gpn said:
Since I rent I can't do any permanent modifications to the house. This stuff is still very interesting to me so I like to play around and learn. I am building a small off-grid circuit for my shop to run some computers, internet/networking items and small electronic items I want to keep online. We usually get 10-20 power outages each summer due to monsoon thunderstorms. The outages are hard on some things. I'd also like to be able to run my desktop laser cutter when the storms are coming through. That pulls less than 1000 watts. I need to measure that exactly. The laser does not need to be on solar always.
OK, let me try to help so you can think thru options that might work for you.
Power comes from 2 basic sources:
1) Grid - constant and unlimited
2) Solar - variable and limited
Batteries store power for 2 basic purposes
1) As a backup to a power outage - they charge up to float value and sit there waiting to be used in power outage
2) As part of a Solar system - they charge up and discharge down and act as a buffer to supply limited
Some basic options:
If you go APC UPS route - then its easy to imagine Power #1 and Batteries #1. The grid comes into APC and keeps your battery bank charged waiting for power outage, at which point the APC automatically starts delivering power from the batteries to maintain 120v. This whatAPC UPSs are designed to do. APC UPSs are not designed with solar power input in mind.
If you go the Solar route, the power comes in from the Solar Panels -> Charge Controller -> Battery bank. To get 120v out, you hook an inverter into the battery bank and it will create 120v. However, if you draw more in 24hrs than the Solar Panels can produce the inverter / 120v will 'stop' at some point.
Recap:
There are mixed options that combine Grid + Solar power inputs... but they are more complicated than the basics (above).
I would not focus on 'idle power' as the large issue until you figure out your overall design.For example, an AIMS inverter (and most others)are only 86% efficient in producing 120v from a battery. That 14% loss may be as much or more as the 40w/hr idle burn of an APC UPS
It is fun! and I would pick a simpler option and just get started and start learning how things work. If you're like me, it really helps clarify things in my mind to do some hands on!
If you can describe a specific choice you want to explore - e.g. Say off-grid, Panels -> Charge Controler -> Battery -> Inverter and perhaps share the equipment model/sizes - then a more specific discussion can be had.
