Green Energy

Would it not be nice to have an inverter (2kw) which is off the grid that can work by having a very small buffer (1 kwh) to power applications that can work intermittent. So when the sun goes away, the applications (such as a pump or fan) work for one hour more and then stops. Like a UPS.

I work for a company that uses small solar pumps for small holder farmers and these pumps do not have batteries. So when the sun is away, the pump simply stops working and continues to operate when the sun is back.

I would like something like that for my shed. My question is this, does anyone knows the correct terminology for such an inverter and or do you know a brand as an example that can do this?