4kw system with only 8 panels?

Spies

My roof only has enough area for 8 panels, I don't want to go for a 2kw system as it doesn't seem as worthwhile, have panel capacities (density?) increased at all to the point where I can get somewhere near 4kw (3.6 would be fine!)

Are there installers which would facilitate this?

Reed_Richards

So you want panels capable of 450 W to 500 W output.but the standard size (about 2 m x 1 m per panel)?

Spies

Reed_Richards said:

So you want panels capable of 450 W to 500 W output.but the standard size (about 2 m x 1 m per panel)?

They can be a little larger than that if needs be, 2.2 x 1.1 would still fit 4 across I think.

Reed_Richards

Ther would seem to be a few available like: https://www.itstechnologies.shop/products/495w-mono-half-cell-black-frame-solar-panel?variant=32107338203234&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=EAIaIQobChMIsa75yuDB8QIVAWHmCh1i8QmTEAQYASABEgLqD_D_BwE

Hexane

350W and 365W panels are now commonplace and 400W panels are affordable. The 495W panels Reed_Richards linked to don't seem wildly expensive either. 8 x 400W would give you 3.2kWp which is well worth having.

Spies

Are there any pitfalls with the larger density panels? I would have 4 on a SSE roof and 4 on a WSW roof.

What size inverter should they be specifying? 

Screwdriva

I faced similar space issues on my roof. Your best option is the newest crop of LG Bifacial panels. These are officially rated at 415W each, but if you paint the roof behind them in a solar reflective white paint, this will rise anywhere from 5-15% over the official rating.

Realistically, you can expect ~450W peak per panel on clear sunny days.  You will also outperform conventional panels on overcast days.

QrizB

Spies said:

My roof only has enough area for 8 panels, I don't want to go for a 2kw system as it doesn't seem as worthwhile, have panel capacities (density?) increased at all to the point where I can get somewhere near 4kw (3.6 would be fine!)

Looking at Bimble Solar's comparison page it seems the 495W JA Solar panels might fit your size and power requirements, and are competitively priced on a pence-per-watt basis.

The 540W Canadian Solar ones might also work (they're a bit taller).

If those are both too wide the 410W JA Solar bifacials are under 1.1m wide and half the price of Screwdriva's (lovely, I'm sure) LG ones.

Spies

So it turns our 12 will actually fit fine, at least the installer thinks so!

I thought 5x3.6 might have been a bit tight for 8 panels. 

Hexane

Spies said:

So it turns our 12 will actually fit fine, at least the installer thinks so!

I thought 5x3.6 might have been a bit tight for 8 panels. 

do be cautious of getting too close to the edge of the roof....

"Roof mounted solar arrays that are too close to the ridge or the verges (side edges) of the roof will be subjected to excessive wind loading, which can result in catastrophic damage to the roof. Designers of on-roof systems should not propose arrays that are too close to the edges of the roof, or they should choose an alternative mounting system that mitigates the effect of wind uplift."  (according to Red Electrical)

Spies

He did say about leaving a 30cm border around the panels so I think he knows what he's doing.