Hang on. There are several authorities that offer "Listing" service. These are UL, ETL, and CSA. All can provide a mark that says the word "Listed", and they are all acceptable in the US and by utility companies. TUV on the other hand can test a product for compliance to UL1741, but to my knowledge, they cannot offer the mark with the word "Listed" unless they are a partner affiliated directly with UL in that laboratory, and that is when you get into issues with the AHJ or the Utility. Some care, some don't and there is a wide misunderstanding about it because it doesn't say "Listed" unless it is the UL mark evaluated by a TUV/UL Laboratory. At least, that's how it was when I was doing it 14 years ago.
The Hoymiles inverters I sell are Listed by CSA, they bear the mark "cUS Listed" and comply with UL1741 and FCC, and they are on the CEC approved list in California. They start at $147 at 350W for a single, $206 for a dual at 700W, or $299 for the Quad at 1500W, or $0.21/Watt AC. A 5kW Sol-Ark is around $5k, or $1/Watt AC, so that's definitely not the starting cost for grid-tied anymore. I can provide a permit plan set with an engineering stamp and a design review is $1079, and where I live, the permit, utility, and NCUC fees add up to less than $300. So that $15k estimate is highly dependent on where you live. My Enphase system with the battery and a ground mount ballasted rack was close to $15k, but if I had known about Hoymiles at the time, it would've been about $7k with the battery. My bad for not doing enough research.