I have checked all old coupons and price is 179.99 USD for SP-B150 150W (in Banggood). Just check coupons out (with price alert and history). Let’s see what best price is ATM.
Latest coupon and price update (UTC):
Banggood (179.99 USD)
Banggood warehouse is located in China. Price? Maybe there’re no more promotions for this item, because current price is higher than average (which is equal 114.99 USD) Only one coupon available!
Link: Banggood product page
Price without coupon: 199.99 USD
Coupon (179.99 USD): BGAMMT03
(CouponsFromChina.com tip: you should apply the coupon in your 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): BGiMarsSP150, BG10OFFAFF1, BG622CZ1, BG622eu, BG80622A, BG129862, BG8e685c, BG679ef2, BGd535c2, BG16edd0, BG6ac793, BG3e95aa, BGacea86, BG80622de01, BG80622A02, BG80622ES02, BG80622PT02, BGH80622DE02, BG80622A03, BGchollo150, BG80622B01, BH80622DE03, BGba8a31, BG0f200e, BGc4d3e9, BGd5d4bb, BGH80622DE, BG465bdc, BANGGOODSD, BGacfe4f, BGfd1d45, BG5b2920, BGfdbdb8, BG227153, BG80622g01, 00c906, BGe2bd2d, ADMITAD2212, BG8af58d, 2022ACTIESNL, BGCarEle1, BGc4e703, BGSKUH80622A, BG4c98dc, BG2b8cda, MVC8SPRING, BGd8de7e, BG5baf8e, BG663576, BG635726, BG2ce829, BG19c3fd, BG368475, BGb90f02, BGb3f152, BG98138f, BGe942b4, BGdcbfa8, BG885b73, BG60d391, BGQH150W, BGCarEle4, BG47fbea, BG776440, BGe5b850, BGw23261, BG0566ef, BG3a340b, BG1111so, BGfc467d, BG15951a, BGiMars2022, BGCarEle5, BGd8e584, BGef75c7, BGe9d8ae, BGSCM11, BG845979, BGLMQ15, BGCAR639, BGNEWYEAR8, BGb2568c, BGa9497f, BG0c34bf, BG635686, BG91fc21
(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 – iMars SP-B150 150W 19V Solar Panel [EU] (89.99 USD)
Aliexpress
Click here… to search for iMars SP-B150 150W 19V Solar Panel on Aliexpress
Here are coupons that you can use.
Price history and price alert
Check out price history chart (for all/most countries) for iMars SP-B150 150W 19V Solar Panel.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).