Can you do a grid tied system? If so what sort of feed in options are available? I ask because grid tied is easier when running motors.

Terminology - kWh is a measure of electricity used. 1000w for 1 hour, 2000w for 1 hour is 2kWh, 1000w for 2 hours is also 2kWh.

PV is quoted as kWp which is the maximum output that a PV array can produce under ideal conditions.

Heat pumps are quoted in kW which is the maximum output that that heat pump can produce under ideal conditions.

Have you done an estimate of what your proposed PV array (I assume 3-4 kWp) can produce by month. This will give you an idea about how much energy you can produce in the winter when you need the heating.
Look here
https://re.jrc.ec.europa.eu/pvg_tools/en/
Zoom in on the map to your location and fill in the boxes and click 'visualise results' for a chart. The results by months are in a graph and in kWh.

Motors don't like running at either under or over voltage. in addition motors also have a higher start up current. So unless your PV is producing enough power to supply the start up current it wont start. (probably sit there humming and getting hot to the point of tripping the thermal or smoking). So extra controls will be needed to prevent the motor trying to start unless the power conditions are right.
Or
Have a system with a battery where the battery is charged by the PV and the battery (through the inverter) runs the motor (heat pump)
Or
Others may know of alternative solutions.

If you do the sums on setting up the PV system to run a heat pump I wouldn't be surprised if the numbers arn't feasible.

Do you already have the heat pump?
If not I would carry on using the wood stove (I don't like pellet stoves) and use the proposed PV for household power, grid tied or not.

You can use PVGIS to get a pretty good forecast of your likely generation at you location.

I think there's a general view that in winter you typically get 25% of the max summer generation so with a 4kw system you'll get 1kw on a typical winter day. I don't think that would be enough to power a 6kw heat pump??

Use a home storage battery with a hybrid inverter as an interface between the PV and the ASHP. Also link the batteries to cheap rate overnight tariff...easy. As PiH suggested.

Posted By: philedgeI think there's a general view that in winter you typically get 25% of the max summer generation so with a 4kw system you'll get 1kw on a typical winter day.

For my system PVGIS forecast 233 kWh for December and 1010 kWh for July.
The actuals for last year were 275 kWh for December and 1095 kWh for July.
And for 2023 we got 261 kWh for December and 1094 kWh for July-
So for me the actuals were just about spot on 25% for summer max vs. winter minimum.

<blockquote><cite>Posted By: fostertom</cite>If running heating is (one of the) primary aim(s) of your PV, then orient the PVs so as to maximise winter solar capture. That will reduce its summer capture, and will reduce the annual total capture - but often the summer capture is excessive anyway. Maximising winter capture means much more vertical panels (even fixed on elevations not roofs) so as to be perpendicular to solar radiation arriving at lower elevation angles (though no radiation arriving at below 20o elevation is worth having). This assumes you actually receive that low-elevation winter radiation, not shaded by surounding trees/buildings/mountains - if not then you won't capture much winter solar however you orient the panels, so supplying heat pump is a non-starter.</blockquote>

Our average PV generation (14 years worth of data) for the months of November, December and January are 75, 36 and 55 respectively. Our panels are roof mounted at 45 degrees and the sun is so low that the light is partially blocked by my neighbour's trees. They are deciduous trees but I guess the trunks and branches are enough to do the damage.

Is the house off-grid?

Like others said, you need a battery and off-grid inverter to collect together all the bursts of PV during the day, when the weak sun comes between the clouds, and consolidate
them into stable power that keeps the ASHP happy for a couple of hours.

Just to be aware that it will not make very much heat each day, maybe less than a pound/euro, so unlikely to pay back the cost of ASHP and battery. Unless you can use grid electricity the rest of the time?

Modern heatpumps are inverter speed-controlled so startup currents are no longer such a problem, but like all electronics they don't like a stop/start power supply.

The people on the Camelot forum are more electricity focussed than here, and may give you better advice.