Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 02, 2022	Jan. 03, 2021	Dec. 29, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 1,323,493	$ 1,124,829	$ 1,092,226
Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	1,121,203	843,382	735,737
Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	191,465	254,735	243,282
Others
Disaggregation of Revenue [Line Items]
Revenue	10,825	26,712	113,207
Solar power systems sales and EPC services
Disaggregation of Revenue [Line Items]
Revenue	975,045	792,190	713,506
Solar power systems sales and EPC services | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	786,707	540,690	409,859
Solar power systems sales and EPC services | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	180,494	245,391	231,281
Solar power systems sales and EPC services | Others
Disaggregation of Revenue [Line Items]
Revenue	7,844	6,109	72,366
Component/product sales
Disaggregation of Revenue [Line Items]
Revenue	240,911	185,858	185,620
Component/product sales | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	240,911	185,858	185,620
Component/product sales | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0	0
Component/product sales | Others
Disaggregation of Revenue [Line Items]
Revenue	0	0	0
Light commercial products
Disaggregation of Revenue [Line Items]
Revenue	72,126	97,136	112,398
Light commercial products | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	72,126	97,136	112,398
Light commercial products | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0	0
Light commercial products | Others
Disaggregation of Revenue [Line Items]
Revenue	0	0	0
Operations and maintenance
Disaggregation of Revenue [Line Items]
Revenue	13,952	28,639	51,626
Operations and maintenance | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	0	0	0
Operations and maintenance | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	10,971	8,036	10,785
Operations and maintenance | Others
Disaggregation of Revenue [Line Items]
Revenue	2,981	20,603	40,841
Leasing revenue
Disaggregation of Revenue [Line Items]
Revenue	21,459	21,006	29,076
Leasing revenue | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	21,459	19,698	27,860
Leasing revenue | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	1,308	1,216
Leasing revenue | Others
Disaggregation of Revenue [Line Items]
Revenue	$ 0	$ 0	$ 0