As noted in the comments for issue AR-1442, the "Download CSV" function, "the CSV rows are all the rows for all the records involved. It's kind of just a dump out of solr. It would be another feature to constrain the rows."

This makes the CSV download essentially unusable for large datasets. I'm not entirely clear on what is going on, but when I download the CSV for a result set of 174 accessions, I get the following error from Excel when I try to open the file:

The file contains more than 1,048,576 rows or 16,384 columns. To fix this problem, open the source file in a text editor such as Microsoft Word. Save the source file as several smaller files that conform to this row and column limit, and then open the smaller files in Microsoft Excel. If the source data cannot be opened in a text editor, try importing the data into Microsoft Access, and then exporting subsets of the data from Access to Excel.

Clearly some thought needs to go into what fields are included in the CSV download, rather than dumping everything from Solr.