Anyone know why these units are cheap

[fakdaddy]

Says a 40a 400w to 600w

600 Watt Solar Panel Kit, with Charge Controller(40A) 2pcs 300 Watt Flexible Monocrystalline Solar Panel kit Photovoltaic Module for 12-24V Battery Charging Car Battery Camper RV Yacht Battery

https://a.co/d/gm19Eif

Can always return if not up to spec .... but seems cheap ?

 

[sunshine_eggo]

Because they are junk and falsely advertising.

 

[robbob2112]

LIES!!!!

The best NASA can get are just above 25% conversion - they pay an astronomical amount of money for those.

 

[sunshine_eggo]

Note the panel size. You get 200W/sq-meter typical.

1.065 * .27 = .28755 sq-m

.28755 * 200W = 57W

2*57W = 114W TOTAL for the two panels.

What they're doing is using the cheap, shitty PWM controller's maximum theoretical output as "600W"

40A * 15V = 600W

 

[fakdaddy]

thx all - figured

 

[robbob2112]

If you are just looking for a few panels my wife is finding them daily on FB marketplace. Also, there are lots of spare panels when people do the DIY, upgrade, etc.

If you are doing a whole house sized solar setup then santan solar sells panels by the pallet or as little asgroups of 6 if you need them shipped.

 

[Bop]

I love the 'weasel words'- note they say UP TO 30%, not 30%...
So even if they were only 10%- thats still 'up to 30%'...
;-)

 

[Supervstech]

LIES!!!!

The best NASA can get are just above 25% conversion - they pay an astronomical amount of money for those.

View attachment 217436

Well, NASA in fact has around 45% efficient... however, they are in space well above most of the atmosphere, and they are incredibly, INCREDIBLY expensive panels...

 

[sunshine_eggo]

Well, NASA in fact has around 45% efficient... however, they are in space well above most of the atmosphere, and they are incredibly, INCREDIBLY expensive panels...

What you linked is not a typical solar cell. They require concentrated light of a MUCH higher intensity than STC or in space.

NASA uses gallium arsenide cells that peak at about 39%, but their $/W is a wee bit high.