Is Electric Central Heating worth it if using Solar Panels?
Passive solar design before you build

On a new build, your very first stop is passive solar design.  Strutting forward and designing a bad old stickhouse, and then bolting on solar as an afterthought, is wasteful.  

Passive solar design means engineering the building so it does not need active heating (except on rare occasion.  The occasion is rare enough that you can get away with cheapie resistive electric heat).  

One way to make passive solar work is to angle the windows and overhangs so the buildings reject sun by summer, but drink up sun by winter... And capture the prevalent temperature (solarization by winter, shade by summer) in the building's rather considerable thermal mass.  This does not happen by default obviously, you have to swerve out of your way to design the building for that. Design time is the time to do this.  

Another method is to make a building partially earth-sheltered, so that by summer, you have an easier time resisting solar heat. Several feet of earth is great insulation and you can't beat the price. Obviously you have to compromise that with having a nice well-windowed home.  

Another design aspect is heat pumps, though with passive solar design they are 99%  of the time in A/C mode.  And ideally you want to interchange with groundwater as your ultimate heat sink.  See, normally, AC/heat pumps are pushing heat "uphill": it's 90 degrees out, and you want your house at 70, so you're dumping the heat in the 90 degree outside air - "pumping uphill".  If your ultimate heat sink is 55 degree ground water, you are "pumping downhill".  It's still pumping, but it's much more efficient.  

Think about what it means for heat-pump (A/C is a type of heat pump) efficiency when the pl, since it is cooler than you want your house to be, and therefore in A/C mode, your heat pump is "pushing heat downhill. Which makes it more efficient.

The overall point is, don't design for inefficiency just because it is conventional, and then try to bolt on efficiency as an afterthought. Really explore the state of the art.  

Another option is a double roof.  It doesn't need to be a contiguous roof; it just needs to put the primary roof in shade.  Solar panels might do that, but firemen are usally kitchy about covering too much of your roof with solar panels.  

Use the grid as a buffer... or not?

How your electricity is billed is a big factor. If you are on net metering, meaning every KWH the solar generates unwinds a KWH off your bill, then you are using the grid as a storage device - you can run a 9pm dryer load using power you generated at noon.  

However if you are paying peak/off-peak charges, or are credited a lower rate for reverse-flow power than forward, then you want solar to operate when you are at energy consumption peaks - in other words when  the A/C is working the hardest. The good news is that A/C requirement is due to solar load, which is exactly what makes solar panels work, so they work in unison.  

The bad news is, in reality, A/C need considerably lags solar load; 3 hours after sunrise my house is chilly, 3 hours before sunset it's unbearable, even though they have exactly the same solarization as far as the panels are concerned.  I suspect that is the house's normal thermal mass at work. That is why one strategy is to greatly increase that thermal mass and insulation, to greatly slow that rate of swing.