NEC and Building Codes used to have UL and UR requirements (IIRC, UL-Listed was for the final product, like a toaster, and UR-Recognized for components that went in the toaster) written all over in them... About 20 years ago or so, everyone (i.e., laws written, both in US and foreign countries) agreed to change it to NRTL (Nationally Recognized Testing Laboratory). This was allowed to support international trade and give more companies a shot at making money on regulatory listings. Originally, only one lab per country was to be NRTL'ed (UL for US, CSA for Canada, etc.). Later, any number of labs could be approved.

10 years or so ago and earlier, in some cities (like NYC) the annual fire department workplace inspections, it was not unusual to have a coffee pot yanked because it said ETL (another testing company) instead of UL.

In the old days, it was usually UL or no sale to places like NYC (and sometimes a smaller country would accept only UL, if I did not have their local listing lab's sticker). Now-a-days, I can use (and have used), UL (US), ETL (US), CSA (Canada), a couple of German companies to get compliance listing for my computer products for shipping in the US and other countries. Many times, it was just finding a company that could give me the listing in the shortest possible time (UL used to be real slow to get an inspector scheduled and out to see the product).

UL is still the most organized and has the most day to day inspections going on (at least in my area of California).

And, again, I was not trying to cause offense to anyone--I was just trying to explain how it all worked and that it was our law makers that put all of the teeth and legal requirements in the regulatory picture.

For me, as a design engineer (generally for large computer systems), it was just another design requirement. I really did not care one way or the other too much. Sometimes the requirements were stupid and, on occasion, UL made up a "test work a round" for some of the crazy requirements (which did not affect safety) that allowed us to pass--but did not really represent the product as it shipped.

Getting local regulatory approvals (NRTL's) for each country was one of those trade barriers that everyone complains about. If you did not have the correct local mark, your product just sat rusting on the docks/customs. Many times, in the bad old days, it was more just a matter of "greasing the wheels" to get a product into a foreign country. For quite a few years, companies in the US were much better at getting NRTL and CE approvals for shipping into Europe than, for example, a German company was at trying to ship something to the UK because we already learned how to treat Europe (pretty much) as one foreign market.

-Bill

I forgot to mention, more than likely, if it is plugged in, wired in, or somehow otherwise connected to the building's AC wiring (and/or telephone network), NEC and local fire codes are going to require NRTL.

If the outputs of that device (for example a wall-wort battery charger) are low voltage / low current (and SELV--safety extra low voltage--basically a design where it should be virtually impossible for a single failure to cause dangerous currents/voltages from the AC lines to the SELV outputs to occur), then the devices that connect to the SELV outputs would generally not need to be NRTL'ed (such as an IPOD on a charger).

You can probably wave your hands to most inspectors that solar panels are isolated from the building's AC mains, but it is probably easier just to go with the flow. (UL will do tests on the panel wiring, high pot (high voltage barrier tests, inspect the design and come once or twice a year to the production line to ensure that the panels are being manufactured according to their Listing/Recognized requirements--material traceability and safety tests).

-Bill

You folks have pretty tuff inspectors. When I built my house 2 years ago they did not even question where the power was coming from. Just sign the papers with small print offgrid solar scribbled by me.

Really they are not too tough here. I have never heard a word from anyone about it. We had a storm and it broke a small 24 watt panel and the inspector for shelter said he had no idea what it was worth and was the first time he appraised one. So he wrote me a check for 900 bucks for it. I bought 230 watts in panels to replace it with. However I might be one of the only ones in this area who has a solar panel of any kind. I'm guessing it might be the same in your area and they just don't know what to look for or even what they are lookin at.

jon,
he sounds like an insurance representative and one who's not very bright. maybe i should get your insurance and reap a 5x benefit from damaging my pvs. that asside, there's a big difference between an insurance inspector and those that inspect electrical systems for local municipalities and electrical component and product inspectors. though all are supposed to help the public they all do it from different perspectives and shouldn't be confused. had that guy been a jerk, he could've come back on you and told you to eat the loss and require you to prove that the system you are utilizing doesn't pose a threat to the home even if using approved components or not and could thusly raise your premiums or drop you altogether as a result.
municipal inspectors get rediculous at times too with misinterpretations or just being nasty to the point that could counter the efforts that an inspection was supposed to do for safety with at the very least needless increased costs and wasted time(usually benefitting the inspector's finances and/or ego).
this stuff goes on in the component and product area too as they may say to a capacitor manufacturer i'll give you approval if it can be shown to function after being briefly submerged under water. da, it's electrical and shouldn't be used when wet unless it's for that purpose by some stretch of imagination. more hoops are presented for finished products comprised of many components with tests sometimes irrelevant or unneeded for the proper function and safety of the product.