Right now the best price with coupon code for 13W Portable Solar Panel Kit 5V is $21.69 (in Banggood). Price history, coupons and price alert are available on this page. You probably want to know what is the best price?
Working voltage: 5V, Product net weight: about 155G/160G/265G, Material: Class A polycrystalline silicon solar panel, Output: Dual USB, Power: 6W/10W.60W
Latest price update (UTC time):
Banggood ($21.69)
Banggood warehouse is located in China. I couldn’t find any coupon for this product on latest product update. Is it cheap? Maybe there’re no more promotions for this item, because current price is higher than average (which is equal $20.63)
Link: Banggood product page
Price: $21.69
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG589b2e, BGd2f208, BGET12, BGET10
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Do you need price history chart (for all/most countries) for 13W Portable Solar Panel Kit 5V? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).