Category: Ranting

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05/10/15

  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.

03/28/15

  04:00:00 pm, by Jim Jenal - Founder & CEO   , 361 words  
Categories: All About Solar Power, Residential Solar, Ranting

Who has the Edge? 3 Reasons to Pick Enphase over SolarEdge

SolarEdge has gotten a fair amount of buzz this week thanks to their IPO, but it made us think that maybe it was time to revisit the question—who really has the edge: DC-to-DC “optimizers” like SolarEdge or Enphase microinverters?

Enphase Microinverter Which would you choose? Solar Edge Optimizer
 Enphase Microinverter    SolarEdge Optimizer

 

In our view this is a bit of a “no-brainer” and it really comes down to the following three reasons:

Reason #3 - Integrated Grounding — In every solar array, all metal surfaces have to be grounded for safety.  Enphase microinverters now feature integrated grounding, which eliminates the need for a separate equipment grounding conductor.  SolarEdge does not have this feature and, depending on the jurisdiction, may require the use of a dedicated copper conductor to be run from one unit to the next.  This increases both labor costs as well as part costs (copper is expensive these days!).  Far better to have that grounding built-in at the factory than assembled on the roof.

Reason #2 - Easier Installation — Beyond the need for that equipment grounding conductor, the SolarEdge system requires the installer to not only mount the optimizers on the roof beneath each panel, but it also requires the installer to mount one or more heavy (51 to 88 pound) inverter(s) on the wall.  In contrast, Enphase combines everything into one unit, so there are no heavy inverters to mount to the side of the client’s house.

Reason #1 - Greater Reliability —The number one reason for us at Run on Sun is the greater reliability you get from using Enphase.  Frankly, the SolarEdge approach combines the worst of both alternative approaches (i.e., string inverters versus microinverters).  You are still putting power electronics in the demanding environment of a roof, AND you have combined that with a single point of failure with the inverter back on the ground!  When you use Enphase microinverters you eliminate that single point of failure and you are going with the industry leader in creating reliable, roof-mounted power systems.

Put all of that together, and we think Enphase microinverters provide the greatest value to our clients, which is why we feature them in all of our solar power systems, despite the occassional “buzz” other approaches might generate.

02/05/15

  08:07:00 am, by Laurel Hamilton, Projects Coordinator, Run on Sun   , 364 words  
Categories: Solar Economics, Solar Tax Incentives, Ranting, Solar Policy

President Obama: Extend Solar Tax Credit... Congress: Don't make me laugh!

Two weeks ago I included the looming 2016 expiration of the federal Solar Investment Tax Credit (ITC) as one of the “Top 5 reasons you shouldn’t wait to go solar“. The 30% ITC rebate for residential and commercial solar projects is slated to drop to 10% for commercial projects (effectively stopping utility-scale solar growth) and to zero for residential projects (making going solar much less feasible for many homeowners). I mentioned that the likelihood of an extension is far from certain given our partisan federal ‘climate’.White House Flickr Photostream

Then…on Monday the White House released President Obama’s fiscal budget for 2016. To my delight the budget includes:

  1. Boosting clean energy funding to $7.4 billion;
  2. The Clean Power State Incentives Fund allocating $4 billion to encourage states to exceed the minimum requirements for cutting emissions; and
  3. The permanent extension of the solar Investment Tax Credit!

The $7.4 billion figure is up from the $6.9 billion proposed in Obama’s fiscal 2015 budget, a 7.2 percent rise, and over the $6.5 billion actually passed by Congress for this year. The extension of the ITC and further state incentives to reduce emissions would be immensely valuable to keep the ball rolling in the solar field. Given that solar is booming - providing over 170,000 living-wage jobs and eliminating over 13 million metric tons of harmful CO2 emissions in 2014 alone - it makes sense to continue to incentivize. 

However, it may come as no surprise to hear that some lawmakers have said they plan to block the President’s budget priorities entirely. An article in Politico titled “Republicans: Obama Budget ‘Laughable’” cites many congressional Republicans disdain for the budget.

“Obama’s budget is a retread of past proposals that died instantly on the Hill.”
Senate Finance Committee Chairman Orrin Hatch (R-Utah)

The website www.gop.gov cites the singular case of Solyndra as definitive evidence to oppose funding clean energy…despite also claiming to support job growth. (See here as to why Solyndra just doesn’t matter.) With Republicans now controlling both the Senate and the House of Representative, this party line opposition will be a serious challenge to overcome.

Even with the President himself in favor of extending the ITC, and improving funding to support clean energy, the fate of federal support for the solar industry is still quite uncertain.

Watch this space.

12/17/14

  05:39:00 pm, by Laurel Hamilton, Projects Coordinator, Run on Sun   , 564 words  
Categories: All About Solar Power, Electric Cars that Run on Sun, Climate Change, Ranting

Misinterpreted Study Leads to Negative News for Electric Vehicles

Run on Sun gets a new Volt!There’s a good chance if you’re reading this blog you either have hopes of someday owning an electric vehicle (EV) or you are one of the proud individuals already enjoying cruising silently by gas stations…such as Run on Sun’s Jim Jenal in our new Volt pictured on the right! In either case your ears likely perk up at any breaking news regarding EVs.

Over the last few days I’ve noticed alarming headlines coming from multiple sources. While the key word in headlines such as “Study Finds Electric Cars May Not Be Very Green at All” is “may“, many of the articles state definitively that electric cars are not as green as gasoline cars. I decided to investigate.

