Position Of Micro Inverters

[dominator99]

Hi All

I've been running a 16 panel 3.92kW PV system for over 3 years on an SMA string inverter (2 strings).

I initially planned the system using Enecsys micro inverters but because of the imminent change to FIT's rules (large reduction in the FIT rate) I installed the above string system instead.

The DC cables of my array don't connect together on the outside of the roof but inside the acttic space, as the original intention was to fit the micro inverters inside the attic to allow for easy access/replacement.  At the time, Enecsys could see now reason not to fit their micro inverters inside the roof space as long as the DC 'tails' from each PV panel didn't exceed 3 metres (no they didn't really explain why; I can only assume it was an issue with resistance over a longer run of DC cable).

I'm now looking at switching to Enphase M215 micro inverters for my 16 245W PV panels & would appreciate any comments on my proposal

 

[binky]

why waste your money, you already have a very efficient inverter, unless you have shading issues don't bother, microinverters are basically only worth the cost if shading is a major issue. Even then if you download the software update from SMA they will proably have included the upgrade to 'global opti-tracking' which has shade compensation built in. NB the photon test of solaredge which is very similar to micro-inverters made test comparisons against a grade B inverter, you have grade A. If you are still feeling despaerate to do this Solaredge do make a conversion module to work with a normal inverter.

Had forgotten about the dc cables into attic trick - brill way of avoiding the issues of when microinvertes fail

 

[dominator99]

Thanks for the input.

I do have a potential shading issue looming due to a large & growing tree due south of my panel. This is a council owned tree I've petitioned for prunning or felling but I'm still waiting on a decision.

At the moment the shading only occurs across the autumn to spring period when the sun is low in the sky

I only intend to switch to micro inverters when my current SMA string inverter fails & needs a replacement (I've got 18 months left on the 5 year warranty).

Checking online, the best micro inverters appear to be Enphase. Emailed them yesterday about fitting their micro inverters in the attic & they could see no problem with that.

When enquired about DC cable length from PV panel to inverter they suggested keeping the runs as short as possible to minimise volt drop along cable.

I suppose I could use larger guage DC cable to minimise the volt drop from PV panel to micro inverter

Can't fault Enphase customer service, which is more than I can say for Enecsys!! - no wonder Enecsys went bust in the UK.  They gave me the 'run around' back in 2011 when I was thinking of using their product; I'm glad I didn't in the end when you think of all those customers of theirs now stuck with useless 20 year warranties