They are avoiding technical details
As is common practice before you have all the relevant patents in place for the new things you invented to use in combination with old technology.
they did not explain the necessity to buy batterries
Nor should they, as extra batteries are not a necessity at all. The base unit comes with 1 battery included and if using it for what it was primarily designed for, i.e. an environmental friendly replacement for a mobile diesel power generator, you don't need more batteries, since you only run it when you run the equipment needing the energy...
When using it in an alternative way, eg as a CHP unit for an on grid domestic home, you have the option of feeding the surplus energy back onto the local power grid and thus again, don't need any extra batteries.
When you do need extra batteries is for OFF grid homes and if you can't or don't want to sell your power back to the grid. Do also note that your "extra batteries" could be your electrical car parked outside your home.
, they did not explained why efficiency is only 20%
For starters, the electric efficiency is 22-30%, and usually at the higher end, not 20. Secondly, this is a sturdy, mobile, low maintenance unit supposed to be durable in a harsh every day professional wear and tear situation, year after year, possibly in far of locations. Thus priority #1 is durability and optimizing both durability and efficiency in a Stirling at a price affordable for regular people sofar has been impossible.
Also, the alternative target market of CHP domestic use will have need also for the heat output, and the combined efficiency is about 90%, which puts it on par with most other modern domestic heating solutions with the extra benefit of 1/3rd of the energy in the expensive high quality form electricity.
and first and foremost, they hid the price.
In the beginning they had prices on the webpage. I presume they later removed them to allow retailers more freedom of setting their own prices as I guess VAT, import taxes, profit margins, local warranty legislations, shipping costs, etc wary a lot across the globe so a price straight from the manufacturer might be more confusing than helpful.
this ECO-fucking-project as fake or worse - cheat. They also sent one troll and then the enemy troll and neither of them were good enough to be missed by my radars.
Well, my radar is good at picking up nonsense from lazy, stupid people that can only manage to hate on the net instead of gathering the information readily available, and you set of all those alarms.
Inresol AB is a stock company, and thus they have publicly available annual reports which gives a lot of info. But yeah, hating is sooo much cooler... *facepalm*
And everyone knows that stirling engine is good only for burning wood.
Considering you have made only 1 single post on this Stirling forum, I guess it's no surprise you are clueless. Stirlings runs on pretty much anything that burns.
So why the hell there are no stirling engines everywhere? Government regulation or some other reason?
It's difficult to design a low maintenance and sturdy Stirling at a price point suitable for regular people and home owners. For governmental, research and military purposes, Stirlings are quite common, but their budgets usually have a few more zeros at the end than average Joe's budget.