Setting up an emergency backup system

[snowboarder1087]

Hello, I'm new to this.
I`m looking to set up a backup system that will run five Goal Zero 4.5 watt lights (light a life 350) at their full brightness for 4 hours per night. Plus run my laptop which has a 19V battery at 3.42A (so it I guess it draws 65 watts per hour?) for 4 hours per night. Note: The panel or panels will be set up with only a 10% camber (nearly flat) and facing southwest (I can`t change this- long story).

I have one KingSolar 120 Watt Solar Panel (link)

I`m trying to figure out:
- How big a battery do I need? Any specific recommendations?
- How many 120W panels do I need to be able to recharge the battery enough throughout the day for the stated nightly usage?
- What`s a good quality Charge Controller that can handle all of this?

If you have any other advice or tips or reading recommendations so I can learn more about all this that would be great! Thanks

[inetdog]

Hello, I'm new to this.
I`m looking to set up a backup system that will run five Goal Zero 4.5 watt lights (light a life 350) at their full brightness for 4 hours per night. Plus run my laptop which has a 19V battery at 3.42A (so it I guess it draws 65 watts per hour?) for 4 hours per night. Note: The panel or panels will be set up with only a 10% camber (nearly flat) and facing southwest (I can`t change this- long story).

I have one KingSolar 120 Watt Solar Panel (link)

I`m trying to figure out:
- How big a battery do I need? Any specific recommendations?
- How many 120W panels do I need to be able to recharge the battery enough throughout the day for the stated nightly usage?
- What`s a good quality Charge Controller that can handle all of this?

If you have any other advice or tips or reading recommendations so I can learn more about all this that would be great! Thanks

There are several sticky threads in the Off Grid section that walk you through the process of sizing a system given a knowledge of the expected load and the location.


If you are concerned about short term outages (hours) then a grid based UPS would be more cost effective. You do not want to be continually cycling your batteries when grid power is available.
If you are concerned about days or weeks, then you also need to figure in a supplemental power source such as a generator (or even charging batteries off you vehicle alternator).

[PNjunction]

Snowboarder - knowing your wattage and time of use is great for the lights.

The problem with the laptop is that you will have to measure it to be sure since considerable savings can be had by not recharging the internal battery, running at low cpu speeds and using other power saving measures.

To get a better indication of that, you'll want to use something like a P3 International Kill-A-Watt meter.

For now, you can just burn up a common hybrid / dual-use agm in the 55 to 75ah range.

A Morningstar 10A pwm SS-10-12v would get you started with the 120w panel or a Steca, Xantrex or the like in this quality range.

As you do more reading and measuring, you will be able calculate more accurately your battery needs - which take into account your poor angle, and solar-insolation hours, which at this time are unknown. That poor angle also means a lot of maintenance to be sure that nothing falls onto the panels and stays there, like snow, wet leaves, and other debris which can basically shut a panel down more or less.

Nobody gets it right the first time, so grab a 10-15A Morningstar, Steca etc controller, a common 55-75ah battery and live it up as your "learner" system.

[Sunking]

Your application is not a solar application. All you need is a McGuiver UPS

Battery Charger >Battery > Inverter. Size it correctly and you can run days without power. You would just be throwing money away on Solar