Renewables in a hurricane

[WoodyIsGoody]

Agree with your cogent analysis @peakbagger. I think this is why the Powerwall version for backups was withdrawn from the market...it did not do well.

Not really as negative as you make it sound. The original Powerwall was superseded by Powerwall 2 with more capacity, better battery management and upgraded load capacities. You can bet there will be a Powerwall 3 too. It won't be because the Powerwall 2 didn't do well, it'll be because they have a newer, better version. Why would they leave out-dated and superseded technology on the market? Superseded versions are always withdrawn from the market!

Technology marches on! Exactly when it becomes compelling enough to adopt will vary for each individual and mostly has to do with individuals standard of living. Poor people in the inner city will be living with power outages for decades to come. They will just do without when there is a disruption or shortage. For somewhat affluent people, the Powerwall 2 already hits the sweet spot of the cost/benefit curve and is improving their lives as we discuss.

Cheap bastards (like us woodburners) will probably decide to wait for Powerwall 3. Some of us old curmudgeons will swear batteries are no damn good for the rest of our lives as we drive our smoking antique pick-up truck to the gas station and pay $7/gal. to get 5 more gallons to pour into the gas generator under the garage eave. Then we will cuss to find out the gas won't pump because the power is out!

 

[peakbagger]

Thanks for the specs on the Powerwall 2, all previous discussion was on Powerwall (not version 2) which appears to be different beast as it includes the interface electronics I had referred to. Would you care to revise your point to point refutation based on the model we were discussing? Given your typical condescending approach your reply will be interesting.

The limited documentation on the Powerwall 2 link refers to some limited specs on the Energy Gateway. Based on the Green Mountain Power experience the equipment started being distributed in July of this year (after months of delay) and it was one of the earliest installs outside of the founders editions. I was unable to find any companies actually selling Powerwall 2 units. Plenty of references to wait lists. Other sources indicate that it only may work at some point with specific new microinverter based systems that are designed to be compatible with the "energy gateway". Perhaps you would care to post more detailed specs on the energy gateway and what existing PV inverters are compatible with it?

I have no doubt the technology is going to be available at some point in the future but excuse me for not being familiar with what was vaporware until a few months ago. Probably an option for someone thinking of installing a system in the future to go along with their Power Roof with its associated high cost premiums.? I distrust bleeding edge marketing that Tesla uses, generally the marketing is announced long before the actual product is available and frequently the specs change significantly before it actually hits the street. Reportedly both the future Powerwall and Solar Roof vaporware has been used to generate sales leads for high pressure PV installations, apparently the salesmen make some sort of verbal assurance that at some point in the future the equipment installed will be compatible. Meanwhile someone gets sucked into an overpriced leasing arrangement justifying it with some future capability.

I rarely if ever would recommend someone buy early product with a limited installed base on the street, I let it be on the market for awhile and let the early adopters with money to burn to work the bugs out. Feel free to write the check and tell us how it worked in the long run.

By the way, this is not a theoretical discussion for me, I designed and installed one of the earlier grid connected PV systems long before it got popular in my state and have done the same with two other systems at home and helped with the design on several successful installs. I also do it for a living on large industrial scale and have over 10 megawatts of installed multimode systems that can run both grid synchronous and isochronous and several more either in the process of being installed or in early stage. If I could justify the need for PV based backup power system I would be the logical person advocating it but the reality is the cost benefit is not there for most, maybe it will be in the future. The reality in my area is extended power outages happen to occur in the winter when we can go days without appreciable solar production. I am far better doing a generator/battery solution with PV contributing what it can. That's readily doable with conventional off grid equipment like Outback which actually publishes detailed specs. Maybe the Energy Gateway will have the capability but I cant tell as I cant find any detailed specs.

 

[WoodyIsGoody]

Thanks for the specs on the Powerwall 2, all previous discussion was on Powerwall (not version 2) which appears to be different beast as it includes the interface electronics I had referred to. Would you care to revise your point to point refutation based on the model we were discussing? Given your typical condescending approach your reply will be interesting.

