AC Coupled Systems

[ramsy]

I'll much more readily believe they can be made safe in that location than that they will have a long enough life to justify that choice economically compared to other options.

If warranty period is somehow misrepresented, forcing free replacements, CEO's can lose bonuses, if not their jobs.

 

[jaggedben]

If warranty period is somehow misrepresented, forcing free replacements, CEO's can lose bonuses, if not their jobs.

First, that will be, like, 8 years from now. I've noticed that CEOs of startups often don't account for risk on such a timescale.

Second, I don't think 10 years is a competitive warranty for LiFePo energy storage.

 

[tallgirl]

They choose not to use active-cooling electronics, fans, or liquid convection, as their rivals do, but could always ad it later.

Apparently, with passive thermal, lithium-phosphate chemistry, and satellite-aerospace engineering bluster, their 96% efficiency don't need no stinking cooling.

They use the energy density inherent in phase changing, but if the material doesn't change back, they are just screwed. This is the fly in the ointment --

wherein a melting temperature of the PCM is selected based on an operating parameter or ambient temperature profile of one or more of the plurality of charge storage components; and

They have to get rid of the Latent Heat of Fusion into the environment or else the "PCM" doesn't change back to the solid phase.

 

[pv_n00b]

Don't know how these panel batteries got engineered for -4 to 150°F operating temperatures, NRTL tested for UL9540, UL1973, with a standard 10 year warranty, but apparently they work fine right next to the micro-inverters.

Do they plan on being out of business in 5 years when all the batteries start coming back for warranty replacement? A warranty is a promise to replace a defective product, not proof that something will work for a given period of time. And promises have been broken.

 

[tallgirl]

Do they plan on being out of business in 5 years when all the batteries start coming back for warranty replacement? A warranty is a promise to replace a defective product, not proof that something will work for a given period of time. And promises have been broken.

I've worked for companies that had full product recalls in well under the warranty period. There are testing models which can predict life expectancy, but they work best for products where failures are well-understood.

Since we're in the PV forum, some of y'all may remember Potential Induced Degradation, which I don't think manufacturers even knew was a thing.

 

[ramsy]

First, that will be, like, 8 years from now. I've noticed that CEOs of startups often don't account for risk on such a timescale.

Second, I don't think 10 years is a competitive warranty for LiFePo energy storage.

If passive thermal micro-battery design can't support the warranty, there's room for active cooling down the road.

When JLM Energy miss-managed payrolls & ran out of money, others continued to improve on the 2014 micro-battery development.

The torch is being passed on, rebuilt, and made better than before. This genie is not going back in the bottle.

Attaching micro batteries to solar panels removes complex DC-AC-DC charge cyle switching, equipment, raceways, simplifies installation & inspections.

Chetty Bang-Bang LiFePo systems are relatively inefficient & complex.

 

[ramsy]

I've worked for companies that had full product recalls in well under the warranty period. There are testing models which can predict life expectancy, but they work best for products where failures are well-understood.

Since we're in the PV forum, some of y'all may remember Potential Induced Degradation, which I don't think manufacturers even knew was a thing.

Warranty fulfillment cost nothing for the customer.

 

[ramsy]

Do they plan on being out of business in 5 years when all the batteries start coming back for warranty replacement? A warranty is a promise to replace a defective product, not proof that something will work for a given period of time. And promises have been broken.

Current design being discussed is passive thermal.

Active cooling is always available, but not necessary, yet.

 

[tallgirl]

Warranty fulfillment cost nothing for the customer.

Unless the business is no longer around to fulfill the warranty.

I'm not suggesting they won't be around, but having looked at their patent, I'm not convinced the technology is appropriate for high ambient temperature environments. In particular, I'd like to see what temperature profile they've designed for to ensure the "PCM", which they say is a paraffin in the ideal embodiment, returns to the solid phase each day.

 

[jaggedben]

...

Attaching micro batteries to solar panels removes complex DC-AC-DC charge cyle switching, equipment, raceways, simplifies installation & inspections.
.

As far as I can see it only removes one conduit, and replaces that with the hassle of getting a lot of heavy and delicate components to the roof, and the hassle of working on the roof if... I mean when ... they need servicing. I was curious if wiring communication would also be a hassle, but it's s wireless. So they've sacrificed reliability for installation speed there. Yuck. Enphase made that mistake and it sucks but at least with them it's only a few batteries in each system.

I mean, they might have a commercial market, and good luck to them. But I'll believe it when I see it.

 

[tallgirl]

As far as I can see it only removes one conduit, and replaces that with the hassle of getting a lot of heavy and delicate components to the roof, and the hassle of working on the roof if... I mean when ... they need servicing. I was curious if wiring communication would also be a hassle, but it's s wireless. So they've sacrificed reliability for installation speed there. Yuck. Enphase made that mistake and it sucks but at least with them it's only a few batteries in each system.

