Bob,
That's very interesting curve. Guessing for most home users its more cost effective to purchase more cells for increased power than paying more for higher efficiency.
I really don't recall what I paid for remote radio site solar power about 15 years ago. I believe they were 30 to 50w panels and cost about $400. Our first panels were made by Arco and Solar Electric (something) made the last ones we installed.
This was commercial mountain-top comm sites only reachable by helicopter about one month/year due to weather. Our largest site was shared with State of Alaska who maintained a mw link from Kenai Peninsula to Kodiak Island (about 70 mi over water). We had five radios, most of which were 5w but two had 30w amps (all FM). Originally we used a battery bank rated at 10,800 AH at 13.2v (were air cells) which had to be replaced every three years. But we installed a two panel solar charged system using two 100 AH deep-cycle batteries to supplement the fixed battery bank during roughly 6-months of high sunlight in the arctic summer.
We thought that would extend the main battery bank life to four years but it did not quite do it. Energy use analysis was complicated by multiple users so our guess fell short.
Helicopter cost each year for one trip to the mountain ran $5,000 for 40min flight one-way and standby time on the mountain while we worked (usually four hours). After being stuck on the mountain for seven days in 40F-40mph winds in rain we decided to keep the helo on the mountain so we could get off quickly in event of bad wx which could develop in 15-min socking in the mountain top for long duration. Winter had the shelter covered over under 15-20 foot of snow with winds upward of 200 mph. Top of the mountain had year-round snow cover.
Nice to be retired <smile>
73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: dubususa@gmail.com