Doubling up solar panels

Discussion in 'Gadgets & Tech' started by OwenM, Nov 7, 2019.

  1. OwenM

    OwenM Ultralighter

    I've just got a new solar panel, it has one UBS socket on the back. If I were to connect it to a two into one coupling and put another panel into the other connection, would that be in series?

    Could I use this to charge up a powerpack or would the voltage be to high?

    It's so long since I did any electrical stuff I've forgotten how to do the maths.
  2. tom

    tom Thru Hiker

    The power question is quite straightforward - if you run them parallel (joining 2 - wires and 2 +wires) you double the power, if run them in line you increase the voltage. But it gets complicated how to use it - some devices use a higher voltage for fast charging, others use higher power. Fast charging plugs that come with a device usually state which method in the tiny printing ....
  3. Foxster

    Foxster Ultralighter

    I'd say you'd be connecting the panels in parallel i.e. you should get the ~5V you need to charge your phone etc., not a potentially damaging 10V. Might be complicated by any additional electronics in the panels or the coupler but that would just degrade the power or stop it working rather than damage your device.
  4. OwenM

    OwenM Ultralighter

    Thanks, I think it should be OK, if it starts getting hot I'll unplug it quickly. Just ordered the connector and lead so if we get any sun at the weekend I'll try it.
  5. Foxster

    Foxster Ultralighter

    In my experience though, the UK doesn't get enough sunshine for solar panels to generate enough power to charge a smartphone.
  6. cathyjc

    cathyjc Thru Hiker

    I've used a small solar panel to charge a small battery pack - laid out in the sun on the window sill, in UK - ideal conditions.
    But we all know that's not quite how it is out there when hiking …….
  7. Foxster

    Foxster Ultralighter

    Yup, a little battery in ideal conditions is about as good as it gets. I bought a £50 Anker panel that weighed 300g and even with it exposed to the sun on the top of my rucksack all day it added nothing to the connected powerbank.

    You need 12 hours of direct high-in-the-sky sunshine and a stationary panel to make any useful power.

    I messed with generator stuff a year ago. I tried solar, thermocouple, piezoelectric and wind. Nothing was practical at a useful weight. I'm back to taking a decent-sized powerbank.
  8. Teepee

    Teepee Thru Hiker

    Anker 21w panel-1-2.jpg View attachment 19889

    One of these charge analizers will tell the story of whether its working or not. This exact setup when plugged into my Samsung S9 phone, saw it deliver just 0.8 A.

    I've found that it's not just the solar panel(combined with efficent circuitry), but the powerbank too. If you charge a phone directly, It'll switch charging rates and cause the phone to notify you/change charge rate; it's really inefficient. Some powerbanks take charge better than others; my Anker and Lidl being the best out of 8.

    This is a 21w Anker, plugged into a 26800 mAh Anker, on a bright but overcast day in mid Sept. It delivered this current all day at home dangled vertically out of the window and facing S.

    However, It didn't make the cut for the last 10 dayer in Norway charging my Nikon batteries. The sums didn't add up and I made the right decision (again) by taking powerbanks instead.

    Dry 4 day plus spring/summer trip with no rain? yes. At all other times, it's a no for me too.
    Last edited: Nov 7, 2019
    gixer, MartinK9 and edh like this.
  9. OwenM

    OwenM Ultralighter

    Been using a 12W panel for the past five years. It folds in half for carrying and weighs 300g including the cordura case. I've always managed to find enough sun to keep my inReach, phone and Kindle topped up on long walks in Scandinavia and Scotland. I've not tried hanging it from my rucksack. I just set it up when I set up camp and make use of the long summer days.

    The new one is 10W but is the same size as half of the old one, it doesn't have a case so only weighs 75g. If I can double it I'll have a little more power at half the weight.
  10. Clare

    Clare Thru Hiker

    I took a yolk panel to the Pyrenees but I was never stationary long enough while the sun was high. By the time I was stationary optimal conditions were finished. So even in dry and hot weather it didn’t justify its weight. The following year I took the extra weight of a bigger power bank instead.

    I would take a panel if I thought I wouldn’t get to a plug for 7 days, or was planning to have 3 hour lunch breaks to charge from the panel.
  11. Foxster

    Foxster Ultralighter

    The power source I can see being potentially better than solar panels is a Radioisotope thermoelectric generator (RTG). Trouble is that if you try to get your hand on some Plutonium 238 or something similar to make one you get men in sunglasses knocking at your front door in the middle of the night. Spoil sports.
    Teepee and Lempo like this.
  12. Patrick

    Patrick Trail Blazer

    I'd echo OwenM - 10w panel effective at keeping a phone or powerbank topped up on a longer trip. Not much use just dangling off the rucksack, but a couple of hours set up at a good angle in bright sun can fully charge my phone (probably about 2000mAh) from flat. Its not that hard to find a suitable opportunity in summer unless you're really powering on for every hour of daylight.
  13. Enzo

    Enzo Thru Hiker

    Those power ministers are well worth the investment.
    I tested a half dozen usb leads, there was a huge range in the current they passed, could easily be the difference between a panel charging your phone/bank or not.
    Teepee likes this.
  14. Clare

    Clare Thru Hiker

    what are those things, power ministers? I looked on amazon for battery tester but didn't get that tiny thing with usb ports. what's the correct name?
  15. Foxster

    Foxster Ultralighter

    Try "USB power monitor".
    Clare likes this.
  16. tom

    tom Thru Hiker

    My panel fast charges my phone at good speed (even between 5 and 6 in the afternoon) but useless to charge powerbank (so slow...). Panel on packpack while hiking is also a waste of effort (I can hear constant switching and get hardly any charge with the constant movement and change alignment to the sun). Lunch breaks get excellent topup results...
  17. OwenM

    OwenM Ultralighter

    Well the connectors arrived today so I set it up on the windowsill using the new and old panels. Only weak winter sun through clouds today but the light is on and it's producing some power. Don't have a monitor so I can't say how much but in principal it does work.

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