Wow, sorry if you feel my approach is "condescending". I found your approach dismissive and condescending. But I can take it. On one hand you brag that you have installed/designed numerous residential PV systems over several years and are currently an active professional in industrial scale PV design or install of many megawatts with numerous projects in the pipeline. On the other hand, you were unaware that the Powerwall 2 was available and had the capacity to power simple things like domestic water pumps and thought the maximum surge capacity was less than half of what it is and that Tesla didn't publish specs for equipment they sold. It's difficult for me to imagine how a professional PV engineer could be so oblivious to what's been going on over the previous 12 months. But I guess when you're surrounded by big commercial installations one might tend to be dismissive of what's going on in residential (even if that was your start into PV systems). Fair enough.

If you want to learn more about what's involved in an AC Powerwall installation this is a good video:

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For off grid installs there is the DC Powerwall. And unless you have a huge PV installation, you would want a back-up generator to keep the system charged during unfavorable conditions if you didn't live in a reliably sunny climate. Common sense really. But in an extended outage, a "prepper" would just prioritize energy usage so they always had enough for critical systems. The Powerwall adds significant efficiency to a generator because generators are horribly inefficient when running light loads or idling. You can also run a smaller generator and let the Powerwall take care of peak loads. And you can consume energy during "quiet hours" without the generator running, all significant advantages. Of course this is still in it's infancy and I'm not trying to say it's economic unless you have expendable income and want the kind of security these systems can provide your family. But it is a much better deal than lead-acid batteries which require maintenance and replacement in 3-5 years. The Powerwall is also handles deep discharge better, which is how these systems are used. And 13.5 kWh of lead-acid is not going to give you 7kW of surge power and they are going to weigh tons.

Perhaps you would care to post more detailed specs on the energy gateway and what existing PV inverters are compatible with it?

That is beyond my knowledge. But as a commercial PV system engineer, surely you know you can call Tesla and ask them for an authorized distributor list or connect with their own in-house engineers to answer your questions. Oh, I forgot, you don't trust them to give accurate answers...I guess you had better stick with lead acid. If it was good enough for 1920, it's gonna work just fine in 2020!

And please don't take offense at that last comment, it's just light-hearted poking at your anti-Tesla bias. Nothing personal.

 

[woodgeek]

Well, I'm still confused.

I looked at this tech back when the two Powerwall (1) systems ('solar' and 'backup') were announced. I had seen the recent Kryten video you posted re Powerwall 2, which at ~20mins in says that the system shuts down completely during a grid outage. So that is not going to do what you say. You mention the DC Powerwall 2...so I had to look that up....

https://www.solarquotes.com.au/blog/tesla-kills-off-dc-powerwall-2-ac-version-delayed/

Looks like the DC Powerwall is not for sale outside the US, and the same article says the AC Powerwall 2 can (suitably wired with a disconnect, I assume) provide backup power, but that the battery CANNOT be recharged from the PV or a genny. This is great for a short outage, but not the same functionality as an islanded PV system OR an off-grid system.

I could not find any usage of the DC Powerwall 2 for islanded PV using The Google. That functionality does not appear to be currently offerred by Tesla....do you know otherwise?

Of course, when I am not shilling for Big Oil, I am 'like'ing Tony Seba videos...so I believe that everything you describe will be available and cheap, and probably from Tesla at that, but that does not seem to be the case YET. Sometimes with the future the waiting is the hardest part.

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[iamlucky13]

Tesla sized the Powerwall 2 for reasonable single family residence needs. If you have a huge family or special needs you might need two or, God forbid, 3 of them. But one would suffice for normal residences designed to not be electrical hogs.

