New Solar PV Installation

scorp_a

Hello solar PV experts  & enthusiasts,
  I am planning to put a PV system on my house. I  know I am a bit late into this game but its better now than never!
My home is in Bristol. I have a fairly decent roof. Available space on roof is 10 X 3.4 meters,  35 degrees pitched, south facing with no shading at all. Pretty ideal for  PV installation.
I have an electric car that can take around 55KW when fully charged. 
Household monthly usage would be around 500-600KW  with car charging.  
The system in my mind is this. 
- 7 to 7.5KW PV array (20-22 nos of 350W panels)
-  8K ( or 6?)  Solix inverter
- Iboost for water heating
-Bird protection kit 
Questions
1) Is this system looks reasonably good? 
2) Do I need to add  battery?  My theory for not adding battery now is that I can use the car battery to use spare elec in the day time as the car will be at home mostly till the end of next year. I could add a battery next year -  hopefully prices come down too. 
3) Do I need optimized panels (solar edge)? Note the roof is perfect and no shading at all! 
4) What price points should I expect for this system with decent panels (like Longi or JA etc - Not the super expensive ones)

Expecting some valuable insights. 

Martyn1981

Hiya, and welcome. Great post, sounds like you've got all the basics (and much more) of PV.
System as you describe sounds fine, I think you make fair points about a battery, so you can come back to that in the future.
For a straight forward unshaded roof I don't think you need worry about Solaredge. Both my systems are Solaredge, and I would recommend them if needed.
Inverter sizing for 7-7.5kWp, I think 6kW+ will do you well. Your system (orientation and pitch) is going to peak high in the summer, and if you were nearer the coast with some extra cooling, then perhaps 7kW inverter might be argued, but 6-7kW will be fine, and you can see what the installer suggests.
I think you might find 370Wp panels are now typically available.
Price wise, including the extras you suggest, I think less than £1k per kWp should be a starting point as the system sounds simple, unless there are any particular scaffolding issues.
Have fun!

scorp_a

Thanks Martyn. 
The main reason for opting a 8KW Inverter is car charger that needs 7KW. I know the system cannot provide  7KW even during peak and with concurrent houshold usage, it still needs to take current from the grid.

Martyn1981

scorp_a said:

Thanks Martyn. 
The main reason for opting a 8KW Inverter is car charger that needs 7KW. I know the system cannot provide  7KW even during peak and with concurrent houshold usage, it still needs to take current from the grid.

I'm with you. No, don't worry, a 7-7.5kWp system will hardly ever generate over 7kW. At peak the panels will get hot (fast) and that will impact efficiency, expect about 80% sustained in the summer, less on still hot days, so around 6kW sustained, though you will get some great peak spikes, maybe over 100% in Apr & Oct when the sky is clear and cold, but these won't last long.

Just a suggestion, but you may find that granny charging the cars, when generation is above 2kW is a great way to drive on sunshine, at least most of Mch to Oct for you (Apr to Sept for me as I don't have S facing panels). Then on brief occasions when generation is really high, use the fast charger with hopefully only a minor contribution from the grid.

scorp_a

Yes granny charging make sense. Thanks for the tip. 

scorp_a

Got two quotes so far. 
1) 7.45KW -  £8600 - Big nationwide energy provider
2) 7KW - £6750 - Regional installer
Waiting for couple of more quotes. 

scorp_a

scorp_a said:

Got two quotes so far. 
1) 7.45KW -  £8600 - Big nationwide energy provider
2) 7KW - £6750 - Regional installer
Waiting for couple of more quotes. 

3 ) 7.36 solar PV system (16 x JA460W panels) - £7,900 - Regional installer. 

All quotes including bird guard + iboost buddy. 

Coastalwatch

scorp_a said:

Yes granny charging make sense. Thanks for the tip. 

Yes indeed. Or, you could get a Zappi(or similar) charger installed which monitors panel output and directs it into the EV! But of course it's another investment although there may still be a government grant available to assist with it's purchase or installation. Can't remember which.

Solarchaser

I'd agree with all thats been posted.
Car is a better battery than home batteries for soaking up the extra.
6kw inverter should be good.
Granny charger or zappi for charging car using solar.

Cheapest quote is best imo

Exiled_Tyke

Sounds a good set up.  My thoughts to add: 

1. Yes definitely no battery - the car will take any surplus. 
2. Yes - don't need Solar Edge
3. Definitely agree with Martyn - a smaller inverter should serve you far better as more efficient at lower output levels and you won't get near the top end (7kW) much at all. It may save a few quid to reduce the spec too.  I have 3.3kW of panels going through a 3kW inverter and I can count on one hand the number of occasions I've hit 3kW.  I reckon the ideal for me would be about a 2.7kW inverter. 
4. Suggest you name the installers - some on here may know of them. 
5. No harm in getting another quote? 

scorp_a

Thanks all for the comments. Very useful!
I got another quote for 6.3KW system  for £6300. Current quotes,
1) 7.45KW -  £8600 - Big nationwide energy provider
2) 7KW - £6750 - Regional installer
3) 7.36KW  PV system (16 x JA460W panels) - £7,900 - Regional installer. 
4) 6.3KW  PV system (18 LONGI 350 panels + sofar 6KW inverter) - £6300- Regional installer. 
All including iboost and bird  guards.