3.5KWp Black Phono Solar 250W panels on WSW-facing 40 degree roof with Sunnyboy 4000 inverter and Immersun. Now expanded the system by installing 7 more of the same panels with Sunnyboy 1600 inverter on SSE-facing roof following receipt of permission from the DNO.
I thought long and hard about the Immersun but so far it looks to be a great investment. The gas has been turned off since the array was installed (end of June) and the water is at full heat by mid afternoon. We'll see how it goes when the longer nights arrive but so far I am really chuffed with it and hope that I get at least some pre-heating affect .during the cold part of the year...
Update on the Immersun. As expected the contribution of the Immersun over the winter months was much reduced. I need down to zero on many days but not in proportion to the generation itself. While winter generation in December was only about 13% of July the Immersun contribution was about 20%.
So, overall still really pleased with the investment and now that I have added 50% generation capacity, most of which will be highly effective in the morning it looks as though the returns from the Immersun will also increase.
The one question I didn't ask (as I did not see that anyone else has asked it from the reading I did) and none of those who quoted thought to tell me is what are the benefits or otherwise of splitting an array over two aspects in terms of equalling out the energy production during the day. I have a SSE-facing roof as well as the WSW roof and it could have taken 6 of the 14 panels.
This is in no way a criticism of my installer as I was informed by everyone who quoted about the marginally higher performance of a split array but the installation costs appeared to outweigh the benefits (in terms of FiTs which seem to drive the industry and sales pitch for most firms). However, it would have been useful to know form at least one of them how the daily energy production would be distributed over the day in a split array compared to a single-aspect array.
What I have seen so far (only a couple of weeks at the time of writing) is that I get relatively little generation (well under 1KW) until about midday when the roof comes into direct sunlight and power increases to 2+KW depending on the weather.
If all one is interested in is overall generation figures for FiT purposes this probably doesn't matter but if one is keen to maximise use of the electricity generated then generating on the south-facing roof in the morning might mean that high wattage things like kettle or toaster would presumably be powered by solar, not grid, at breakfast time etc and in the afternoon there would still be enough generated to do the same for cooker or kettle etc, i.e. rather than having a block of generation peaking all afternoon at, say 2.5KW, one would presumably get something like 1.5KW or more spread more evenly over the entire day - or something...
I am sure the software models could provide this information and the impact on it of whatever your shading situation is, so if you are in the same situation as me, be sure to ask when asking for quotes.
The above was a cause of mild irritation as we learned our way into living with solar PV and in the end we decided to install a second plant on that roof. It took a while to get permission from the DNO to exceed the 16amp limit but just about 9 months after the first system went in the second was installed. And having real generation happening before lunch is a real godsend and in my view money well spent.