It really depends what you're trying to accomplish and for solar integration how well your demand aligns with your supply. If you play with the form on Tesla's website, for a 3-bedroom house (they indicate 30 kWh per day average demand, which is in line with figures I've seen from the DOE), and want to be 100% grid independent, they recommend 10 kW of solar and 4 Powerwalls. They don't seem to say what their reference location is. They figure with 2 Powerwalls, you could be 98% independent. I'm guessing those percentage figures indicate days when your supply falls short, and the reference location plainly has fairly consistent sun.

Of course, most off-grid folks focus a lot more on conservation, and would likely be shocked at the thought of trying to go off-grid while using 30 kWh per day.

When I started calculating what it would take in my area (Pacific NW) however, I was floored. The folks who share data on what their solar panels produce were really helpful, and when you see 3-4 days stretches where the production drops by 90% due to heavy overcasts, it really does a number on your panel requirements and your storage requirements. I don't think I saved my calculations to look up again, but it was something like $100,000 for my 3-bedroom, 80's construction house, with a heat pump. And I was using cheaper batteries in my calculations than the Powerwall.

I will note, however, the nominal longevity of high quality, well-managed lithium-ion batteries should bring the long term cost roughly on par with maintenance free lead acid batteries - you pay more up front, but the Powerwall should last longer.

 

[WoodyIsGoody]

I could not find any usage of the DC Powerwall 2 for islanded PV using The Google. That functionality does not appear to be currently offerred by Tesla....do you know otherwise?

Hey, Tom Petty is awesome. But why wait?

Here's an example of how the Powerwall 2 can be used for power failure (or entirely off-grid). Tesla has made it so it's not rocket science:

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[WoodyIsGoody]

It really depends what you're trying to accomplish and for solar integration how well your demand aligns with your supply. If you play with the form on Tesla's website, for a 3-bedroom house (they indicate 30 kWh per day average demand, which is in line with figures I've seen from the DOE), and want to be 100% grid independent, they recommend 10 kW of solar and 4 Powerwalls. They don't seem to say what their reference location is. They figure with 2 Powerwalls, you could be 98% independent. I'm guessing those percentage figures indicate days when your supply falls short, and the reference location plainly has fairly consistent sun.

Of course, most off-grid folks focus a lot more on conservation, and would likely be shocked at the thought of trying to go off-grid while using 30 kWh per day.

Exactly! We are very wasteful of electricity and conservation is an important part of being willing to go off-grid unless you have money to burn. Even then, going off-grid is not to save money, it's for other reasons. Some people like they are not participating in the consumption of electricity generated in a "dirty" manner with regard to AGW and human health. Others like the security of providing their own and never having a power outage. And some remain connected to the grid but only draw during slack demand.

When I started calculating what it would take in my area (Pacific NW) however, I was floored. The folks who share data on what their solar panels produce were really helpful, and when you see 3-4 days stretches where the production drops by 90% due to heavy overcasts, it really does a number on your panel requirements and your storage requirements. I don't think I saved my calculations to look up again, but it was something like $100,000 for my 3-bedroom, 80's construction house, with a heat pump. And I was using cheaper batteries in my calculations than the Powerwall.

Yeah, off grid systems typically don't try to heat big loads using electricity! Because heating loads peak when solar energy is at a minimum. So wood heat makes the most sense.

I will note, however, the nominal longevity of high quality, well-managed lithium-ion batteries should bring the long term cost roughly on par with maintenance free lead acid batteries - you pay more up front, but the Powerwall should last longer.

Yes, a lot longer.

 

[woodgeek]

Hey, Tom Petty is awesome. But why wait?

Here's an example of how the Powerwall 2 can be used for power failure (or entirely off-grid). Tesla has made it so it's not rocket science:

Digging into the comments, I learned that the 'energy gateway' that does the switching and isolation is a separate Tesla product (not sold in a spiffy LED illuminated box).

