Considering this solar instalation is a for-profit venture in cloudy UK and will reduce carbon output without subsidies, I'm calling it a win whether it powers 1000 houses or 350,000.
91,000 homes would be about 91,000 * 3,000 kWh / year = 273 TWh / year. You need an average of 31 MW over a year to produce this, which roughly tracks 350 MW with ~10% capacity factor. So over a year this seems to be correct.
On a day to day basis however the project only includes 700 MWh of storage. That's about 24h of the electricity consumption of 91,000 homes. A single cloudy winter day and those batteries are empty. So if you look at shorter time periods than a full year there's a huge variation in how many households can actually be reliably powered by such an installation. It's likely somewhere between 1,000 (several days of cloudy winter) and 350,000 homes (sunny summer).
> It's likely somewhere between 1,000 (several days of cloudy winter)
How do you figure? Solar technology is moving so rapidly you can't even look at the efficiency of the panels from a few years ago to do the math. Is the 1,000 number a guess or did you do the math for the 900,000 some panels they will have at that site?
"This is a project that will generate up to 350MW of clean renewable electricity to power over 91,000 homes"
https://www.clevehillsolar.com/