Can I import PV production estimates from external tools like PV Syst?

Presently, no.

However, you can make SolarNexus reflect nearly the same production values by adjusting the SolarNexus' production estimate using the following process...

Let's assume you created a design in Helioscope and the same design in SolarNexus. For example:

• Helioscope est: 12,500kWh
• SolarNexus est: 12,000kWh
• % difference: 12,500 / 12,000 = 1.0416 (+4.16% difference)

Go to your Services screen, in the PV Output Modeling dialog for your PV system, input 4.16% into the "PV Output Adjustment" field. That will update your SolarNexus estimate to be very close to the Helioscope estimate.