I have had solar hot water since before RHI and am generally happy with it. I recommend oversized collectors if possible and and oversized water cylinder. Between them these allow plenty of prewarmed water on cooler days and storage of hot water on hot days to contribute to requirements on a following cooler day.
You can’t store domestic hot water for long but depending on your circumstances you might get some benefit for up to three days from one really hot and sunny one.
The disadvantages of solar are the need for occasional service (mine needed a new pump after 8 years) and that once the water is as hot as you dare they have no additional function, whereas PV may be relatively inefficient but you can export excess.
On the subject of “as hot as you dare” you ought to have a safety mixer to reduce the flow temperature. As well as being safer, by reducing deltaT you also reduce pipe losses.