Product: HOMER Pro and HOMER Grid

Users often wonder why HOMER provides two different places to enter a component's size: first in the cost table, then in the 'sizes to consider' table. This looks like duplication and it can strike new users as confusing, but in fact this separation can be helpful if you know how to take advantage of it.

Each component input window in HOMER contains a Costs table on the left, and a Search Space table on the right, in which you tell HOMER what sizes to actually model. 

But the cost table lets us enter more complicated inputs if we wish to do so. In the example below, we have changed the cost table so that the first kW of PV costs $10,000, the second costs $8000, and any additional PV costs $5000/kW. In addition to a quantity discount, this could reflect economies of scale in shipping or installation. 

The two tables give us flexibility. We can enter as much or as little cost information as we wish, regardless of how many sizes we wish to consider. More importantly, we can change or add to the sizes to consider without having to change the cost data. That means you can concentrate on finding the best size of each component, one of the main functions of HOMER, without having to keep entering cost data for every size you want to consider.