Can anyone help me to understand ?

[budwozza]

Hi Guys,

Had a PV system installed last week, 16 x 250w Sanyo panels wired as 2 strings of 8 on the roof - then connected in parallel in the loft and ran as a single input into the inverter (SMA SB4000TL) - apparently it is more efficient that way.

Can someone explain to me (in simple terms please) how it is more efficient to have a single input (1 x 7.2A and 1 x 376V - best case senario if panels working at max output according to Sunny design) over 2 seperate inputs (2 x 7.2A and 2 x 376V)

I cant get my head around how having 2 strings connected in parallel is better (or more efficient) than 2 seperate strings.

Also another question I have is that since having my PV system installed, my EON enery monitor thingy, has gone a bit crazy and doesnt seem to know whats going on (I think it counts some of or all of the generated electricity as used power), is there anyway to make it work correctly.

Thanks

Wozza.

 

[Worcester]

Your E-on thingy isn;t able to measure direction, so it doesn't know of you are consuming or generating.

With regard to two seperate strings or two in //el, the 4000TL will take either option.

If the striings, are indentical in orientation, inclination, make, type, size of panel, shading, then it should be just fine sharing one mpp tracker

 

[Worcester]

Try Here:
Connecting energy monitors with Solar PV
and:
PV and wireless energy monitors - conformation required
and:
energy meters

Hope that helps - on one of those threads is a schematic I did which shows the problem.

 

[BruceB]

And another link. Your installer would need to arrange it so your eon device was only measuring consumed power rather than a mixture of consumed and generated. There are some diagrams in this Wattson installation manual that show how to do it:
http://www.diykyoto.com/store/assets/0000/0619/WATTSON_RENEWABLES_Eng_v0.5_low_res.pdf
You want the arrangement on page 8.
Regards
Bruce