Hyundai vs LG vs Sunpower

[SunEagle]

Why are automatic standby generators allowed to run during a power outage, but a grid-tie solar system is not allowed to operate? I'm sure someone could come up with a way to isolate from the POCO just like is done with a standby generator.

My understanding is a big reason that grid-tie inverters can't operate without the POCO is they depend on matching voltage and frequency to the POCO power. Maybe what I read is totally wrong on this.

A standby generator should also have a transfer switch which is required to isolate the power it produces from getting out onto the grid.

Now if the Solar Inverter people had made their equipment that included a way to totally isolate the inverter from the grid yet still work similar to the SMA secure power option yet be able to use all of the pv wattage instead of just 15 to 20amps worth we would not be having this conversation. But consider the extra cost to provide that isolation circuit.

The problem is that all POCO's required a grid tie inverter to shut down if there was an issue on the grid. That was much less expensive to provide then to have a complete fully rated transfer switch and much safer because transfer switches can be defeated which could lead to someone getting electrocuted.

[DrLumen]

Why are automatic standby generators allowed to run during a power outage, but a grid-tie solar system is not allowed to operate? I'm sure someone could come up with a way to isolate from the POCO just like is done with a standby generator.

My understanding is a big reason that grid-tie inverters can't operate without the POCO is they depend on matching voltage and frequency to the POCO power. Maybe what I read is totally wrong on this.

Along with NEOH's post, there is also the issue that in buildings with emergency generators, they have dedicated emergency circuits and a generator to match those possible loads. Batteries aside, I know that system won't work with PV as there would need to be some type of load shedding rules or mechanisms. You may want a HVAC, fridge, TV, some lights and computers to be on your off-grid PV emergency circuits. So, if it is cloudy and the PV inverter can't supply enough power, what should have priority for the power that is available? Not to mention possible damage to appliances not getting the needed power.

[NEOH]

Why are automatic standby generators allowed to run during a power outage, but a grid-tie solar system is not allowed to operate? I'm sure someone could come up with a way to isolate from the POCO just like is done with a standby generator.

My understanding is a big reason that grid-tie inverters can't operate without the POCO is they depend on matching voltage and frequency to the POCO power. Maybe what I read is totally wrong on this.

Because Stand-By Generators ...
a) are not ever tied into the grid
b) are isolated via an auto or manual transfer switch
c) are a Voltage Source, they create the own Voltage and their own Frequency
d) may operate over a wide range of voltage and frequency

Because Grid-Tie Inverters ...
a) are tied into the grid via a circuit breaker
b) typically do not have a transfer switch
c) are Current Sources that FOLLOW the Grid Voltage and the Grid Frequency
d) operate within a very narrow voltage & frequency, required for auto shutdown with grid shutdown or out-of-range

Some (newer) Grid-Tie Inverters do provide an Off-Grid AC Power Outlet without a battery bank!

But if you want STABLE off-grid electricity from a PV Array then you need a hybrid system with a battery bank ( ie clouds )

[ButchDeal]

Why are automatic standby generators allowed to run during a power outage, but a grid-tie solar system is not allowed to operate? I'm sure someone could come up with a way to isolate from the POCO just like is done with a standby generator.

My understanding is a big reason that grid-tie inverters can't operate without the POCO is they depend on matching voltage and frequency to the POCO power. Maybe what I read is totally wrong on this.

Who sais they can not? Mine does every time all the time.
the reason that most grid tie systems shut down is that that is all they are capable of doing. To operate without the grid you need a more expensive bimodal inverter system.

[reader2580]

A lot of stuff in the NEC is pushed by equipment manufacturers because they profit off the sale of the more expensive gear required to meet the new codes. I bet manufacturers make more profit from an AFCI breaker than they make in total revenue from a regular breaker.

[reader2580]

I will continue with another question, is it worth the inconvenience to a homeowner to not get power from their PV system if the grid goes down due to a grid tie inverter shutting down to protect a POCO worker from getting electrocuted?

Why are automatic standby generators allowed to run during a power outage, but a grid-tie solar system is not allowed to operate? I'm sure someone could come up with a way to isolate from the POCO just like is done with a standby generator.

My understanding is a big reason that grid-tie inverters can't operate without the POCO is they depend on matching voltage and frequency to the POCO power. Maybe what I read is totally wrong on this.

[SunEagle]

I would have to think that any RSS proposals are born from requests/concerns from first responders and linemen rather than some marketing think tank for increased profits. Having dealt with many gov't agencies I have found that the reason may be obscure and the applicable situation improbable but there is a reason.

Not unlike an HOA telling people what paint colors to use on their doors.

Here is an article mentioning the concerns of fire fighters for roof mounted solar pv systems.

[J.P.M.]

I would have to think that any RSS proposals are born from requests/concerns from first responders and linemen rather than some marketing think tank for increased profits. Having dealt with many gov't agencies I have found that the reason may be obscure and the applicable situation improbable but there is a reason.

Not unlike an HOA telling people what paint colors to use on their doors.

As I wrote, seems to me lots of things start with good intentions. It's the leaches who see those attempts at good intentions that turn them into what often wind up as bureaucratic profit centers. RSS seems a good idea in principle. The reality may be that there are other ways to accomplish the same ends, but once established, the status quo (RSS ??) is hard to un-entrench or modify except to add more bureaucracy. Happens all the time.

[DrLumen]

I'd respectfully suggest that the reality may be a little less dichotomous that they will or will not always respond in the same way.

It also seems, from what you reference, and no real surprise to me that the probability exists that firefighters, like electricians and others assume a circuit is always energized, and that personnel protection systems will fail and protect themselves first.

