Always use non abrasive cleansers on your solar panels. An abrasive cleaner can scratch the surface of the panel and cause permanent damage and affect how well the solar panel works. There are commercial cleaning solutions to use or you can use a pool skimmer with a very soft cloth on it.
If solar panels are too expensive for you, think about renting them. Leasing is not as expensive as buying, and you can realize your savings sooner, like around a few weeks.
Don’t buy a marginal solar kit off Amazon, watch this video and build your own with better components, balance of system and circuit protection!