Solar stand alone heaters

So Ive been thinking about the solar process and this is what I came up with. We have the outdoor lights with their tiny panels, a little battery which stores the energy generated, and the string of lights themselves which do the job of lighting our gardens. Then we have the large solar system which involves panels on the roof, an indoor battery store and the resulting energy for our consumption. Is there something pretty much directly between these two scales? What I had in mind was something like a large/ish solar panel, backed by a battery store, backed by either an actual electrical heater, or socket/s which existing heaters are plugged into? My theory is that you would place these outside on sunny days in the path of the solar energy, then fetch them in early evening when the temperature drops to heat the room you choose. Possibly a few of these to supply warmth on chilly evenings. Is there already such a product? Is this set-up not even feasible due to size/cost/logistics? Would it be possible to make these, the collectors and socket/heater would possibly be do-able, maybe the battery would be an issue due to size/cost. Many thanks!

solar --> electric --> battery --> electric --> heat  is going to be really inefficient. Losses at each stage of the process, and quite a bit of expense.

You'd do better doing direct

solar --> insulated thermal store --> heat.

Fewer losses along the way, less to go wrong.

Solar thermal storage is well understood, but typically done on a reasonably large scale.  Large enough to provide a proportion of the heat to a domestic house is common. The advantage of the larger systems is the solar collector can be some  where with a good solar but the heat itself can be transferred by simply plumbing hot water from the collector to your store. Much easier than manually carrying tubs of hot water in from outside each evening.

https://www.builditsolar.com/Projects/SpaceHeating/SolarShed/Tank/Tank.htm

You may be better with a Trombe wall, oir just carry stones in and out each day and let them heat up during daylight.
Trouble is it works best in summer.
The trombe wall will work in winter.

As Michael says, solar electric is less efficient for heating. Losses in storage conversion are significant. Of course, losses in transmission and conversion inside the house show up as heat, so are not really losses in this use, only making heat in other places than the "heaters".

That said, the best method of solar heating is direct thermal collection and storage, ideally with panels that are connected to the house so losses from their backs go into the house and any losses in transmission and storage are also inside.

Direct solar heating is the way to go. Michael linked to builditsolar, a great resource! Go do a deep dive on the solar heating projects there!
One that might fit your "stand alone" criteria is a "sun grabber", which is a unit that fits into a slightly opened sunny window and hangs down below the sill (not unlike a window A/C unit) it's a passive (thermosyphon) device, although you could power one with a small PV panel and PC cooling fan.

The air, interior, and furnishings of your house become the "storage", and your house might get a bit warmer than you might have set the thermostat for, but the boiler/furnace/heaters won't run at all during the day (you've also turned down the t'stat) and then it takes longer for the heater to get called for heat in the evening.

i know people always talk about solar heating as inefficient. One thing which can be set up is people's solar dump. When it is sunny our batteries are finished charging at like 10am-11am. SO from 11am-4pm we have solar being dumped into our electric water heater.

There are days when i would like to get a radiant heater and put it on for a few hours during the day. Even if all it did was keep the house at the same temp, to me it would be worth it.
Yes maybe inefficient but so is wasting good solar just because it is inefficient.

so just my two cents

If people have solar already installed being wasted why not put it into heating/cooling. Especially if they already have it..

Efficiency is not always an important factor.
Ram pumps in a creek pump a cup of water every 5 secs and maybe has an efficiency of 2%.
IE 250ml of water lifted 60 feet and 10L of water passes through the ram to get that 250mL.
But it works 24/7 as they say and has no input from any other source.
It may actually be 1000% efficient.
At petrol pump in the same location pumping 3000L per hour would be more efficient, but it may drain the creek and needs fuel.

the same applies to solar stuff.
A flat plate water heater is less ' efficient ' than evacuated tubes, but flat plates do break as often in hail, they can be set low so thermosyphoning to a tank can work in which case a 24/7 pump is not needed.
In which case the Flat plate will be a much better choice to make.

I would say overall efficiency is a combination of output vs. expenditure and not just percent of input converted to output. A low technical efficiency can be totally worthwhile if it requires little setup or expense to get started, or uses resources that would otherwise be wasted.