I, perhaps more than most, am about completely cynical that most things peddled and crammed down people's throats like RSS, while well intentioned, quickly turn into profit centers for leaches. But I've also got faith that human nature, particularly the preservation part of it, will be more inclined, however slight, to act when there is at least a potential path to greater personnel safety made possible by the presence of an RSS.

Maybe any first responders reading this thread would care to offer an opinion more informed than mine.

I would have to think that any RSS proposals are born from requests/concerns from first responders and linemen rather than some marketing think tank for increased profits. Having dealt with many gov't agencies I have found that the reason may be obscure and the applicable situation improbable but there is a reason.

Not unlike an HOA telling people what paint colors to use on their doors.

[J.P.M.]

Firefighter surveys, for one. There are a few independently published sources that pretty much agree. If you can find any evidence that a firefighter would in fact respond differently, I'd love to see it.

From this study:

I'd respectfully suggest that the reality may be a little less dichotomous that they will or will not always respond in the same way.

It also seems, from what you reference, and no real surprise to me that the probability exists that firefighters, like electricians and others assume a circuit is always energized, and that personnel protection systems will fail and protect themselves first.

I, perhaps more than most, am about completely cynical that most things peddled and crammed down people's throats like RSS, while well intentioned, quickly turn into profit centers for leaches. But I've also got faith that human nature, particularly the preservation part of it, will be more inclined, however slight, to act when there is at least a potential path to greater personnel safety made possible by the presence of an RSS.

Maybe any first responders reading this thread would care to offer an opinion more informed than mine.

[inspron]

....but referral whores can make ~ $500/successful referral ....

Whoaaa. I have been screwed missing out on the referral fees.. hahahah

The 2nd system I purchased was actually higher cost per watt than the first.

[sensij]

I'd like to know how you gleaned what seems to be the certain knowledge that homes with/without RSS will not be treated differently by firefighters.

Firefighter surveys, for one. There are a few independently published sources that pretty much agree. If you can find any evidence that a firefighter would in fact respond differently, I'd love to see it.

From this study:

Respondents expressed the desire for rapid shutdown functions to work under damaged conditions, but none expected that they would. All would treat damaged arrays as energized. (All were made aware that the standard being developed for the evaluation of rapid shutdown components will not address fire or heat damage.) Some respondents expressed the desire for comprehensive positive indication that the rapid- shutdown function operated as intended. For internal array controls, an example was light indicators in the array or some similar visual method. Most however were accepting of some higher level indication that did not provide complete assurance.

[J.P.M.]

Almost totally off-topic for this thread, but since it involves LG panels, I'll use that as an excuse to post it..

No more off topic perhaps than your post of a 2015 price. I was merely offering a comment as to another possible reason why prices seem to have dropped, and may continue to do so from the $4.00/Watt you saw to what the OP found recently. If that's off topic, hang me up. Just use the same nail holes as the last person used. Saves time.

[max2k]

So the question I ask, is RSS worth the trouble and cost to everyone just to save the life of one First Responder?

I will continue with another question, is it worth the inconvenience to a homeowner to not get power from their PV system if the grid goes down due to a grid tie inverter shutting down to protect a POCO worker from getting electrocuted?

Simple answer for me is Yes to both questions.

My point was different- RSS at array level already provides enough protection for ungrounded array- ff can cut through the whole thing holding his chainsaw with bare hands without any danger of being electrocuted provided they turned off AC disconnect and activated RSS. This was / is even up to code in 2014 NEC.

POCO worker just needs to turn off AC disconnect to make it safe for them to work on the line side of things. I don't see how RSS could make this any safer.

[J.P.M.]

Based on human nature, probability, common sense, and the actual response of firefighters given these scenarios, there is no difference in how homes with and without RSS will be treated. Even "plainly labeled" RSS requires more thought than anyone responding to an emergency is likely to put into it. Some versions of RSS require manual operation, some operate automatically. Some will drop only conductor voltage outside of a 10 ft perimeter around the array, some will drop conductor voltage 1 ft outside, and some will drop conductor voltage inside the array. Will a firefighter scour the labeling to try to guess which code cycle of RSS was used on the installation? Will a firefighter trust that rooftop RSS electrical equipment melting in the middle of a fire is performing as intended, or will they just assume the system is live and proceed assuming the worst case?

I'd like to know how you gleaned what seems to be the certain knowledge that homes with/without RSS will not be treated differently by firefighters.

I'd also suggest that emergencies are precisely the time when thought and care are required. Clear thinking and deliberate actions in emergencies are characteristics I thought I've observed in professionals.

I was and am under the impression that rapid shutdown requirements were mostly or entirely about the safety of first responders. I'm ignorant of most of the particulars of the issues that led to the NEC 690.12. But, I'm under the perhaps erroneous assumption that labeling and signage requirements of NEC 690.12 are something that most firefighters and other first responders have been trained to recognize. If so, and I may be (incorrectly) projecting what I'd do in the situation, but if there are 2 homes burning, both of which have PV systems, mine and the guy next door to me, and his PV is new enough to be NEC raid shutdown compliant while mine is not, I'm only suggesting that if resources, including time, are limited, and all other things being equal, which seems at least possible and IMO, likely, the RSS equipped system will have a higher probability of being seen as a more tractable situation and will see efforts first. I'm not questioning professionalism, but being of the opinion that firefighters have more common sense and self preservation instincts than most, not to mention situational awareness, it just seems like the most efficient use of resources and higher personnel safety that the RSS equipped system will see efforts first.