On December 15th a new study by the University of Minnesota was released to the press. The study calculated the air quality impacts of manufacturing and refueling vehicles with various forms of power. Below is the study’s abstract verbatim:

We evaluate the air quality-related human health impacts of 10…options, including the use of liquid biofuels, diesel, and compressed natural gas (CNG) in internal combustion engines; the use of electricity from a range of conventional and renewable sources to power electric vehicles (EVs); and the use of hybrid EV technology.

…We find that powering vehicles with corn ethanol or with coal-based or “grid average” electricity increases monetized environmental health impacts by 80% or more relative to using conventional gasoline. Conversely, EVs powered by low-emitting electricity from natural gas, wind, water, or solar power reduce environmental health impacts by 50% or more. Consideration of potential climate change impacts alongside the human health outcomes described here further reinforces the environmental preferability of EVs powered by low-emitting electricity relative to gasoline vehicles.

Did you catch that last part? Electric vehicles, charged by low-emitting electricity (anything but coal) are preferable environmentally alongside human health impacts…to gasoline vehicles. A far cry from the grossly misinterpreted ‘electric cars aren’t green’. Which is simply not what the study says.

The straightforward lessons from the study include three main points:

  1. Electric cars powered directly from the grid have the awesome bonus that they get cleaner as the grid does. Whereas gasoline vehicles have the same or worse carbon footprint for the lifetime of the car.
  2. If your car is charged on the coal-heaviest grids, it causes almost twice as many deaths from air pollution compared to gasoline vehicles. However, I’d like to note that electric car adoption is negligible in the states with the dirtiest grids. In addition, with EPA regulations on existing power plants, much of the coal generation (currently less than 40% of US electricity generation) will be retired in favor of cleaner energy in the next 20 years.
  3. But if you recharge on a natural gas-based grid the EV produces only half the pollution-related health problems as the gas guzzler. Recharge on renewable energy – whether from a grid or derived from home solar panels – and EVs produce just one quarter of the health problems!

In summary, don’t get an electric vehicle if you’re planning on charging it off of a coal-powered grid. Do get an electric vehicle if your grid is sufficiently green… or better yet, use a solar power system designed specifically with charging your EV in mind – see Run on Sun’s website for info! And remember that facts are frequently misinterpreted by the press. When in doubt, read the actual study, not just the headlines.

12/02/14

  09:44:00 am, by Laurel Hamilton, Projects Coordinator, Run on Sun   , 571 words  
Categories: Climate Change, Ranting

Demystifying EPA’s New Smog Regulations

The New York Times, Washington Post and other national media all weighed in on a historic, yet divisive, announcement from the Environmental Protection Agency (EPA) just before the Thanksgiving holiday. As part of the Obama administrations’ enforcement of the Clean Air Act the EPA proposed a regulation that would lower the current limit for ground-level ozone pollution to 65-70 parts per billion (ppb) with a possibility for seeking a standard as low as 60 ppb. This in line with what independent scientific advisory panels have been recommending since 2008 when the current level was established at 75 ppb. The EPA had planned to release the rule in 2011 but the Obama Administration decided to delay due to election year jitters and the President preferred to wait until the economy was in a better condition to handle the economic blows that would result. Some may believe this is an issue being pushed by the Obama administration, but the 1970 Clean Air Act requires that these air regulations are revised based on the scientific evidence every five years.

Ozone description from Airnow.govThe proposed standard is referring to ground-level ozone everyone in Southern California knows as smog or the infamous “haze”. As we are also painfully aware, smog is caused by emissions of pollutants which come from a range of sources including cars, power plants, air traffic, manufacturing plants, and oil and gas refineries. Ozone in the air we breathe is very harmful triggering a variety of effects such as asthma, chest pain, heart and lung disease, and premature death – particularly in children, the sick, and the elderly. For sunny Los Angeles this is no small matter since ozone causes the most damage during hot sunny days. As such, the updated standard is meant to be a public health measure and does not include direct regulation on businesses. The new rules will expand the ozone monitoring season and update the Air Quality Index to keep people informed when pollution levels are dangerous.

The fossil fuel industry, manufacturers, and their allys criticize the new standards stating they will wreak havoc on the economy. Some even calling it the “costliest regulation ever”. Indeed, power plants and factories will need to install expensive technology to clean up their pollution emissions. However, advocates argue that the economic benefits - measured in reduced health care needs and increased productivity due to improved health - significantly outweigh the costs to industry. States also have a very generous time, up to 23 years, to comply. Though some regions, including Southern California are not even complying with the 1997 standard of 84 ppb yet.

EPA administrator, Gina McCarthy, stated “Bringing ozone pollution standards in line with the latest science will clean up our air,…protect those most at-risk”, and the American people “deserve to know the air we breathe is safe.”

This is what improving regulations on air quality is all about. Though smog levels have been declining steadily over the last 40 years, there are always costs and benefits to each incremental improvement. As populations in urban centers continue to grow, these reductions in allowable pollution levels are always going to be both more difficult to accomplish and more imperative to preserve human and environmental health. Most would agree that human and environmental health trump the economic health of industries, especially industries that now have many viable solutions to damaging practices. Getting regulations in line with scientific evidence is just one more way to remind industry of how their environmental impacts are affecting the rest of us.

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

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