You need to find out how many KW are in your system. This information should be in the sales estimate provided by your salesperson.
After you get this information, you need to compute a cost per KW. If, say, your system has 8 KW, divide the $31,864 by 8, = the cost per KW. In this example, the cost per KW is $3,983.
If you have 8 KW, you have 2 systems--the first is 5 KW, and the second is 3 KW. (Each system is "capped" at 5 KW. You need to file one N342 per "system", meaning you need to file 2 forms. Multiply the first system (5 KW) by the cost per KW, and your number is $19,915.
For the first system, take the $19,915 cost and multiply by 35%, which gives you your tax credit. Here, it is $6,970. However, you are capped at $5,000 credit, so your credit is reduced accordingly.
Same exercise with the remaining 3 KW.
I just did this exercise with my newly installed PV system, where I actually had 4 systems. The Hawaii tax credit system for PVs is unduly complicated. I found a YouTube video (do a Google search) which I found very helpful. It is very elementary, but go through the calculations and you will "get" it.
