inverter size for south array and east array and whilst we are at it parallel , series or hybrid wiring

[martygturner]

Hi,

 

Fitting 10x 440w panels, 6 on a south facing wall and 4 on an east wall, roof mount is out just after the war build so timber was riddled with wood worm so don't fancy the extra loading.

 

Both walls have clear unobstructed views of the sun all year at 10+ degrees sun height

 

So what inverter?  3kw, 3.3 or 3.6kw  or something smaller... we are home all day and do not plan for a battery at this time, our main use is 10am - 6pm for computers, washing machine etc we drop down to a telly, fridge and a few lights after that. So its a cut rather than replace the leccy bill, we can suck up all the output during the day and have no plans to export anything.

 

I was planning on a 3.3kw inverter with dual MPPT's wired in a hybrid giving 2 strings of 6 + 4 ... but then have had  bit of a err is that best moment.

 

Basically from March to October there is a window between 2.30-6pm when all the panels will be alive but shifting  the amount of direct light gain, so do I size the inverter for that ie 3.6kw or do I lower the kw as lets face it that will be for some 70 days of the year and go for a lower kw inverter operating at is peak performance witch probably best represents the bulk of the year, and whats best  for wiring up, just good old series, am I over thinking the hybrid wiring option.

 

The inverter will have to go inside the house, there is literally no shade on either wall when the sun hits and cannot be bothered to fit round the back and drag 30m of cable back to the consumer unit and from the panels to the inverter and to be fair our hallway gets a bit chilly so can take a bit of extra warmth.

 

Any advice on wall fixings would be gratefully received...

 

thanks mart.

[-rick-]

Cost/performance difference between those size inverters should be negligable. Get the G.98 maximum, can't see any reason to go lower, but obviously not worth going higher.

 

Look at inverter specs for minimum panel voltage/startup voltage. You are wanting to optimise for low light performance so you want an inverter to be able to operate when the panels are only 10%. Choose wrong here and you might get an inverter that doesn't start producing power until the panels are 25% or more. You also want the string voltages at 100% light to be under but closeish to the maximum mppt voltage for the same reason. So decide how you wire things once you have those specs.