@newhouse87 as much as you can fit south facing. Then west. But your installer should recommend orientation to maximise output

@newhouse87 South facing as much as you have space for would provide maximum production with the rest on west facing. If your finances would run to it, give serious consideration to installing battery storage which would allow for greater flexibility in terms of maximising use of solar energy to power your ASHP. Regards, Toodles.

@newhouse87  As @toodles suggests, it depends on whether you intend to install a battery and your split between home use and export.  I have recently had 8 panels fitted on an (almost) easterly-facing roof and 6 on an (almost) southerly roof. Per panel, the energy output is slightly higher for those on the southerly roof but there is some shading from the early evening from trees to the west. In your situation, thinking only of roof placement and not where the energy goes, I think I would do as your installer suggests and fit 12 & 6. You will then have a single roof area remaining in case you wish to expand in future (I have bits of roof of various sizes for this purpose). As a result of my battery (13.5kWh) I have paid only standing charges since my equipment was installed.

By the way, that chimney is a nuisance.

Thanks for replies. The chimney wont interfere too much with the west panels as far as i can see. I wont opt for battery yet as prices coming down and i can sell any excess to grid for decent price at the moment. We used most electric during highest tariffs of 5-7 with cooking so west facing suits this. Did my theory of placing 6 west panels on small roof over sliding door rather then all 12 on big west roof make any sense, thinking that farthest reaches of west roof will get sun last and in winter might get v little. I could try get panels on small roof behind heat pump south facing but was worried about other roofs shading it and also told bigger strings of panels better rather then putting say 3-4 on small roof.

Your installer’s suggestion of 12+6 is the best suggestion. You can always add more blocks (with its own optimiser) later.

Aas a bungalow you avoid the bigger upfront and modifying costs of scaffolding so you can make changes fairly easily. 
Batteries are coming down in price but you are missing out on the savings while waiting. There are threads on here about making good savings self building batteries if you want to make savings.

 Latest installer suggested

I could get 5 on south roof in pic2 and 4 south roof pic1 behind heatpump and 9 on west roof but  Do people think the small south roofs for the 9 panels would be suitable, not losing light due to other angles on the roofs?

Greetings from Greece. 
8kwp installed capacity comprised of 14x565wp Luxor Solar panels. 7 of them are facing southeast and 7 northwest (due to roof area constraints). Sungrow inverter SH8RT and Sungrow battery 9.6kwh. Commissioned in September 2024. The 2025 yield was 9Mwh. 
PV sizing was done with the intention to install an ASHP, which is currently taking place (Midea 16kw, R290 based model). The PV annually produced energy available for the ASHP is circa 6.5Mwh expected to decline as PV panels age with time).

Kalosórisma @mk4. Thanks for sharing.

One of my objectives this year is to see how heating requirements vary across Europe, is I'm glad you've posted here. In your case, the 16kW heat pump is quite a hefty unit. I assume it's a water-based heating system (rads and/or UFH). I would have assumed that countries around the Med would make use of more A2A set ups to help with hot summers. 

@editor You are right in both observations. 
16kw is a hefty unit, but installers here are weary of proposing smaller units in houses like ours (detached, 240sqm, 20 radiators with 3 units per single pipe loop) mainly because of the radiator networks and also because most people try to use the ASHP as an oil burner (high temperatures and on/off operation). One of the reasons we chose midea is that it can be downgraded to 14 or 12kw.

Indeed almost everybody here uses A2A units for cooling and occasionally for heating, the heavy usage is cooling though.There is a government campaign for replacing oil burners with heat pumps, so ASHP are getting some traction. We live in a cool athenian suburb (400m elevation) and are getting along without any air-condition unit (just plain fans, everything shut during the day and open windows at night).

So, I'm off-grid here in Finland. I have around 14kW of solar installed at the moment, and will be adding another 5kw of vertical solar panels this year. The battery at this time is 120kWh, but I will likely get to 200kWh by the end of the year. It was designed this way: add more capacity over time as prices get lower. All of it was designed and installed myself: the panels are on ground mounts (no roof install), the batteries (LFP) are made from large prismatic cells (3.2V and around 300Ah each). 

In winter when there is not sun (I'm at 63 degrees north), panels don't really generate anything. So during those months, I run a generator (on bio diesel which I make myself) to charge the batteries once or twice a month. 

Heating is a combination of a heat pump in the shoulder seasons (I'll start using it again in about to weeks), a wood gasification boiler and a masonry fireplace. Wood comes from my own forest, and is processed with electrical tools (chainsaw, splitter) in spring and autumn. I'm converting an old tree farm to a natural forest, so lots of monoculture needs to be removed which will provide me with firewood for the rest of my life and then some.

I have the details of every system including heating systems, solar, water, etc. documented here if you're interested.

@upnorthandpersonal 

Greetings from 38 degrees south! Seems to me you are ready for the Apokalypse…! 😀 

Posted by: @mk4

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Seems to me you are ready for the Apokalypse…! 😀 

Or as we call it here, Tuesday 😉