I mean, they might have a commercial market, and good luck to them. But I'll believe it when I see it.

All of the products I know of use some form of power line communication, whether it's AC or DC power.

I did work on one product -- a string monitoring product which was neither power conversion nor power optimization -- which used a proprietary Zigbee mesh, but powerline communication is very old technology. Apparently utilities transmit internetworking traffic on the pilot lines for their own purposes.

 

[jaggedben]

All of the products I know of use some form of power line communication, whether it's AC or DC power.

I did work on one product -- a string monitoring product which was neither power conversion nor power optimization -- which used a proprietary Zigbee mesh, but powerline communication is very old technology. Apparently utilities transmit internetworking traffic on the pilot lines for their own purposes.

You're totally right about PLC being a sensible choice, of course. And yet, this is what their website shows!

Hopefully someone in the marketing department doesn't know how it really works.

 

[tallgirl]

You're totally right about PLC being a sensible choice, of course. And yet, this is what their website shows!
View attachment 2558798
Hopefully someone in the marketing department doesn't know how it really works.

I'd never use a PV product which relied on WiFi to work.

I use as little WiFi at home as possible because I know how it really works ...

 

[ramsy]

Unless the business is no longer around to fulfill the warranty.

Yes, it happened with JLM Energy in 2018, plus installers & contractors go AWAL with peoples money all the time.

Customers are only covered if they got building permits with installing contractor's Additionally-Insured GL certificate, same as any other remodel or construction project.

 

[ramsy]

..having looked at their patent, I'm not convinced the technology is appropriate for high ambient temperature environments. In particular, I'd like to see what temperature profile they've designed for to ensure the "PCM", which they say is a paraffin in the ideal embodiment, returns to the solid phase each day.

Somewhere in that YOTTA link posted earlier, I remember reading the lithium-phosphate chemistry can handle around 113°F max before it shuts down.

 

[ramsy]

So they've sacrificed reliability for installation speed there. Yuck. Enphase made that mistake and it sucks but at least with them it's only a few batteries in each system.

If you are adverse to micro-batteries, you wont like where the R&D money is going.

Take a look at this photovoltaic battery research, which turns solar cells into batteries.

This has been in the R&D stage for years, they're making progress, and it could be viable long before fusion reactors, or room-temperature superconductors.

 

[tallgirl]

Somewhere in that YOTTA link posted earlier, I remember reading the lithium-phosphate chemistry can handle around 113°F max before it shuts down.

The next time you're in Austin in August, go sit under a solar panel around 2-3PM with a thermometer. Dallas and Phoenix are probably worse, but I've never sat on a roof under a solar array in either of those cities.

45C is generally the upper limit for Lithium chemistries. The melting temperature for most paraffins is close to there, but as I mentioned, the battery has to rid itself of enough thermal energy to re-solidify the paraffin before the next day begins.

 

[ramsy]

The next time you're in Austin in August, go sit under a solar panel around 2-3PM with a thermometer..

Roger that, and record breaking temperature extremes occur each year.

Here's a rechargeable 150°C operating Lithium product, but it can't take the cold, below 0°C freezing, and some desert climates can swing below freezing at night to 120°F in the same day.

I've never heard of phase-changing passive thermal, don't know how it works, but since its listed for rooftops those UL 1973 & 9540 standards should have tested it for these environments.

 

[wwhitney]

I've never heard of phase-changing passive thermal, don't know how it works

It's just something with a large plateau in the "temperature vs heat input" curve, because it undergoes a phase change at a particular temperature (or perhaps slightly broader temperature range for something like wax melting).

As a simple example, say you have something that likes to be at 70F, but is exposed to an environment that cycles over the course of a day between 50F and 90F. With enough 70F phase change material in the system, it might stay at 70F all day long. The phase change material will absorb heat (melt) when the ambient temperature is above 70F, and shed heat (freeze) when the ambient temperature is below 70F, and if it never fully freezes or melts, the internal temperature will stay at 70F.

Cheers, Wayne

 

[pv_n00b]

Warranty fulfillment cost nothing for the customer.

You must be kidding, warranties often either don't include the labor to R&R the component or the amount they provide is too little to get the job done. So who pays for the rest, the customer. And that's if the manufacture does not find some way the get out of a warranty replacement. these are rarely, no questions asked, warranties.
I remember one PV module manufacturer that required the customer to send a module to a lab to be flash tested to prove it was underperforming and met the requirements for a warranty replacement before they would replace the module. The cost to do that was more than the replacement cost of the PV module.