Line loss/resistance over distance

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Posted by Bhikkhu Samahita on December 15, 2006, 06:40:41 AM

Re: Line loss/resistance over distance (Reply #5)

Dear friend Ken:

One can go higher than 48 volt with
serial coupling of 3-5 panels...
They will have Open Circuit voltages of 80-90V
Shorted functioning circuit voltage somewhat lower.
(Usually number of panels x ~16V)
Therefore is the Kaneka thin-film (Voc=90V!)
so attractive. At these higher voltages the
current and line loss drops drastically!

Outback MX60 charge controller takes Voc max 150V
Solar Converters PT 90-30 charge controller takes Voc max 180V
Please redo the calculation at these higher voltages & lower currents and you will see for yourself!
Still battery voltage can be kept at 12 or 24V
Then maximum power tracking (MPPT) boost will be good!
That is: On cold days one will gain ~30% increase in charge
current.
Only in the power cable Panel-2-controller will be
high voltage. Controller-2-battery will still be nominal ~12V or 24V or 48V!

« Last Edit: December 15, 2006, 06:43:44 AM by Bhikkhu Samahita »

Posted by Jeff Butera on December 15, 2006, 11:25:47 PM

Re: Line loss/resistance over distance (Reply #6)

Quote from: James Cormican on December 13, 2006, 12:10:57 PM

more details, what modules do you have? what is your battery bank voltage and inverter? where are you located geographically (for temperature deration)?

- james - Alt-E staff

James - this is a proposed system in Western MA. I really want to install PV spring 2007 but have a couple of concerns to address. First, we may not stay in our house due to jobs, so I'm seriously looking to install a system I could reasonably move with me to another house. While my roof pitch/orientation are near perfect for this (MA) location, my roof is extremely high (almost 45'). Since I will be installing much of this myself and I want the possibility of easily relocating, a ground mount system is far more appealing at this time. I have open, unobstructed space on my lot so I can optimize orientation and adjust angle through season easily with ground mount.

I'm looking to install somewhere between 2 and 3 Kw, ground mounted on my lot about 150' from house, so I'm allowing 200' including running wiring through basement to interverter to be located near main panel.

I'm on grid and because of both startup costs and proximity of inverter to gas water heater and furnance in basement, I'm not installing a battery bank at this time (yes, I know there are safe H2 venting solutions). Thus I'm looking for some panels, inteverter, meter/cutoff mains and associated wiring .

I'm open to thoughts/insights.

Posted by Tom Mayrand on December 27, 2006, 02:51:30 PM

Re: Line loss/resistance over distance (Reply #7)

« Last Edit: December 27, 2006, 02:55:23 PM by Tom Mayrand »

Posted by Tom Mayrand on December 27, 2006, 02:54:03 PM

Re: Line loss/resistance over distance (Reply #8)

Jeff, why not move your inverter outside, at your array. Then run cheaper 120V romex to your AC panel.

Posted by Tom Serra on January 24, 2007, 06:56:12 PM

Re: Line loss/resistance over distance (Reply #9)

I agree with tom. Keeping your DC system components close is smart design. It will save you cost on heavy DC wiring and potential voltage loss. AC voltage loss is much less of a concern. Many exterior rated grid-tie inverters are available.

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