Of about two dozen systems of similar size, with similar facing, in my county or adjacent counties, I'm seeing my performance compared to others as (any shade or superior aspect is noted)
Minus values indicate my system underperforming (although I can't hope to compete with the South-facing systems until summer arrives; I should be about 10% behind them over the last several weeks - all other things being equal)
Systems, SE-facing which I would expect to underperform due to Sanyo panels:
14x235W Sanyo/SB3000HF: -12%
16x250W Sanyo/SB4000TL (slight shading): -10%
16x240W Sanyo/SB2000HF (slight shading): +6%
16x250W Sanyo/Aurora3600OUTD (slight shading): -6%
14x250W Sanyo/SB3000 (South facing): 0%
16x240W Sanyo/SB3800 (slight shading): -6%
MEDIAN: -6%
MEAN: -5%
South-facing systems which I would expect to underperform by about 10% over the last several weeks:
16x250W Emmvee/Fronius IG TL 3.6 (South-facing): +8% (not a typo)
16x245W Sharp/Aurora3600OUTD (South facing): -13%
16x240W REC/SB4000TL (South facing): -6%
14x235W Sharp/SB3000 (South facing): -13%
20x195W HJM/SB3600 (South facing): -13%
MEDIAN: -13%
MEAN: -7%
Other systems, SE-facing, which I ought to be roughly matching:
20x200W Suntech Pluto/SB4000TL-20: -4%
16x250W Siliken/SB4000TL (slight shading): -8%
16x245W Sharp/SB4000TL-20: -11%
16x250W Sharp/SB4000: +12%
17x233W Bisol/SB4000 (slight shading): +28%
MEDIAN: -4%
MEAN: +3%
So is my system a dog performer?
I don't think it is; it shouldn't be expected to keep pace with Sanyo systems (especially not given that Sanyo are vastly more expensive), nor can it compete with South-facing systems at this time of year (especially as I'm between ESE and SE facing, so slightly worse than the nominal SE class which I fall into).