A. Need to use ok = simulate() to check if simulation failed.

B. Check for open CSV file before browse().

To replicate A:

1. Create a PVWatts / Commercial case.
2. On the System Design page, choose Specify total system losses and specify a negative total loss.
3. Click Macros and run the Value of RE System macro. Note the runtime exception at line 97.

To replicate B (continuing from A):

4. Change system losses to positive 14%.
5. Run the Value of RE macro twice in a row. Note failed to write to CSV error message.