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New poormans backup power system

G Hale

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Oct 14, 2021
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I'm just finishing a small backup system installed in a shed. 300 watts solar 30amp charge controller 110ah Sla battery, 1100 watt inverter. During a power outage I hope to run a small led tv or 2, 3or 4 9 watt led bulbs and a WiFi router for 5hours. I also hope to be able to charge phones, etc with the 4 USB ports I have. How practical does this sound? I'm in sunny California.
Feb 2022 update
I now have 400 watts of solar and 220 AH of batteries. I'm running the inverter 24/7 powering internet modem and router, a desktop phone, 2 laptops, 2cell phones, and living room lighting. All in all I am pretty satisfied with this system.
Fer other novices out there, I have learned a few things. 1 Spend the extra money for a pure wave inverter. 2 Spend the extra money for a good charge controller. 3 If your budget allows buy lithium ion batteries. I bought SLA batteries and they are doing fine but the lithium have a longer life and can be discharged much more.
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Did you figure the total power consumption of the loads yet?
I assume you have 12V system using SLA 12V 110Ah which will provide you about 12V x 55Ah = 0.66KWh of power.
So if you want to run the load for 5 hours with your batteries, which means the 132W load will run for about 5 hours, but it will be actually less due to system loss and the inverter efficiency.
It will be better to get 12V LED bulbs so no need to run them through the inverter.
 
How many watts do the TVs and router use? Add those wattages up to the 27W or 36W being used by the LED lights. Once you have that total wattage.

Your battery is 12V 110Ah which is 1320Wh. But you can only discharge to 50% so you can use 660Wh. Divide that 660Wh by the total wattage of your devices and that tells you how long the battery can power the devices without any charging (or at night when there's no sun).

For the solar you have 300W. Assume you might get 6 good hours of sun on average and that gives you 1800Wh of power in a day. So your panels alone will power your devices three times as long as your battery alone could. This assumes ideal conditions such as good sun and perfect solar panel angle.
 
which means the 132W load...
The OP doesn't have a 132W load (as far as we know). Your math states that the OP could run a 132W load for 5 hours given the battery. But if the OP has a 200W load or a 50W load then of course the runtime will be different than 5 hours.
 
OP: "During a power outage I hope to run a small led tv or 2, 3or 4 9 watt led bulbs and a WiFi router for 5hours"
OP wants to run the load for 5 hours during power outage.
I just give out the calculation based on batteries power, so OP can have loads up to 132W, and I did ask OP to get total load so he can calculate run time as I show OP how to figure it out.
 
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Sorry wattage is just under 150w
Then your battery alone will run those loads for a touch over 4 hours and your solar alone will run them for close to 10 hours.

If you only need to run those loads when the sun is out then you'll be fine with the amount of solar you have. Even if you only get 150W out of the panels you can run the 150W loads for 5 or 6 hours.
 
Sorry wattage is just under 150w
So it will be less than 5 hours based on the batteries you have (if the batteries are in perfect condition of course). During good sunny day your Solar system can easily provides enough power to run your loads.
 
Did you figure the total power consumption of the loads yet?
I assume you have 12V system using SLA 12V 110Ah which will provide you about 12V x 55Ah = 0.66KWh of power.
So if you want to run the load for 5 hours with your batteries, which means the 132W load will run for about 5 hours, but it will be actually less due to system loss and the inverter efficiency.
It will be better to get 12V LED bulbs so no need to run them through the inverter.
Thanks Bud. I do have 12v led bulbs but the inverter has to run for the woman to have tv and myself WiFi.
 
I'm just finishing a small backup system installed in a shed. 300 watts solar 30amp charge controller 110ah Sla battery, 1100 watt inverter. During a power outage I hope to run a small led tv or 2, 3or 4 9 watt led bulbs and a WiFi router for 5hours. I also hope to be able to charge phones, etc with the 4 USB ports I have. How practical does this sound? I'm in sunny California.View attachment 68812View attachment 68813
Thanks everyone i've already learned what I assumed that battery is my weakness. For now I will get the load under 1oow intill I can get another 1ooah of battery.
 
