I reckon 25 days is a fair estimate. That breaks down to;

1 day to research sun position, azimuth, etc.

2 days to figure out the various bits of maths involved and write code to do the calculations.

4 days to build a working interactive 3D model.

2 days to build the charts and tables.

5 days for a designer to make a great layout, build assets, etc.

6 days to bring everything together in a website that works across different browsers.

3 days for device testing.

2 days to cover meetings, phone calls, etc.

At a rate of $800/day that's $20,000. I'd add a $5,000 (20%) buffer on to that to cover unexpected scope changes.

$25,000 for what appears to be a single page might sound high, but if the company is getting, say, $500,000 of value from it then it's really cheap. I know of agencies that would charge 10* that if they thought the client could afford it.