12volts or 24 volts setup?

[petset77]

12 or 24v setup

everything i have read explains in detail why 24vdc is more efficient than 12vdc. unless you will be wiring part of your structure for direct 12v DC usage, (12v lighting, RV based small appliances, power supplies etc., are less expensive than 24 or 48vdc versions), then 24v is better. even then, the cost for extra household wiring/circuit protection will offset much of the cost. price out the difference between #6 and #1awg wire. huge. AC to DC breakers, huge. if many of your loads will be DC, your runs will be over 10 feet unless you're in a tiny RV. if all of your loads will be 120 or 240vac, the under 10' number for the DC side cable runs might be realistic. as, or more importanty, if you already have your inverter in hand, that will determine how you wire your array and batteries. DC voltage will be posted on the unit somewhere, and in the paperwork. it will also post the maximum DC current draw, and wiring size for that is available in chart form in many books and online. finally, you might decide to upsize your system in the future. eventually, a 12vdc system will not cut it. i would wire it correctly now. good luck with your project.

[raymondalmeda]

Mike / Sunking,

In a totally different topic. With my current equiptment, (3pcs. 12v 100w panels and 2pcs. 12v 100AH AGM Batteries). What can you recommend for my system to achieve best efficiency? I mean, would my panels be enough to charge my batteries? My plan is to have my computer, which consume 600wats in total, be powered as much as possible by solar setup. We have deviced an inverted online UPS (will get power from the batteries but load gets cut @ 12.2v, then it's immediately transfered to the GRID) to be used in this application.


Thanks!

[dinablaster]

i am not good at this calculation but i learn that in school, P have bigger lost in 12 wires than same P in 240 wires and much smaller in 240 (50-60Hz)

Your load demands factor heavily in the voltage decision. If you never have over 1,000w of load (including motor starting surge) then 12V would work. If you go above 1,000W -2,000w, then a 24V system is better, less amps at the batteries needed. Above 2,000w, consider a 48V system

You looks like a specialist on this

[Sunking]

At 12 volt input you will need a 125 amp fuse and a minimum 1 AWG copper conductor.
At 24 volt you need a 60 amp fuse, and a minimum #6 AWG copper conductor.

[Mike90250]

Voltage Drop Calculator :

http://www.nooutage.com/vdrop.htm

http://www.electrician2.com/vd_calculator.htm

http://www.elec-toolbox.com/calculators/voltdrop.htm

[raymondalmeda]

What is the VA rating of the Inverter? 100 watts, 2000 watts, what?

IF your inverter does not specify the minimum size wire and breaker needed on the battery input, you need to find another manufacture.

The Inverter is rated @ 1KVA, power factor of 87% so maximum continuous rating is 870watts, surge rating is 1600watts.

Thanks!

[Sunking]

Unfortunately, the inverter did not specify the required wire sizes. That's why I was hoping on finding answers in this forum.

What is the VA rating of the Inverter? 100 watts, 2000 watts, what?

IF your inverter does not specify the minimum size wire and breaker needed on the battery input, you need to find another manufacture.

[raymondalmeda]

The minimum size wire will be listed with the inverter instructions.

Unfortunately, the inverter did not specify the required wire sizes. That's why I was hoping on finding answers in this forum.

Thanks!

[raymondalmeda]

I've still got no idea what your loads (on the AC side of the inverter) are.
120V or 240V inverter?

240v mike! Total computed loads would be 500 - 600 watts for 4 hourds per day.

[Sunking]

The minimum size wire will be listed with the inverter instructions.

[Mike90250]

I've still got no idea what your loads (on the AC side of the inverter) are.
120V or 240V inverter?

[raymondalmeda]

Yes, a 24V system has more leeway with voltage loss, and cable length issues, but I would still practice some sanity with using proper sizes and lengths.

With my current setup Mike, what wire size can you recommend if ever I go to the 12v route? No wire will ever go longer than 10 feet.

Thanks!

[Mike90250]

Yes, a 24V system has more leeway with voltage loss, and cable length issues, but I would still practice some sanity with using proper sizes and lengths.

[raymondalmeda]

Your load demands factor heavily in the voltage decision. If you never have over 1,000w of load (including motor starting surge) then 12V would work. If you go above 1,000W -2,000w, then a 24V system is better, less amps at the batteries needed. Above 2,000w, consider a 48V system

Thanks Mike!

I will seriously consider your advice, my only concern is that: Won't a 24v system would make me worry less with the cable sizes and lenght? That's my only reason why I'm considering a 24v setup. Any thoughts on that?

Thanks!