I think the lack of consumer support here is b/c each system is intended to be engineered and installed by a local tech, in a manner that varies with the users current wiring/solar setup. It would not be possible to come up with a 'one size fits all' system, given the broad range, age and complexity of different retrofit and new solar installs possible....not to mention sizing and use cases.

The BIG question is availability of US installers....we have seen videos from the UK and OZ, but none from the US yet...what gives?

 

[WoodyIsGoody]

The BIG question is availability of US installers....we have seen videos from the UK and OZ, but none from the US yet...what gives?

My best guess is that the US has the most negative (and inexplicable) distrust and bias against solar power of any country I'm familiar with. When a company is releasing a new product they spent millions developing, they want to make sure the initial users have realistic expectations that are matched to published product capabilities. All other countries tend to have residents that are more energy conscious, more conservation orientated and more informed than Americans. If Tesla released it first in the US, I can think of some negative consequences (from the companies perspective):

Ignorant consumers bitching that the battery couldn't make it through the middle of the night whether it was due to the electrical heat tape covering all their exposed plumbing, an electric water heater feeding a dripping faucet or the block heater keeping their diesel truck from freezing during a Minnesota winter or the electric space heater keeping their uninsulated garage at 55F or a combination of little boneheaded energy "blunders". Some people just don't understand supply and demand very well, they want everything to be unlimited and, when they fall short, they will blame the product. I'm an American myself but I have to call it how I see it, on average, Americans have this "entitlement" attitude when it comes to energy that is not well grounded in facts and that most people around the globe do not share.

The US has a very loud and vocal support of the fossil fuel industry compared to other countries like those in the UK, EU and AUS. Many Americans have been brainwashed to believe that cheap energy and wasting energy is somehow a very good and powerful thing, very American, very patriotic. When releasing a new product, a product that assumes the user understands it's published limitations, this can create very negative (if unwarranted) publicity. When a new product has more demand than supply, it is simply good business to release the early units into the markets that will put your product in the best light.

The above is just my speculation but I do know that Tesla is run by very bright, very aware and forward thinking people. It would be odd if they didn't take the dynamics of these regional differences into account when releasing new products that are production constrained. It is not true that all publicity is good publicity.

 

[woodgeek]

I think we'll have to agree to disagree.

The US rooftop PV penetration is not as high as in OZ, but total PV (rooftop and utility) capacity is large and growing quickly. Also Tesla has a whole subsidiary (formerly SolarCity) that does complete PV installs from the ground up, in many markets across the country. I guess I could buy your argument for some states that are outright hostile to solar....but Tesla finds the legal/political environment too anti-solar or the customer base too small in say, California, to sell this product there?? When grid failures are more common in the US than in almost any developed country?

 

[georgepds]

For those of us in the dark about OZ:

When Aus or Aussie, the short form for an Australian, is pronounced for fun with a hissing sound at the end, it sounds as though the word being pronounced has the spelling Oz. The word Australia when referred to informally with its first three letters becomes Aus.

 

[WoodyIsGoody]

I guess I could buy your argument for some states that are outright hostile to solar....but Tesla finds the legal/political environment too anti-solar or the customer base too small in say, California, to sell this product there??

Uh, no. Please re-read what I wrote.

I didn't say Tesla WOULDN'T sell the Powerwall in the U.S., I simply supplied logical reasons why they might send initial production to areas that are more solar friendly first.

 

[begreen]

Are they able to keep up with demand or are these units on backorder? Just wondering how they can produce enough to keep up with their industrial demands and production requirement of the Tesla 3.

 

[georgepds]

Not to mention that big battery in OZ

 

[begreen]

Not to mention that big battery in OZ

That was one of the industrial projects I had in mind.

 

[WoodyIsGoody]

Are they able to keep up with demand or are these units on backorder? Just wondering how they can produce enough to keep up with their industrial demands and production requirement of the Tesla 3.

That's a good point, the Powerwall, the utility grade Powerpack and the Model 3 all compete for the same cells. Tesla has already done big, utility scale battery installs in Kauai and California (and perhaps others I haven't heard about). One project in CA has enough batteries to power 15,000 homes over the 4 hour peak demand period.

