#298589 - 03/10/21 01:29 PM
Re: Solar Power 101 (Updated with link to video)
[Re: Blast]
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Geezer in Chief
Geezer
Registered: 08/26/06
Posts: 7705
Loc: southern Cal
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Thank you very much. Good stuff....
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#298594 - 03/10/21 11:46 PM
Re: Solar Power 101 (Updated with link to video)
[Re: chaosmagnet]
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INTERCEPTOR
Carpal Tunnel
Registered: 07/15/02
Posts: 3760
Loc: TX
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34000 mAh is 34 Amp hours, not 34 Amps.
34 A * 12 V with inefficiencies is more like 350 W, not 450 W.
Where you have Watts * hours above, your resultant unit should be Wh.
I’d suggest both another panel and also a deep cycle battery (Lithium if you can afford the upfront cost — they have a far longer cycle life than AGM and other lead-acid battery types) for charging everything. D'oh, thanks for the corrections! Trying to figure out how much extra "oompf" to include in a solar system is a weak point of mine...along with math. -Blast
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#298650 - 03/17/21 11:12 PM
Re: Solar Power 101 (Updated with link to video)
[Re: Blast]
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Geezer
Registered: 06/02/06
Posts: 5357
Loc: SOCAL
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A few random thoughts...
The number of solar energy watts theoretically hitting your solar panel is not the number of watts in 12 volt DC going to your battery storage. Expect system losses of more than 10%.
In the informal experiment I ran a few years back, the closest I got was ~70% of the number in a panel’s name. One of the 21 watt panels actually measured out at 14.3 watts — that’s at roughly solar noon on a nice sunny SOCAL day. Add some clouds and move the sun left or right of center and I would expect the numbers to drop off.
My only recommendation is to buy a bigger panel than you expect to need. Then test it before you need it to make sure you have all the wires/cables to make the system work.
I have a 100 watt panel and Renogy Wanderer Charge Controller. No affiliation. The smaller, portable units you might throw in your backpack to take hiking/camping came with built in controllers and USB output.
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#298653 - 03/18/21 02:46 AM
Re: Solar Power 101
[Re: Blast]
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Carpal Tunnel
Registered: 04/28/10
Posts: 3152
Loc: Big Sky Country
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Great thread! I need to need to get a solar rig I can carry backpacking and as an emergency power source at home.
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“I'd rather have questions that cannot be answered than answers that can't be questioned.” —Richard Feynman
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#298658 - 03/18/21 03:55 PM
Re: Solar Power 101
[Re: Phaedrus]
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Geezer in Chief
Geezer
Registered: 08/26/06
Posts: 7705
Loc: southern Cal
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I am on the same quest. So far, it seems that a feasible, fairly light rig for overnights and short trips where you might want to perk up your phone and maybe a headlamp would involve a power bank and not a solar panel.
My favorite power bank for this niche usage is a Goal Zero micro Charge lantern which also functions as a flashlight, lantern (with two power settings) and a usb port for charging other items. Very limited capacity because the 'power bank" is an 18650 battery with a capacity of 2600 mAh....But probably OK for short trips.
You can get larger power banks and at some point it will make sense to throw in a solar panel. From what I have read, solar panels hung on your pack are not really all that effective.
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#298660 - 03/18/21 04:12 PM
Re: Solar Power 101
[Re: Blast]
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Carpal Tunnel
Registered: 04/28/10
Posts: 3152
Loc: Big Sky Country
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Yeah, for short trips a power bank is likely the way to go. But I usually get a couple of week-long trips in each summer. Hopefully my recent shoulder injury will be healed enough to do it again this year. A buddy of mine and I have a spot where we will hike back along a string of mountain lakes camp at one of 'em about ten miles in. A light weight solar charger would be handy for topping off batteries for flashlights, GPS, etc.
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“I'd rather have questions that cannot be answered than answers that can't be questioned.” —Richard Feynman
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#298661 - 03/18/21 04:34 PM
Re: Solar Power 101
[Re: Blast]
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Crazy Canuck
Carpal Tunnel
Registered: 02/03/07
Posts: 3223
Loc: Alberta, Canada
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I can see the value of a solar charger in a base camp, since you can choose a good location in the sun and let it trickle away all day. The pics you see of people hanging them off their backpacks are mostly marketing IMO; the panel will not be getting direct sunlight much of the time.
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#298662 - 03/18/21 05:14 PM
Re: Solar Power 101
[Re: dougwalkabout]
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Geezer in Chief
Geezer
Registered: 08/26/06
Posts: 7705
Loc: southern Cal
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An additional note. The Goal Zero product I mentioned is listed as "out of stock" currently. Hopefully it will return, but who knows??
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