UK question on winter PV output

[Shimmy]

Is it economic to increase our array?! Or should we put a log stove in?!

You shouldn't put in a log stove; it is a great solution when it gets too cold for the air source heat pump to work efficiently (~ -10-20C), but it is a waste with a more mild climate.

Going with a 10kW array and the 5kW inverter would give you about 30% more annual energy for about 30% higher cost (assuming there is enough space on the roof). So, the economics are about on-par with your base condition.

 

[solarsimon]

Add all the solar you possibly can would generally be the advice of most existing UK solar owners.
On cloudy UK days you won't come close to powering your heating. In coldest weather with clear skies it'll work well, but the days are short.
Woodburner - it depends on the cost of logs in your area.

 

[fega72]

Wow! Thank you all for your replies, I should have mentioned in my brief that we are connected to the grid, so we won’t freeze. The issue for us is the trade off between what is economic to install versus savings and income from energy export ( which will be very small!).
To give you a flavour of our energy costs in the UK to presently pay £0.28 per kw/hr and was due to go up to close to 0.45 but the govt have intervened and capped it at 0.28, to stave off the pain but at some point it will have to be paid for. The most generous of feed in tariffs pays £.075 per kWh a healthy profit for them.
We live in Norfolk, East Anglia the driest part of the uk and we rarely get snow and our winters are fairly mild. I hear what you say on what we can expect over winter which is disappointing but is it economic to increase our array?! Or should we put a log stove in?!

Having a back up plan to heat your house is a good idea. Not enough solar power combined with grid failure / shut down by the "brilliant" rolling black out government plan will let you without heating this winter.

 

[OffGridForGood]

In such mild winter weather you may find a pellet stove easier to control than a wood stove, and although it needs power to run, unlike a heat pump it is not a lot of energy. I use a Pellet furnace to heat a 3,000sqft (290sqm) workshop in far colder climate using my off grid solar to power it. I have found a problem with a wood stove can be overheating a building in mild weather, and being tied to it since it can't feed itself.