What if one has already dozens of photovoltaic solar panels, and just need a good energy storage solution that lasts many years? I trust Tesla more than some others companies that they can deliver it.

You shouldn't. Tesla have a much shorter track record than someone like Iron Edison.

Also… if you read my comment, you'll see the batteries are cheaper than Tesla's… and if you look online, you can see they come in various configurations… rather than predefined 10kWh bricks with 2kW output.

History repeats itself :) Prepare for the 2nd round of Edison vs. Tesla!

You are probably right, and from a quick technical comparison it looks like a much better deal. Definitely not an expert in this field.

At the end of the day Tesla is generating mounds of press, and as a result will probably sell (or in this case reserve) more units.

Am I missing something or are Iron Edison's batteries almost twice as expensive as Tesla's? I'm not adjusting for Tesla's reseller markup.