Today I visited Tesla Chat Help to inquire about availability of Powerwall 2 in the US. Unfortunately, they don't have certified installers available in my zipcode (until this October) but they did confirm they are installing them in other areas of the US and that they can be used for back-up power when the grid is down.

This is a huge ramp-up and it takes time to get all the teams trained and put into place. But I do think they are making cells as fast as their production facilities allow and are production constrained. I don't think their Gigafactory is anywhere near it's planned production capacity. They have got the entire machine turning, just a matter of steadily increasing output and building up sales/installation networks (not to mention supply chains, etc).

 

[begreen]

The planned growth and size of the gigafactory is staggering. Musk thinks big, very big. Reno must love him.

 

[iamlucky13]

Not to mention that big battery in OZ

It used a net capacity of cells roughly equivalent to the Model X production last month, and if I remember right, they're using a different chemistry for stationary power applications, so it shouldn't directly impact cell availability for EV's.

What was most interesting about that is the delivery timeline, which suggests to me they were probably already stockpiling the modular units in anticipation of upcoming sales.

The planned growth and size of the gigafactory is staggering. Musk thinks big, very big. Reno must love him.

The size committed to at the moment is roughly proportional to their planned production ramp-up so far, and they want to grow in other markets, too, including stationary power.

If EV's really do track towards sales volume parity with ICE's by a 2040-2050 timeline, a huge amount more capacity will be needed.

He's definitely put a lot of money at risk, but I assume they're also holding a lot back until they see how fast the market actually grows, as well as to preserve their capital and credit for the challenge of their ongoing production rampup.

 

[WoodyIsGoody]

It used a net capacity of cells roughly equivalent to the Model X production last month, and if I remember right, they're using a different chemistry for stationary power applications, so it shouldn't directly impact cell availability for EV's.

As I mentioned in my previous message, the exact same cells are used in the Model 3, Powerwall 2 and Powerpack 2.

If EV's really do track towards sales volume parity with ICE's by a 2040-2050 timeline, a huge amount more capacity will be needed.

EV's at volume parity with ICE vehicles by 2040-2050? LOL! We'll see but I think you're likely to be about 10-20 years late!

 

[woodgeek]

I too recall hearing that the cells in the 'AUS' array were not from the Gigafactory.

 

[WoodyIsGoody]

I too recall hearing that the cells in the 'AUS' array were not from the Gigafactory.

Being production constrained and due to the size of the install down under, maybe Tesla sourced cells elsewhere as a stopgap measure. But the Powerpack 2 and Powerwall 2 are Tesla's primary stationary storage solutions and both are outfitted with the same cells found in the Model 3.

 

[Seasoned Oak]

We do have a member from southern florida (Where2)with lots of solar panels ,anyone heard from him???????????????

 

[WoodyIsGoody]

We do have a member from southern florida (Where2)with lots of solar panels ,anyone heard from him???????????????

I haven't, I hope they're ok!

Here's a fairly comprehensive answer to the original question (at least with respect to PV in hurricanes):

https://solarpowerrocks.com/solar-questions/happens-solar-panels-hurricane/

 

[Where2]

We do have a member from southern florida (Where2) with lots of solar panels ,anyone heard from him???????????????

No, you haven't heard from me. Probably because I was off dealing with Hurricane Irma, 60 hours without grid power, cleaning up my yard for two days, and processing avocados.

Technically, I have one of the smaller arrays at only 4.4kW (twenty 220W panels). For backup power, I have a 5,500W (big box store) gas generator.

