HOMER Knowledge Base
Incentives for Storage Systems in HOMER Grid
Product: HOMER Grid 1.1.1
The engine calculates the fraction of battery energy that came from renewable sources after the simulation is completed. It uses that fraction to calculate the ITC and MACRS incentives.
The engine calculates the fraction of battery energy that came from renewable sources after the simulation is completed. It uses that fraction to calculate the ITC and MACRS incentives.
-If you have below 75% of the charging energy from renewables, you get 7-year MACRS and no ITC
-If you have above 75% of the charging energy come from renewables, you get 5-year MACRS and a portion of the ITC*
-If you have 100% of battery charging energy come from renewables, you get 5-year MACRS and the full 30% ITC
* It works like this: if you have 80% charging energy from PV, you'd get 30% * 80% = 24% ITC credit. HOMER Grid does this calculation -- there's no approximation or anything, it's done as defined for the incentive. Here is the NREL guide on federal storage incentives: https://www.nrel.gov/docs/fy18osti/70384.pdf
In many cases, with a large PV array, a large fraction of the charging energy does come from renewables.