Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. I don’t think there is an active coupon right now – at least in my database.
Link: Banggood product page
Price: -3 USD
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): MVC8SPRING, 8BGwbg2204, pROMo8cuPoN, BG00c906, BG8OFFCOUPON, TTBLACK5, BG589b2e, BGAUGUST8, BGCAPITALOS8, BGCOUPERT8
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for PowMr POW-HVM5.5K-48V 5.5KW 5.5KVA Solar Inverter MPPT 80A is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).