Aliexpress
Here are coupons that you can use.
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – KROAK K-SP03 100W 18.15V Shingled Solar Panel [EU] (-3 USD)
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (118.99 USD): BGLMQ15
Coupon (123.19 USD): BGSCM11
(CouponsFromChina.com tip: coupon code has to be applied in shop’s cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BG8f1196, Cuponation9, BG056efe, BG109999, BG109899, BGCarEle4, BG5cc0ce, BG091506, BG3c3608, BG0d058f, BGCarEle5, BGe50f4f, BG845979, BG37328d, BGCAR639, BG162e7c, BG5e24ac, BG3b5821, BG3caf49
(you can check these old coupons out, but these probably won’t work)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – KROAK K-SP03 100W 18.15V Shingled Solar Panel [EU] (-3 USD)
Price history and price alert
Price history (for all/most countries) for KROAK K-SP03 100W 18.15V Shingled Solar Panel is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).