraging web page for the transition here.)  For the vast majority of solar system owners, such a transition is NOT IN YOUR BEST INTEREST!  The TOU rates have their highest charges either from 4-9 or 5-8, and their lowest charges between 8 a.m. and 4 or 5 p.m.  That means that any energy exported back to the grid will be compensated at the lowest rate (unless your system happens to be exporting after 4 or 5 in the evening, not very likely), whereas energy you need to use in the evening will cost you the most!  

Check out these numbers:

SCE's 4-9 p.m. TOU rate      SCE's 5-8 p.m. TOU rate
SCE’s 4-9 p.m. Time-of-Use Summer Rates   SCE’s 5-8 p.m. Time-of-Use Summer Rates

Yikes!  That’s a whopping 49¢/kWh if you select the 5-8 p.m. rate - but you will only earn 23¢/kWh for energy that you export from your solar system!  Not a good deal at all!

The good news is you don’t have to make this switch!  And if you mistakenly were convinced to switch, you have the right to switch back.  (Similar scams are underway in PG&E and SDG&E territory as well.)  If you have questions, give us a call and we will help you to sort this out.


  04:49:00 pm, by Jim Jenal - Founder & CEO   , 1451 words  
Categories: All About Solar Power, Solar Economics, Residential Solar, Ranting, Energy Storage

Elon Musk's 3-Biggest Powerwall Whoppers

Elon Musk is a visionary and a showman, but occasionally his enthusiasm for his vision gets way out ahead of reality.  Nowhere was that disconnect more on display than this past week when he made his much talked about announcement of the Tesla Powerwall battery storage system.  While we share the vision for the potential of battery systems (such as the one Enphase Energy is set to release later this year, albeit in a far more understated fashion), when 38,000 people go online to order a product that doesn’t yet exist, it is time to debunk some of the more exorbitant claims made by Musk. 

Here are the three biggest whoppers that Musk made during his Powerwall presentation (video below).

Whopper #3 - Power for an ice storm or other significant grid failure event

Musk touted the “peace of mind” that would come from having the Powerwall, and said, “if there’s a cut in the utilities you’re always gonna have power, particularly if you’re in a place that’s very cold, now you don’t have to worry about being out of power if there’s an ice storm.” (See video at 8:35.)

The Powerwall unit that Musk was talking about that was designed for “daily cycling” was a 7 kWh unit that is priced at $3,000.  The average home in the Run on Sun service area uses 25 kWh/day.  So a single Powerwall unit provides roughly one quarter of the energy demand of an average home.  If your desire for “peace of mind” means running your home for a full day in normal fashion, you will need to purchase 4 Powerwall units (assuming you have the wall space to mount them) and that will cost you $12,000.

Of course, many outages last longer than a day.  The longer you want to stay powered, the more units you will need.

Whopper #2 - Powerwall will work with existing solar systems

Musk insisted that Powerwall has been designed to work with solar systems, “right out of the box."  (See video at 8:25.)

Except… that the Powerwall is designed to fit between existing solar panels and the DC-AC inverter(s) in the system (i.e., on the DC side of the system).  But here’s the thing - the vast majority of inverters are what are known as “grid-tied,” which means if the grid goes down, the inverter shuts off, and stays off until the grid comes back.  If the Powerwall is on the DC side, there is no way for it to “mimic” the grid (which, of course, is on the AC side), and so the inverter will shut off.  While the inverter could certainly be replaced with a hybrid inverter (that can work both independently and tied to the grid) such a replacement is a pricey undertaking and certainly not a plug-and-play installation.

But Musk, like the true showman that he is, saved his biggest Whopper for the end…

Whopper #1 - You can go off grid… for $3,500!

Warming to his subject, Musk really brought down the house with his most outrageous claim of all:

You could actually go, if you want, completely off-grid.  You can take your solar panels, charge the battery packs and that’s all you use.  So it gives you safety, security, and it gives you a complete and affordable solution.  And the cost of this is $3,500."  [Gasps and applause from audience.] (Video at 8:55.)

No.  No you cannot.

