All example numbers are invented for illustration, not market prices. "In base" is the part of an adder already paid for by the base price per watt, for example the string inverter an adder replaces. Cost is your own cost for the line, as a total. Per-unit adders use rate times quantity. Fixed adders ignore quantity. Percent adders ignore quantity. Entries accept 12,500 or 0,15; a value such as 1.000 is ambiguous and is rejected, so write 1 or 1000.