I assume you are getting a third more because you have a third greater surface collection area ie 6kw instead of 4kw and although you have a 4kw inverter its probably rarely at full capacity
So is there any issues with fit payments or any dangers issues with6 kw into 4kw what happens with the extra?
The theory is that with the 6kw array into a 4kw inverter the inverter will be giving out a higher average - it will get to 4kw quicker and then stay there longer because of the bigger array. Not exactly sure what happens to the surplus.
We do get a slighter smaller FIT tariff (13.5p vs 14.9p), but the theory is that the higher yield outweighs the lower tariff. It was necessary to go for 6kw array instead of say a 5kw to offset the reduction.
Our array is split equally East West, at about 10 degrees. We didn't have any room on our southfacing house roof as we already have solar thermal panels on there - but would have needed planning permission for a ground array of 4, or 6, kw and we didn't want to have to go through that planning h*ll (we had a certin amount of 'fun and games' when we dealt with the planners for our house build. Our solar panel installers said put them on the barn roof (which is east west) which is what we did.
It will be interesting to see what effect the low pitch has on the winter numbers.
