Adding solar to an old on grid homestead

[UrbanHunter]

Thinking about it a little more, if you are only powering your wifi Router you may be able to address your needs with a simple UPS device. I have one for my router and it does okay. The nice thing about a UPS is it has a built in battery, charger, and automatic transfer switch: https://www.amazon.com/APC-Battery-...&hvlocphy=&hvtargid=pla-4583932713467616&th=1

They have about 200 watt-hours of storage, so if your load is less than 20 watts it can cover about 10 hours.
I use one for my router

I tried to use one for the wife's CPAP machine (72 watts) and it was able to work for 3 hours and died. As a temporary solution I used a 12 volt 100 Ah battery and a 300 watt inverter, which could provide coverage for 2 nights, the inverter had USB charge ports, so we could charge a phone off it too.

Her oxygen machine draws 450 watts and the unit in the picture will only cover that for 1 night (10.5 hours) before depleting the batteries.

A single circuit automatic transfer switch adds about $80 a system.

I like measuring my energy consumption using a kill-a-watt type inline meter as part of my system sizing exercise.

 

[Magpie]

Thank you for all of your thoughts - Have to admit I couldn't remember what thread I used to ask! I meant to say I can buy a solar panel for it also, but you probably saw that.
I'll look into the smaller back ups too. So difficult to find that stuff here at a decent price.

 

[UrbanHunter]

So I need to give an update (~2 year anniversary of being fully operational), my system has been working fine, but I have been increasing my loads to get the maximum utilization out of the system. It works okay, but I smoked an ANL Fuse...

This has got me to thinking that I would have been better off to go with a 48 volt system, the amperage would be reduced by 4X and would greatly reduce the size of the wires required. I would have to replace the inverter and low voltage relay controls, but it would not be as expensive as I originally thought. I could reuse all my batteries, heavy duty wires, and the charge controllers can operate on 48 volts. As for inverters, Many of the 48 volt units offer a 120/240 volt option, which would allow for some interesting opportunities.

I know hind sight is 20/20, but I wish I had a clearer plan 2 years ago...

My general observation is that for systems under 1500 watts (delivered power) 12 DC systems are okay, once you break 2000 watts you are better to plan on going with 24 or 48 volts.

This has been a hobby project and my systems' maximum output went from 200 watts, to 1000 watts, and is now at 4000 watts. That last jump requires way too much amperage (~350 amps, Max) for a 12 volt DC system to supply in a reliable manner. A 48 volt DC system could meet that demand with only an 85 Amp draw. Lesson learned. As a stop gap measure, I plan to limit my total system output to 1800 watts Max.

 

[viking]

We ran our motorhome 120 VAC 2,000 inverter/charger on 12 VDC, it was basically a test set up for going to our solar backup system, which runs on 24VDC, we bought the Magnum Energy 4,000 watt pure sine wave inverter because it could be stacked with other same type 4,000 watt inverters but as it turned out that one inverter serves all of our needs, it's also 120/240 VAC, I figured that if I ever had to run a deep well pump this type of inverter could do the job. UrbanHunter, you're really on the mark in going to a 48 volt system, even though I went to 24 volts the feed wires are very large, which equates to much more expense per foot, the prices of copper wire have really gone through the roof, just seeing the price of a 250 foot roll of 12 ga. Romex is enough to give you a heart attack.