Note 6 – Inventory

As of March 31, 2017 and December 31, 2016, our inventory consisted of the following (in thousands):

	March 31,		December 31,
	2017		2016
Raw materials	$	693,499	$	680,339
Work in process		254,684		233,746
Finished goods		1,141,556		1,016,731
Service parts		130,597		136,638
Total	$	2,220,336	$	2,067,454

Finished goods inventory included vehicles in transit to fulfill customer orders, new vehicles available for immediate sale at our retail and service center locations, pre-owned Tesla vehicles and energy storage products.

For solar energy systems, leased and to be leased, we commence transferring component parts from inventory to construction in progress, a component of solar energy systems, leased and to be leased, once a lease contract with a customer has been executed and installation has been initiated. Additional costs incurred on the leased systems, including labor and overhead, are recorded within construction in progress.

We write-down inventory for any excess or obsolete inventories or when we believe that the net realizable value of inventories is less than the carrying value. During the three months ended March 31, 2017 and 2016, we recorded write-downs of $21.0 million and $12.7 million, respectively, in cost of revenues.