Comparing solar proposals

greenbee

I've had two solar surveys and proposals/quotes from two local companies - and having read through some threads here am thinking that I might need to try to get more!

There's a significant difference between the proposals - not least that one proposes 23 x Jinko 440W panels, and the other 14 Trina 415W (I see both brands are seen as low-end by a number of posters!). The 23-panel proposal includes a Teslsa Powerwall battery and both a Tesla and a Growatt inverter (I see the latter is another potential red flag). The 14 panel proposal includes a myenergi Libbie inverter and battery. 

I have some questions to go back with anyway, as I've asked for an in-roof systems (birds, squirrels etc) and I'm not clear that they have both taken this on board. 

We haven't been in the house for long, so don't know what our energy usage is likely to be, but we work from home and also have a very small oil tank for the size of the house. Towel rails and one radiator are electric, there are 60-odd LED downlighters, and we plan to put electric UFH into bathrooms (we have 2 wet UFH zones already as well as two radiator zones) as well as eventually putting in ASHP for at least the wet UFH (radiators and pipework being replaced this year are also being done with lower flow temps in mind) and possibly putting in a swimming pool with ASHP. So while at the moment our electricity demand isn't huge, we envisage it increasing (new cars are likely to be a plug-in EVs too).

We have a LOT of south facing roof on the house and garage, with minimal shading, so it seems sensible to take advantage of this. And also to get it done before we do too much else to the rest of the house! 

The proposals also include EPS (so we can keep working from home and not have to drive 2 hours into an office every time there is a powercut), and a microdiverter (while it may not be the most economical option, anything to reduce the dependence on oil and need for constant top-ups of the tiny tank is worth it from our perspective).

I'm obviously concerned about the feedback on the Jinko and Trina panels, and need to understand why the Trina proposal has so few panels given the space. Is there anything else we should be considering? 

Screwdriva

Would you mind sharing the quoted prices for both systems? (It sounds like they have ignored the request for in roof system so I’ll assume it’s on roof for now)

For your perspective, the system specified below should cost no more than ~£17.5K installed with a ~£1K premium for an in roof installation using the same panels. 

23 X 425w Sharp panel system (25/30 year guarantee) + 
23 X SolarEdge optimizers (25 year warranty) +
  1 X SolarEdge 10 kW inverter (20 year warranty) +
  1 X Tesla Powerwall 2 w/ EPS

I don't recommend Trina, Jinko or Growatt regardless of cost, and would always recommend optimizers are fitted with in-roof installations (see below for images where shading impacted an inroof + flat roof install)

I'd consider the MixEnergy iHP cylinder instead of a diverter. A more efficient way to heat hot does not exist (yet) 




 

greenbee

I forgot to set an alert for this, and then work got in the way so I forgot to check! Thanks for the feedback.

I'm working with the electricians who are doing the rest of the work on the house - mostly because it's easier, I've seen their installations and know their customers are happy. Plus there won't be any arguments about it being someone else's fault when problems arise! 

As bats have been found in the main roof, for now we're installing an in-roof array on the garage roof, getting the inverter and battery sorted out, and then leaving the main roof until the bat people say we can work in there (and doing all the other stuff that needs doing in the main roof at the same time - tidying up the wiring, replacing ancient extractor fans, removing old birds' nests, topping up insulation etc and replacing the loft hatch with a less draughty one.

The hot water tank isn't currently scheduled for replacement, so for now a diverter looks like the best option, but I'll bear that in mind for when it does need replacing. I'm working on a slow schedule of upgrading the heating (radiators and pipework) as each room is refurbished so that I can move the heating over to a heat pump - two lots of underfloor heating could go immediately, but I'm not quite ready to make the leap yet (particularly as my next door neighbours have commented how noisy the heat pump on the other side of them is - the issue with living somewhere quiet is that any additional noise is noticeable!).