generator and PVpanel, setup suggestions?

[grayski41]

If you are only using a 12V system, a diesel genset is WAY overkill, you will wet stack the engine.

do you think i would be better using a 24v or 48v batt. bank opposed to a 12v system?

[Sunking]

do you think i would be better using a 24v or 48v batt. bank opposed to a 12v system?

Lets put it this way. 24volt systems are 400% more efficient than 12 volt, and 48 volt systems are 1600% more efficient than 12 volts at a given current level over a given wire and length..

In addition at 12 volts you are limited to about 1000 watt panel input to a charge controller verse 2000 for 24 volts, and 4000 for 48 volt.

[Perry]

I understand the I**2 X R loss for a given wire size but....

Why can't you just keep adding inverters and more batteries in parallel to make a 12 V system as big as you want?

Assuming I would NOT need 230 V, I was thinking of running one inverter to one side of the panel and one inverter to the other side. If I need more power, I can just install another 100 A 30 circuit panel ($75) and run four inverters at once from the battery bank.

Same thing with chargers. Just plug in a bunch 12 volt battery chargers to the generator. Keep adding them till you hear that diesel motor starting to work hard.

I guess maybe I like the idea of a 12 volt battery bank since you can run all kinds of stuff directly off of the battery bank. Also, seem like everything gets expensive once you go above 12VDC.

[Sunking]

I guess maybe I like the idea of a 12 volt battery bank since you can run all kinds of stuff directly off of the battery bank. Also, seem like everything gets expensive once you go above 12VDC.

Not as expensive as copper, and the amount of power you are going to burn up as heat on the copper. 12 volts is fine for the RV market where wire lengths are very short and power requirement is small, but pretty much useless for an off grid home.

For example would you call 100 watts a large load? I certainly do not, just another light bulb. At 100 watts requires 8.33 amps @ 12 volts. If using the minimum safe wire for 10 amps you need a 18 AWG copper wire. Care to guess how far you can run it before you loose 5% of the power? A whopping 4.5 feet. How do you get around that? Only one-way a lot large copper wire. Lets say you need to go 45 feet in your home. Same 100 watt load @ 12 volts. You need a 8 Awg wire. instead of a wire costing 5 cents per foot (18AWG) you now need wire that cost $1 per foot and need 90 feet of it. Here is the kicker, proper design dictates 2% or less power loss. Now you are up to $3/foot copper cable. Just imagine how much cable you would need to operate a large load like a coffee por, toaster, microwave over, or a refrigerator, or heaven forbid air conditioning. You can run down to your RV shop and buy all of them.

As for just keep adding batteries in parallel is horrible practice. You want to keep any battery string to one single string, not parallel strings. Parallel strings are just about impossible to balance and maintain and just ends up taking years of service life off your batteries.

There is a very good reason electric utilities use high voltage up to 1 million volts. They don't like spending money and passing it on to their customers. Even in th eUSA we use a very low voltage in our homes. Go to Europe or about any other country and th eminimum household voltage is 240 VAC.

[Perry]

As for just keep adding batteries in parallel is horrible practice. You want to keep any battery string to one single string, not parallel strings. Parallel strings are just about impossible to balance and maintain and just ends up taking years of service life off your batteries.

thanks for the info. I guess I need to read up on "balancing" batteries. I have already noticed that when I checked the specific gravity of my two batteries in parallel, they differed somewhat.

[Sunking]

thanks for the info. I guess I need to read up on "balancing" batteries. I have already noticed that when I checked the specific gravity of my two batteries in parallel, they differed somewhat.

Exactly and the reason is you cannot control the battery internal resistances and cable resistance. The problem will get worse over time as the weaker battery just keeps getting lower and lower to the point the plates become fully sulfated.