SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) € in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2016 USD ($) shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) shares	Jun. 30, 2016 USD ($) shares	Dec. 31, 2017 EUR (€)
Financial statements in U.S. dollars
Accumulated other comprehensive income (loss) related to foreign currency translation adjustments, net	$ (207)	$ 132	$ (178)
Basic and Diluted Net Earnings Per Share
Total weighted average number of shares related to the outstanding stock options, convertible preferred stock and warrants to purchase convertible preferred stock, excluded from the calculation of diluted net earnings (loss) per share due to their anti-dilutive effect | shares	374,156		197,516	16,208
Severance pay
Severance expenses	$ 1,131	4,331	$ 2,995	$ 1,761
Shipping and handling costs
Shipping and handling costs	8,131	$ 45,821	29,693	$ 21,922
Warranty obligations
Minimum term of warranty obligations for inverters		12 years
Minimum term of warranty obligations for power optimizers		25 years
Maximum extended product warranty period		25 years
Derivative financial instruments
Derivative instruments	5,098
Derivative assets	19		221
Derivative liability			$ 401
Lease assets		32,000
Lease liabilities		$ 34,000
Euro Member Countries, Euro [Member]
Derivative financial instruments
Derivative instruments | €					€ 54,000