Let’s unpack his statement.  There’s two major claims here, neither of which is true.  The first is that you could go completely off-grid, and the second is that it would cost you $3,500.  So let’s start with the easy one to disprove, indeed, we already did above: this won’t cost $3,500.  The Powerwall provides 7 kWh of storage.  The average house uses 25 kWh/day.  If the battery has to run your house for just one day, you would need 4 Powerwall units at a cost of $12,000.  (The 7 kWh unit is the one designed for daily cycling - what you need to go off-grid, and it costs $3,000 - if you could actually purchase one, which you can’t.)

So that’s easy to debunk.  But what about the second, more fundamental question.  Can I use this Powerwall system to go off-grid without changing my middle-class, suburban lifestyle?  For most folks the answer is simply, no.  Here’s why.  When you go off-grid you need to be able to meet all of your energy needs all the time without assistance from your local utility.  To do that, you need a battery system large enough to last you during the longest typical shortfall of available energy (i.e., how many stormy/cloudy days in a row will you see), plus a solar array large enough to charge that battery on sunny days while meeting the household needs.  Turns out, that is quite a lot of both.

Folks who design off-grid systems (very few of which are found in areas like Pasadena), typically design for three (or more) days of self-sufficiency (or autonomy, as they put it).  For our typical, 25 kWh/day home, that would require storage of a minimum of 75 kWh.  But according to Tesla, you can only stack a maximum of nine Powerwall units, which limits you to 63 kWh.  Sometime around noon on that third day without sun, your house will shut down.  Oh, and that much storage will cost you $27,000.

What about the solar array side of the equation?  Let’s start by asking how big an array can you fit on an average house?  House sizes have trended bigger in the past couple of decades, so more recently built houses are an overstatement of the average house out there.  Still, to have a starting point (and to give Musk the benefit of the doubt), let’s assume that our average house is 2,400 square feet (a fair estimate based on US Census data), and that it is optimally designed to maximize solar production: a near perfect square with a true south face, pitched at latitude (34° here in Pasadena), with no shading.  Of course, we still have to give the Fire Marshall the desired setoffs so that gets us to 1,115 square feet of roof space (math available upon request), enough for 62 LG 305 solar modules, but because we need to use a hybrid inverter with fixed string sizes, we will drop that down to 60 solar modules. That yields an 18.3 kW system which at $3.50/Watt would cost a cool $64,000 - and be bigger than our biggest ever residential installation. 

So the Sixty-four Thousand Dollar question becomes: How well will that do on meeting our needs?  Per the CSI calculator, this maximal system will produce roughly 29,000 kWh in Year 1, or an average daily output of 79.5 kWh.  (Less in the winter, of course, when you are most likely to see those cloudy days.)  After providing for my daily needs of 25 kWh, I have 54.5 kWh to spare, not quite enough to fully charge my batteries (which require 63 kWh).  A scenario where I have two cloudy days, followed by one partly sunny day, followed by two more cloudy days could easily leave you in the lurch.  And for this you paid a total of $91,000!  If you live somewhere with poorer weather than what we find in the Run on Sun service area (i.e., pretty much the entire rest of the country!) your performance will be even more dismal.

The true value of storage

The sad part of this whole thing is that battery storage combined with solar is going to be huge, but not for the reasons Musk alluded to in his speech.  The future of utility rates is the shift to time-of-use rate structures - a fact already well and painfully known by our clients in SCE territory, and soon to be seen by everyone.  Time-of-use rates, where utility customers pay more for energy during the peak part of the day, are the only way to match utility costs with customer charges.  (It is the head of the Duck in the famous Duck Curve below.)

The famous duck curve

That “overgeneration” that drives down demand at noon is presently fed back to the grid, where the grid operator has to modify the power mix to accommodate it - in essence, it is wasted.  (Although presently, net metering customers get full retail credit for it - something, that in all likelihood, will soon go away.)

But add storage to the mix, and you shift that overgeneration from the middle of the day, to the evening peak hours, benefiting the time-of-use customer as well as the utility.  It is the way to bring about a peaceful end to the utility-solar wars, and it is the true benefit of storage to solar customers - without oversizing either your solar array or your storage system.

So let’s all get excited over solar with storage, but for the right, and much more cost-effective reasons - and not the nonsensical hype being spewed by that super showman, Elon Musk.

Jim Jenal is the Founder & CEO of Run on Sun, Pasadena's premier installer and integrator of top-of-the-line solar power installations.
Run on Sun also offers solar consulting services, working with consumers, utilities, and municipalities to help them make solar power affordable and reliable.

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