> I've now lowered my budget to $4000 for the same setup I was planning to spend $6000 on two years ago, and with 400W panels, I no longer need to upgrade to a larger RV to begin the project.

Keep in mind - the dollar is down ~10-15% in that time frame, so in real terms, the previous cost might have been >$6600 in today's dollars vs ~$4000 or a >40% reduction.

The cost of electricity is up ~5.5% compared to last year: https://www.bls.gov/regions/midwest/data/averageenergyprices...