by pass diodes

[steptoe]

never had any use for these in the past,

if I had doubts about shading I installed different panels,

but, done an install last year where the panels had to be put in a different location on site, I'll post some pix,

anyway, 2 strings of 8, one of the strings had to have split panels, 4 +4, 4 of these panels are now set back slightly more than the other 4 and are getting some shading,

any ideas about what diodes I need and how to fit them?

inverter is aurora power one, requiring 120v minimum at max power [worst case scenario],

panels are Sanyo HIT250E @ 34.9v, so Im assuming that taking 4 from 8 is still giving me >120v, TBH, I think only 3 panels are really affected, but Id like to do the whole 4.

 

[steptoe]

OH, OK, like I said, usually I sort out different panels for jobs like this, but they were spec'd by the customer, and when we got to site she had decided she wanted one of the floor mounted banks moved back slightly, it was explained it would now be in shade but she wanted to try it anyway.

Im fairly certain the pics are already here somewhere, job I done in the Lakes,

I'll search for it in a mo.

 

[Jono Pashley]

May be complete nonesence but would the bypass diodes in the panels not already be performing that function and further additions may be of no benefit? But what do i know we always went the easy route and used Solar Edge with optimisers.

 

[binky]

you posted pictures previously. Panels do have diodes built into JB on rear. Those designed for shading issues tend to have more diodes. You only need 3 panels working to reach voltage required by inverter, so perhaps you are worrying too much?

 

[steptoe]

Would the shaded panels not pull the others down?

The install has come in about 1000 under predictions, I didnt think that was bad considering one of the banks want ideally placed.

 

[Jono Pashley]

The inbuilt diodes should prevent them pulling it down too much, no revised prediction based on new positions?

 

[steptoe]

The inbuilt diodes should prevent them pulling it down too much, no revised prediction based on new positions?

obviously not,

I didnt do the predictions.

:C

TBH, I thought the original predictions were optimistic anyway,

---------- Post Auto-Merged at 17:56 ---------- Previous post was made at 17:55 ----------

you posted pictures previously. Panels do have diodes built into JB on rear. Those designed for shading issues tend to have more diodes. You only need 3 panels working to reach voltage required by inverter, so perhaps you are worrying too much?

I thought it was OK, it was the customer that was wanting more, dont they always?

 

[OnOff]

A bit here seemingly SPECIFIC to these Sanyo panels intimating that they're "odd":

Inverter choice

 

[binky]

Nothing odd about Sanyos other than the higher output voltages. Assuming prediction wasn't madly optimistic, then failure to peform would indicate an issue. But then we are talking baout the Lake District, which is a bit famous for raining and low cloud, which might explain a few thing.

My own system gets shading from a few objects at different times of the day, can't say I've ever really noticed whole string dragged down by one panel, and Power One inverter will run down as low as 9W

 

[steptoe]

its 4 panels binky, 50% of the string.

dont Sanyos have the thing where they are segregated on the length rather than the width, from what I can glean.

 

[binky]

its 4 panels binky, 50% of the string.dont Sanyos have the thing where they are segregated on the length rather than the width, from what I can glean.

4 panels should be enough to get things moving, but have just read brochure - start up voltage is adjustable down to 120V.

Other option is to re-string the panels into 2 sets of 4 (having double checked all the parameetrs first of course as I don't have PV sol with me - I would call Power One )one of the trackers has 2 inputs. This way half the string should work absolutely fine with boost from affected panels as shading is removed.