String Length Query

[TammyTickle]

Hello all,
I'm hoping to gain a little background information (and hopefully confirmation) on the string size best suited to my system, a little more info below:

Three-phase 9kW system comprising 18x 500 JA Solar Deep Blue 3.0 panels as spec'd below:

• Maximum Power Voltage: 38.35V
• Short Circuit Current ISC: 13.93A
• Module Efficiency: 21.1%
• Maximum IMP Output Amps: 13.04A
• Open Circuit Voltage: 45.59V
• Solar Panel Working Voltage: 24V

And a Huawei SUN2000-8KTL-M1 (HC) 8kW Three-Phase Inverter:

• Rated power: 8kW
• Maximum efficiency: 98.6%
• Recommended maximum power: 12,000 Wp
• Maximum input voltage: 1,100 V
• Operating voltage: 140V ~ 980V
• Starting voltage: 200V
• Input Rated Voltage: 600V
• Maximum input current per MPPT: 13.5 A

All panels are on a south-facing roof (181.7 degrees) at the same angle of 27.5 degrees, no shade to worry about as the roof is high and unobstructed.

I was thinking that two strings of 9x panels would be easiest? Would that make sense in terms of the inverter capacity and common best practice?

Thanks in advance for any advice!

TammyTickle

FYI because I know usually of interest: DIY install (EDF quoted 36K euros for the supply and installation of a 9kW system which is madness) The full system including panels, inverter, cabling, connectors, roof mounts and rails is costing 5800euros inc vat and delivery from Spain to France.

[davidcheok]

Paying for solar isn't just costed the raw components. You need to consider permit applications, all the rails, mounts, cabling, grounding cables, clips, combiner boxes, surge arrestor, cable ties, properly sized cables, MCBs, isolators, DB boxes and then the scaffolding, HSE equipment, labour and insurances etc etc etc. Balance of system costs isn't just exactly x components but x+10-20% because of possible defects or breakage while installing etc. Then businesses need to not just make money but factor in warranties (remember they are slaved to you for at least a year). Plus if you intend to have this as grid-tied, you also need to pay a qualified professional to certify the roof structure AND the electrical installations. Once you take into account all this, then make comparisons to the quotes you receive. Only then will you know if its expensive or not. Just some food for thought.