Refurb - Extension and MVHR and Solar PV - What when?

[Tetrarch]

The long term plan is for all three.

 

The project is a 1914 essentially Detached house with a large outbuilding. Not DIY but the builder is happy for me to contribute

 

 

 

The extension is a 28m single storey extension, flat roof. The build will necessitate the removal of the entire rear wall of the house and then replacement with a steel beam over 8m span and a new timber-frame wall above. The roof will be replaced as part of the project. Work is scheduled to start in March 24

 

MVHR - getting MVHR into the flat roof structure might be problematic so it may be limited to a single extract in the kitchen and all the other MVHR pipework being within the original house

 

Solar - The outbuilding has a 10m x 3m almost perfect South-facing pent roof with a 15-degree pitch so I'm looking at a quite a substantial array here

 

My question is ordering. The Solar PV is almost a stand-alone install. I will be running some more permanent electrical cabling. The only issue is that the electrical grid connection is on the North side of the house.

 

I assume that the MVHR would likely be an easier install whilst the roof is off, but it could be done before if it makes sense

 

Any opinions or experiences welcome

 

Regards

 

Tet

 

 

[joth]

Just to clarify, the MVHR is in the main building, not the outbuilding? If so, yes these are two completely independent projects so by large it's just confusing to wrap them up in a single question. (aside from financing constraints, but you don't mention that at all).

 

For the Solar, as you say main limit is getting the supply cable in from the meter head. Dig the trench with duct for this when you're doing other ground works, for the extension founds maybe? Is the outbuilding already there? If it's having a new roof, then do the solar as part of that project, going integrated panels should save on roofing tiles. You may be better running DC cable to the meter head and placing the inverter there. Depends if you may want to add batteries (dc coupled hybrid inverter) and where you have space for that.

 

MVHR main thing is to get it in before making good work is done. The duct work can always be installed incrementally rather than in one big hit. Just be sure to keep ends of pipes sealed to stop dust etc getting into them during the works.

Presumably you're aiming to improve airtightness around the existing property, and achieve a good level on the new extension? To get best benefit or the MVHR people generally cite <3ACH as a goal.