Options for a solar install

Fromdownwest

Hi all,

Looking at the feasibility of an install of 19 panels generating around 7.5kwh. Usage is circa 4.5, with an electric car coming in 2 years.

been quoted

£15,897

• 
  

  440w premium, all-black, bi-facial REA Fusion² panels, exclusive to Heatable

• Plus, a 13.5kWh Tesla Powerwall 3 battery storage system (inc. gateway)

• Hooked up to Tesla's built-in hybrid inverter tech

• Powers your home in the event of a power outage 

• Up-to 3 years 0% APR available

  
  

  Or

  
  

  REA Fusion² + Enphase IQ5P £12,163

  
  
  I am currently on Octopus Tracker December 2023 v1 - last Bill 17.65pkwh
  
  
  Questions
  
  
  Looking at future proofing this setup, and Tesla seems like a solid bet.
  Do the numbers stack up based on selling excess back
• What tariff on octopus would you advise
• 
  
• 
  
• Thank you

Screwdriva

Heatable is an excellent installer and your instinct is spot on - the PW3 + bifacial panels is the way to go. That said, they are priced at the premium end of the installer market and do not paint the invisible roof area behind the panels white (which is key to achieving incremental albedo gains with bifacial panels). Here is a comparable quote seen from an installer I've used several times that may provide useful perspective:

19 X Sharp 435W black Bifacial panels (25/30 year guarantee). 
  1 X Tesla Powerwall 3 with Gateway 
  1 X Bird netting 
  1 X Painting of roof area behind bi-facial panels included (at your discretion) 

£13.1K full installed. G99 included. That's a whopping £2.8K savings. 

I would expect the PW3 to be on Intelligent Flux by the end of the year. 

Reed_Richards

Screwdriva said:

they are priced at the premium end of the installer market and do not paint the invisible roof area behind the panels white (which is key to achieving incremental albedo gains with bifacial panels). 

Wandering off-topic a bit but if I painted an area of my roof white I'm not sure it would stay white all that long.  You would probably want to install panels all the way up to the ridge otherwise rain falling on the unprotected roof above the panels could wash down all sorts of dirt and small debris onto the white-painted area and in a few short years it might end up not nearly so white as it was originally.

Screwdriva

Reed_Richards said:

Wandering off-topic a bit but if I painted an area of my roof white I'm not sure it would stay white all that long.  

You raise a valid and interesting point. Water based roof paints definitely fade but I have found solvent based reflective paints like Chromasol to last several years without any fungal growth/ fading. That said, only real way to be sure is to use a spectrometer. 

Fromdownwest

Screwdriva said:

Heatable is an excellent installer and your instinct is spot on - the PW3 + bifacial panels is the way to go. That said, they are priced at the premium end of the installer market and do not paint the invisible roof area behind the panels white (which is key to achieving incremental albedo gains with bifacial panels). Here is a comparable quote seen from an installer I've used several times that may provide useful perspective:

19 X Sharp 435W black Bifacial panels (25/30 year guarantee). 
  1 X Tesla Powerwall 3 with Gateway 
  1 X Bird netting 
  1 X Painting of roof area behind bi-facial panels included (at your discretion) 

£13.1K full installed. G99 included. That's a whopping £2.8K savings. 

I would expect the PW3 to be on Intelligent Flux by the end of the year. 

Many thanks, I had concerns that the PW3 was overkill based on my usage,but it seems to be the sensible decision in future-proofing the system.

As my wholesale tracker rate is so low, would it make sense to stay on this rate for now?

Screwdriva

Fromdownwest said:

As my wholesale tracker rate is so low, would it make sense to stay on this rate for now?

I would consider a tariff like Go or Intelligent Go or even Agile from October to April, which is when I would switch to Intelligent Flux.