Solar panels to Inverter. Where to run the cables ?

Brian99_2

Thanks for many helpful replies !! Glad this has created a useful discussion.

My inverter will be Sunnyboy1200. These things lose 7% to 9% of the energy as heat.

So another factor: that warmth might as well be in the house.

More wasted energy if it's in the loft (or outside)

My porch is cool (North facing), with fusebox there; I thought, brilliant... ...but my installer says it will "harder to sell the house" with the Red Sunnyboy in the porch.

Comments ?

penrhyn

Yut_Man wrote: »

"cables from panels are low voltage and high current" ????? The panels are wired in series so the voltage from each panel adds up. 500V is quite common. Think you got that wrong way around. It seems to be viewed that the shorter the DC feed gives less loss, where as for AC its not as critical. Im sure a few wiser electricians will elaberate.

Thanks for the info, So do they have some kind of protection for a single panel failure? Need a bit of a tutorial myself.

Freepost

My installation is planned for 22nd November, a 3.825kWp system with an Aurora PVI-3.6-OUTD inverter. Having examined the proposed cable run it looks like the distance will be around 12m. What kind of power loss am I going to suffer with this cable run. The surveyor mentioned that they use 4mm cable, is this sufficient (I know I'm being a bit lazy here, I can't remember the formula and would have to dig out my 'O' level physics book to look it up if nobody's got the quick answer)? The other thing is that on the electrical drawing that the surveyor gave me, it looks like the installation will be divided into two stings and consequently two cable runs to the inverter. I guess two cable runs will reduce the loss, your thoughts will be appreciated.

F

Freepost

Also, what kind of cable is used? I would assume that basic cooker cable would be sufficient! Again your thought would be very welcomed.

F

Brian99_2

I really think the losses in cables really won't make much difference to the overall efficiency, unless the house is enormous.

Biggest loss is the Inverter, 7% to 9% loss, creating warmth which we ought to use !!

Manufacturers should adopt a CHP mentality... where the heat loss is used constructively (warm water etc)

zeupater

Freepost wrote: »

My installation is planned for 22nd November, a 3.825kWp system with an Aurora PVI-3.6-OUTD inverter. Having examined the proposed cable run it looks like the distance will be around 12m. What kind of power loss am I going to suffer with this cable run. The surveyor mentioned that they use 4mm cable, is this sufficient (I know I'm being a bit lazy here, I can't remember the formula and would have to dig out my 'O' level physics book to look it up if nobody's got the quick answer)? The other thing is that on the electrical drawing that the surveyor gave me, it looks like the installation will be divided into two stings and consequently two cable runs to the inverter. I guess two cable runs will reduce the loss, your thoughts will be appreciated.

F

Hi

If you really need to know you could download the SMA SunnyDesign software (http://www.sma.de/en/service/downloads.html) and model the cable runs for your system ... it will give you the cable losses for any cable gauge option that you would want to consider ..... probably makes little difference to what your installer would use though

On DC runs 4mm seems to be standard for a system of that size, with 6mm used on longer runs to reduce resistance and losses ...

HTH
Z

zeupater

Brian99 wrote: »

I really think the losses in cables really won't make much difference to the overall efficiency, unless the house is enormous.

Biggest loss is the Inverter, 7% to 9% loss, creating warmth which we ought to use !!

Manufacturers should adopt a CHP mentality... where the heat loss is used constructively (warm water etc)

Hi

The question which should really be asked is "When will most of this heat be created & will it be welcome/needed when it is ?"

HTH
Z

zeupater

Freepost wrote: »

Also, what kind of cable is used? I would assume that basic cooker cable would be sufficient! Again your thought would be very welcomed.

F

Single core DC pv cables .....

Z

Brian99_2

zeupater wrote: »

Hi

The question which should really be asked is "When will most of this heat be created & will it be welcome/needed when it is ?"

HTH
Z

Very true. We dont need extra Inverter heat in the loft on hot summer days....

Whereas warm water is more useful/usable, especially on cool bright days. Or warmth in a North facing room.

zeupater

Brian99 wrote: »

Very true. We dont need extra Inverter heat in the loft on hot summer days....

Whereas warm water is more useful/usable, especially on cool bright days. Or warmth in a North facing room.

Or more appropriately, using your figures .... pumping an extra 7% to 9% of say 15kWh to 25kWh into the house on a summers day as opposed to 7% to 9% of say 2kWh to 4kWh (if you're lucky) when you need it in the winter ...

Z