Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2021	Jun. 28, 2020	Jul. 04, 2021	Jun. 28, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 308,927	$ 217,667	$ 615,325	$ 508,213
Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	254,119	160,306	492,057	387,053
Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	48,176	50,319	114,438	100,931
Others
Disaggregation of Revenue [Line Items]
Revenue	6,632	7,042	8,830	20,229
Solar power systems sales and EPC services
Disaggregation of Revenue [Line Items]
Revenue	300,016	203,011	597,372	473,230
Solar power systems sales and EPC services | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	248,600	155,372	481,377	377,286
Solar power systems sales and EPC services | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	46,038	47,858	109,030	95,485
Solar power systems sales and EPC services | Others
Disaggregation of Revenue [Line Items]
Revenue	5,378	(219)	6,965	459
Operations and maintenance
Disaggregation of Revenue [Line Items]
Revenue	3,392	9,397	7,273	24,467
Operations and maintenance | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Operations and maintenance | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	2,138	2,136	5,408	4,697
Operations and maintenance | Others
Disaggregation of Revenue [Line Items]
Revenue	1,254	7,261	1,865	19,770
Residential leasing
Disaggregation of Revenue [Line Items]
Revenue	1,354	1,329	2,474	2,653
Residential leasing | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	1,354	1,329	2,474	2,653
Residential leasing | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Residential leasing | Others
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Solar services
Disaggregation of Revenue [Line Items]
Revenue	4,165	3,930	8,206	7,863
Solar services | Residential, Light Commercial
Disaggregation of Revenue [Line Items]
Revenue	4,165	3,605	8,206	7,114
Solar services | Commercial and Industrial Solutions
Disaggregation of Revenue [Line Items]
Revenue	0	325	0	749
Solar services | Others
Disaggregation of Revenue [Line Items]
Revenue	$ 0	$ 0	$ 0	$ 0