Newbie - just need to power refrigerator during power outage

yakapo7

BB. said:

Just be aware--More or less the rule of thumb is around 500 Watts per every 100 AH for a FLA @ 24 volt battery bank:

• 7,680 WH / 24 volt = 320 AH battery bus (@ 24 volts)
• 320 AH * 500 Watt inverter * 1/100 AH = 1,600 Watts max suggested AC inverter for 320 AH battery bank

Just rough rules of thumbs--But if you plan on drawing 3,000 Watts from your inverter in the future--It would not be a bad idea to double the AH capacity of your battery bank (3,000 Watt inverter @ 24 volts ~600 AH minimum FLA battery bank).

-Bill

Agreed.  I can always add panels or batteries.  But upgrading the inverter would require getting rid of the old one.  This inverter is much more efficient that the cheaper one I was planning on buying.  

mike95490

so, you can use a larger inverter to power a small load, but as long as you operate within the range of the battery capacity and wiring that is existing, you are ok. 
 But really, what's the point here?  You have grid power!  Why the expense of batteries and their life cycle replacements ?  You won't save money, grid power is usually 1/4 the cost of off-grid.   If you are looking for a expensive "UPS" to run your fridge, OK.

706jim

How often do you have grid failure? If not often a fridge can stay cold for several hours if you keep the doors closed.

yakapo7

mike95490 said:

so, you can use a larger inverter to power a small load, but as long as you operate within the range of the battery capacity and wiring that is existing, you are ok. 
 But really, what's the point here?  You have grid power!  Why the expense of batteries and their life cycle replacements ?  You won't save money, grid power is usually 1/4 the cost of off-grid.   If you are looking for a expensive "UPS" to run your fridge, OK.

How much does a Honda generator cost? $2000? My out of pocket for this project will be much less than that. Mainly because I got the new panels from someone who trades me for junk I don’t need, I bought one year old batteries for 1/3 of retail from a golf place. And I found a place to get the other stuff under retail price. Gas generators cost $30 a day to run. I have other reasons for putting this together.

BB.

A Honda eu2200i costs around $1,050.

https://www.homedepot.com/s/eu2200i?NCNI-5

Ran 2x full size refrigerators (around 20 cuft) and one  17 cuft freezer. Plus a 2000 gallon koi pond pump and air pump and a few lights.

All on about 2-2.5 gallons or less of fuel per day.

Used an extended run time fuel cap and tank.
Stored two Honda eu2000i (earlier version) for 6-12+ years (drained fuel and carburetor, a small shot of oil in the spark plug hole)--And they started up after a couple of pulls (get the fuel pumped into the carburetor).

Got a pair of backup eu3000is (my home, and my in-law's) for more money (electric+manual start, 3.4 gallon internal gas tank).
https://www.homedepot.com/p/Honda-3000-Watt-Gasoline-Powered-Electric-Start-Portable-Generator-with-Eco-Throttle-and-Oil-Alert-EU3000iS/206192156
Got a small (good quality) float charger and wired that to the starting battery (hopefully keep the battery "happy" for a few years in storage).
And they are quiet.

-Bill

yakapo7

BB. said:

A Honda eu2200i costs around $1,050.

https://www.homedepot.com/s/eu2200i?NCNI-5

Ran 2x full size refrigerators (around 20 cuft) and one  17 cuft freezer. Plus a 2000 gallon koi pond pump and air pump and a few lights.

All on about 2-2.5 gallons or less of fuel per day.

Used an extended run time fuel cap and tank.
Stored two Honda eu2000i (earlier version) for 6-12+ years (drained fuel and carburetor, a small shot of oil in the spark plug hole)--And they started up after a couple of pulls (get the fuel pumped into the carburetor).

Got a pair of backup eu3000is (my home, and my in-law's) for more money (electric+manual start, 3.4 gallon internal gas tank).
https://www.homedepot.com/p/Honda-3000-Watt-Gasoline-Powered-Electric-Start-Portable-Generator-with-Eco-Throttle-and-Oil-Alert-EU3000iS/206192156
Got a small (good quality) float charger and wired that to the starting battery (hopefully keep the battery "happy" for a few years in storage).
And they are quiet.

-Bill

What are the bus bars for? Can I just connect the inverter and controller to the same terminal on the breaker (positive side) and the shunt (negative side)?  This diagram is not mine, but I’m curious why he is using a bus bar.  

BB.

A member (2manytoyz--not too active lately) has a nice set of pictures and talks about DIY solar (and his evolution from small to larger/old home to new home):

http://2manytoyz.com/ (about 1/2 way down the page)

Bus bars are just a place to connect multiple wires to a common connection (battery bus, etc.). In larger installations, the bus bars also can carry the "bulk current/power" through the interior of the electrical panel from point a to b to c.

Bus bars are usually heavy enough that there should be little voltage drop from one end to the other--Very nice when (for example) connecting parallel battery strings together into one large bank.

Here is a nice example of why bus bars:

http://www.2manytoyz.com/hardware/alt/setup_1482.jpg

Bus bars are generally copper or brass. There are aluminum bus bars--But they are not really recommended unless you know what you are doing (the surface aluminum oxidizes in seconds when exposed to air).

-Bill

yakapo7

Thanks everyone for all your help.  My build is all done.  Everything works.  I couldn’t have done it without the help of this forum.  Special thanks to Bill.  Now I’m ready for power outages.  1.2kw solar array, 7.68kw battery bank, 2kw psw 48v inverter.  

I have a friend of a friend (journeyman electrician) who is going to see if I can wire the inverter to the breaker box with a lockout switch.  

Any tips for me on what to do / what not to do?  

-Right now, the inverter neutral is bonded to the chassis.  I presume that is not what I want if it’s connected to the house.  I’ll need to run the neutral and ground to the bus bars in the breaker box, right? 

Basically, I need to know if I should leave the neutral bonded in the inverter after connecting to the home. 

mcgivor

The problem with hooking the inverter to a distribution panel is there needs to be isolation between the two at all times either manual or automatic break before make transfer switch to avoid possibly killing a line worker or grid feeding into the inverter.

The best method would be to have a small load center powering essential loads fed from the main distribution into a transfer switch with grid  as prime source inverter as backup, always remember lawsuits are generally more costly than inverters, don't lose either. Play safe.

yakapo7

mcgivor said:

The problem with hooking the inverter to a distribution panel is there needs to be isolation between the two at all times either manual or automatic break before make transfer switch to avoid possibly killing a line worker or grid feeding into the inverter.

The best method would be to have a small load center powering essential loads fed from the main distribution into a transfer switch with grid  as prime source inverter as backup, always remember lawsuits are generally more costly than inverters, don't lose either. Play safe.

I understand.  I’d be sure to use a lockout switch like this that forces me to turn the main breaker off before turning on the breaker for the inverter.  

yakapo7