John you know I would always say just max out your solar, don't stop at what you need, grab more if you have the real estate and the funds to do it, put in enough solar coverage with lithium backup, to drive a 2.4kW electrolyser 24hrs, feeding your secondary / winter backup from stored hydrogen, for those days when there is not enough sun to keep your lithium stored up, and overall you will be permanently off-grid, energy independent, but not only that, you will have excess hydrogen to sell at market rates.

If you can't stretch to that yet, I would still say to aspire to that, and do whatever you can towards that, so in any question of whether or not to carry on using diesel, or go to solar, of course I would say go solar, dump the diesel before you are forced to. When diesel or fossil fuels fail, as they have to, its likely to happen so suddenly, the prices going negative, and staying negative, it will catch everone off-guard, even folk that thought they were prepared for it. The bottom will fall out of that market with no resistance, when the switch to solar hydrogen finally happens for real.

On waste of solar on the heat for your home, I would not worry about that, your net use of energy would still be positive, just because you are dumping some into hydrogen, you could never dissipate more heat than the raw solar energy on the planet would, if it was not driving your system. Your net effect on global temperature would have to be to be assisting push the temperature back down.

Your net activity would be creation, rather than destruction, as it is for most of us, until we too can make that switch.

The heat pump then wouldn't make much difference either way, you would still be net temperature reduction, no matter how much you throw to heat in your radiators.