• COUNT()
• DIFF()
• LASTCHANGE()
• MAX() *
• MD()
• MIN()
• ROUND()
• SUM()
• SUMACTIVE()
• TOTAL()
• VALUE()

Standard operators can be used in all formulas, such as +, -, *, /, ( and ).

This would add the two Watt values of two inverters together and convert to kWh:

VALUE('delta0w_ac') / 1000 + VALUE('delta1w_ac') / 1000