Your current battery is fine depending on what part of the day you need to power the loads. The panels will run the loads while the sun is out (roughly mid morning to late afternoon) and the panels will keep the batteries charged. If you need to keep using the loads as the sun sets then the batteries will keep you going a few more hours into the evening. If it's sunny the next day you get another whole day of use and a bit into the evening. Repeat every sunny day. You will need more battery if you need to run the loads more into the evening or on days with no sun.
 
Your current battery is fine depending on what part of the day you need to power the loads. The panels will run the loads while the sun is out (roughly mid morning to late afternoon) and the panels will keep the batteries charged. If you need to keep using the loads as the sun sets then the batteries will keep you going a few more hours into the evening. If it's sunny the next day you get another whole day of use and a bit into the evening. Repeat every sunny day. You will need more battery if you need to run the loads more into the evening or on days with no sun.
Thanks Maddy, I will do as you suggest if we have an outage soon. Where we are the e wildfire danger is great. Our power company shuts down on really windy days to avoid starting more fires. With any luck I will get more battery storage in a month or two. I'm doing this on social security retirement and fighting cancer at the same time. I can't lift a battery over 55ah so I'm hooking them parallel.
 
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Perhaps as I learn it may help other newbies. The advice posted her was very accurate. Today I ran a 47inch tv and a 100watt equivalent (14watt) great in full sun. Mow the panels have been shaded for an hour and voltage is 12.6 I would estimate I have another 60-90 minutes above my 12.3 volt self imposed cut off. Thanks everyone.
Edit, it is 9pm and I just powered the inverter off. Battery bank was at 12.4 v so I basically ran a light and tv , using 147 watts, nearly 5 hours during full sun and 5 hours after we lost the sun. That's with 200 watts of PV and 2 55ah batteries.
 
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Is your router DC?
Even if it plugs into an AC socket it is really DC. Just about any electronics device with a power cord containing any sort of rectangular box is a DC device. The router (or the power cord box) probably shows the DC volts. With the right adapter the router can probably be run off of the battery.

The TVs can probably be adapted to run off of DC. Use some DC LEDs and the inverter is no longer needed. That will give more runtime.
 
Even if it plugs into an AC socket it is really DC. Just about any electronics device with a power cord containing any sort of rectangular box is a DC device. The router (or the power cord box) probably shows the DC volts. With the right adapter the router can probably be run off of the battery.

The TVs can probably be adapted to run off of DC. Use some DC LEDs and the inverter is no longer needed. That will give more runtime.
Thanks, the router is 12v, 12v lights are no problem, I can look into 12v tv's. Z
 
Thanks, the router is 12v, 12v lights are no problem, I can look into 12v tv's. Z
Keep in mind that your 12V system isn't really 12.0V. It can be a couple volts more or less. Verify how tolerant those DC devices are. You might need a DC-DC converter that accepts something like 10-14VDC and outputs a steady 12.0VDC. You can wire up a DC fuse box to that steady 12.0V output then your DC devices will only ever see 12.0V and not a range of voltage as the battery is used.
 
This is my poorman’s gateway drug project. Keep everything 12VDC for simplicity, and no inverter losses.

I use a trash-picked Belkin UPS for regulated power to my sensitive router and modem. Output and charging is 3A. Everything else in my office (Surface tablet car charger, fan, lights, USB ports) I connect direct to the battery as they are unaffected by the swing in voltage. Easy to find used cheap units on eBay.

I have a single Harbor Freight 35AH AGM which will run the system for 1-2 days. Your 110ah battery will be sufficient if you are efficient.
 

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Good for step#1
Step#2 would be running some items 24/7 off the available solar energy while waiting for that blackout, Is your router 12v DC?
Yes it is and I can do some lighting at 12v DC and turn the inverter off until needed. If I follow you correctly.
 
ssume you have 12V system using SLA 12V 110Ah which will provide you about 12V x 55Ah = 0.66KWh of power.
So if you want to run the load for 5 hours with your batteries, which means the 132W load will run for about 5 hours
Edit, it is 9pm and I just powered the inverter off. Battery bank was at 12.4 v so I basically ran a light and tv , using 147 watts, nearly 5 hours during full sun and 5 hours after we lost the sun. That's with 200 watts of PV and 2 55ah batteries.

The power of wisdom making wildhat guesses!
 
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