When the power eventually went out (Sunday at 4:40PM), we quickly dumped the food from the side-by-side freezer and fridge into the Engel MT-60 and MT-27 refrigerated chest coolers respectively. Both units were pre-chilled on 120V power, until the grid dropped out. Prior to the storm, our neighbor offered us an outlet for an extension cord (12AWG) off the inverter he was running from his Ford Powerstroke parked in front of his garage. My kill-a-watt said the output was a square wave inverter, but the conversion system in the Engel refrigerators didn't seem to care. The two Engel units were drawing a peak combined of under 150W. The neighbor's quiet backup system lasted until one of the leads to the battery off the neighbor's truck came loose in the middle of the storm, which was sometime in the middle of the first night. Monday morning, I pulled out our trusty 5.5kW generator (bought after Hurricane Frances in 2004) that I had last used after Hurricane Wilma in 2005. I started by disassembling the carburetor after sitting for 12 years. There was minor varnish in the float bowl (it was drained of fuel and run until it stalled out, prior to leaving it sit in the garage for 12 years), so I carried the carburetor over to my father's house to use his compressor to blow the tar out of the passages. (Dad's got an Onan in his Winnebago, so he had power for tools, you just had to pick what you wanted to run) My 5.5kW generator spent a good portion (75%) of the next 48 hours running a consistent 1.8kW-2.2kW load. That load was the main side-by-side fridge, the two Engel refrigerated coolers, a 12,000Btu roll around single hose A/C unit, and an occasional load of laundry through the Samsung front load washer. I used my TED 5000 to keep track of current/wattage drawn off the generator.

Just a few hours prior to losing power, I had turned up the hot water heater, and it was up to 137°F when the grid failed. It was only 117° when the grid returned 60 hours later... That was after a few showers from the wife and I. At close to 2kW load, the gas generator burns ~0.5 gallons per hour. Our neighbors across the street had power restored Monday morning. Other people on their side of the block still didn't have power when I got home from work tonight (Friday night). It took 10 days after hurricane Frances to get power back on our side of the street, so I am familiar with how brutal it can be to live without it.

If you're wondering about the Engel refrigerated coolers: my thought was I could run them off 12V deep cycle batteries out of one of our boats for extended periods of time if necessary, and recharge the batteries off the generator. As it turned out, it was so incredibly hot and humid the two days and nights that we were without power that my wife spent most of the time parked in front of the roll around A/C unit which only managed to get the room it was operating in down to 80°F at best. Monday night, we both slept on the terrazzo floor (without A/C) to keep cool. The 12V 0.45A PC muffin fans run off a 7Ah battery for several hours...

Thoughts in retrospect: 400W of PV panels coupled to a MPPT charge controller and a 12V battery would run the two refrigerated Engel coolers indefinitely. Making your own 120V power runs around $0.85/kWh. The 48 LED (5050 chip) panels I bought off eBay generate an incredible amount of light, if only my house had a centralized 12V wiring system to accommodate running some 12V items like fans and lights. At some point, I need to build an integrated power monitoring system into the generator or the house power inlet. And finally, I need to devise a 9V (dc) backup system for the Davis Weather Wizard III to keep track of the winds.

In the end, we are safe with NO damage to the house, despite dropping a large royal palm frond directly on the PV array in the midst of the storm. Mostly minor damage to our 5 avocado trees in the yard. We did harvest our entire crop of >100 large Luna avocados on the day before the storm. Despite giving away dozens of avocados, I now have 10+ quart sized bags of frozen avocado paste in the freezer to make guacamole for months to come. The fruit keep for weeks on the tree, but ripen within 3-5 days of being picked off the tree. This morning, my wife spent 3+ hours processing ripe avocados into frozen paste. At some points in the forecast cones it looked like we might be getting the brunt of a Cat 4 or Cat 5 storm. In the end, it came in the west coast as a Cat 3 (we are on the East Coast), and we really didn't test the 170mph wind rating on my array's attachment to the second floor roof.

 

[Seasoned Oak]

Good to know your all safe W2 ,i figured you were busy and would give us a heads up when you had a chance. Iv got family in Coco ,power stayed on for them. They got lucky .