Solar/battery quote

cheesesarnie

Hi
Looking for opinions on quote I've had.
15x415w trina vertex s panels
Givenergy 5kw gen3 hybrid inverter
Givenergy AIO 13.5kw battery
£12.7k

Sounds pretty good but installer doesn't think g99 is needed where I think it is?

What do you guys think?
Cheers

Screwdriva

cheesesarnie said:

Sounds pretty good but installer doesn't think g99 is needed where I think it is?

That's a really loud warning sign. I would walk away from them if they do not:

1) Provide MCS G99 + HIES 
2) State in writing that they offer the full 12 year warranty on the All in One
3) Spec a 6kW inverter for the above 6.2kW system (assuming its all a single roof aspect)
4) Swap out the cheap, low end (<£60 a panel) Trina for quality panel brands like Solarwatt/ Hyundai/ Sharp / REC/ Eurener / Qcells/ Panasonic/ Meyer Burger or REA.

An attractive price can often be misused to conceal the above!

cheesesarnie

Thanks. Starting to think the same

Exiled_Tyke

Agree @Screwdriva except that a 5kW inverter could be about right (I read that 80% of peak is optimum for the UK) especially if panels are across two orientations (as you imply)

Screwdriva

Exiled_Tyke said:

Agree @Screwdriva except that a 5kW inverter could be about right (I read that 80% of peak is optimum for the UK) especially if panels are across two orientations (as you imply)

In my relatively humble experience, the best performing rooftop PV installation I've helped with (attached below) has 4.8kW of PV (12 X 400W Sharp panels) and a 5kW SolarEdge Inverter. Despite having only 2 additional panels than us, the site has generated 4.68 mWh year to date (vs our 3.37mWh).

It's no surprise the owner has just asked his installer to cover the area below his dormers with more panels 

I've found that inverter size coming in just under the installed PV capacity is a very safe bet with large, single aspect South facing roofs, especially if a future expansion of the system may be on the cards. On dual aspect roofs, the 80% rule is largely accurate. On triple aspect or higher roofs, I suspect it's even lower - our 7.3 kW tri-aspect installation still retains the 3.68kW SE inverter - we did not "clip" earlier this week, despite the clear, sunny, Indian Summer October days and a 75% increase in daily generation compared to the previous clear sunny day. 

Magnitio

Exiled_Tyke said:

Agree @Screwdriva except that a 5kW inverter could be about right (I read that 80% of peak is optimum for the UK) especially if panels are across two orientations (as you imply)

Agree that a 5kW hybrid inverter is fine. There will be minimal clipping and if it is an issue, the excess can be used to charge the battery.

cheesesarnie

Yes the roof is a bit of a jumble of aspects (after a prior extension). It would have made sense if they'd justified the lack of G99 by explaining that. Instead it was implied g99 was only for commercial installs which clearly is wrong!

Screwdriva

cheesesarnie said:

Yes the roof is a bit of a jumble of aspects (after a prior extension). It would have made sense if they'd justified the lack of G99 by explaining that. Instead it was implied g99 was only for commercial installs which clearly is wrong!

Entirely disingenuous. Run, don't walk, in the opposite direction.

cheesesarnie

Thanks for the advice guys.
Had a further quote through from a supplier who actually understands the need for DNO!
8 x Jinko 435w + Tigo optimisers (across 3 different aspects S/E/W - roof mess)
GE AIO 
£11.4k
or
20 x Jinko + optimisers (12 additional on North facing roof)
GE AIO
£13.2k
Extra £1.8k for 12 panels is tempting even if theyre North facing. Tell me I'm wrong.

Thanks

Netexporter

Extra £1.8k for 12 panels is tempting even if theyre North facing. Tell me I'm wrong.

The sun rises in the NE in summer. A nice early morning/late evening boost. As you have optimisers they should pick up a decent amount of reflected light in the middle part of the day.

Have they supplied the modelling of what you might expect for each layout?

cheesesarnie

Not yet. That comes after a site visit I think (although they have said est generation 2373kw (8 panels at the back of the house) 4899 (12 additional at the front/north). 
Just looking at the google map, the north roof is slightly off north. Not sure if thats a good thing or a bad thing.
Never been a fan of street facing panels before but what can you do?