solar CHT solar (photovoltaic) system
and other #energetics related questions

Last updated:
    2015-10-11 couture
    2016-03-06 quick sketch of cht4c situation, should prep doc for release
    2017-08-17 restyle
    2017-09-22 update to cht5a state

50W portable solar panel

See 🔗stuff and 🔗ordering for more info!

Related projects
    * / @HSBXL !
    * +chrono is designing own solar charge controller:
    * check "open hardware charge controller":
        * [...]
    * [...]

****** Research: Next questions

    (partly deprecated: main coordinates of what we imagined)

We are moving along with our project, and have some funds available for dive into solar.

Need info around the following basic coordinates:
    * start small and cheap.
    * Looking for:
        * 200W out
        * 5h (1kWh) of battery
        * size & weight optimisation not a must, but would be nice
        * optimizing around price
    * Devices to power are all DC:
        * 2 laptops ~20V 50-90W <-- data via what chargers are rated at 220V ac charger label, not consumption
        * 3 smartphones ~5V 10W
    * That would make it maybe 250Wp (?), but could live with half of that too (?)

Main idea currently:
    * Do it without DC->AC inversion
    * Just pure DC system, with a voltage regulator
    * can build it ourselves

-  - -  - -  - -  - -  - -  - -  - -  - -  - -  - -  - -  - -  - -  - -  - 

    Laptops and dirty power (input voltage tolerance)

    * What happens with a Lenovo X220 if you provide it with wrong voltage / current if it's turned off?
    * ... and if it's turned on?
    * why do laptops actually physically "whir" with the wrong voltage?

    Better than off-the-shelf
Looking at Voltaic etc (below) it seems that we could get by with much less?
maybe a 20W panel + 100Wh (~8.33Ah @12V) battery system (per laptop)?

    Using truck battery to charge laptops

    Deep-cycle batteries
= lead battery designed for repeated discharges + recharges

Cost ~0.5€/W ?
Inverter per panel

    Concentrated water heating -> hot water (heating, bathing, power)

    Solar ovens !!!


Price per watt
Looks like 

Online converter
Convert from Ah to KWh

Formulary (ger) (physic) (en)

General informaton (ger) (calculate solar setup)

^ not actual CHT system ;-)

    Panel materials (Crystals)

Read this first:

For prices, I took a random look through
Not sure if they deliver to Canarias and what the price would be! ->
I sent them an email
UPDATE: they replied
poly 145Wp 18V 240€ (1.5€/W)
mono 45Wp 21V 150€ (3€/W)
thin film 50Wp 21V 100€ (2€/W)
mono 50Wp 12V 60€
mono 160W 200€ (folding portable 2x80W halves zip together)

For more prices etc, see 🔗ordering!

    Charge controllers

Looks like they're 30€. Example:

Get MPPT, up to 40% improvement (I think).

    Ready-made solutions "for nomads"


    * Voltaic systems
        * $400 for 10W + 72Wh batt
        * $400 for 18W 18V + 72Wh batt
        * $170 for 20W , 18V
    * Goal Zero :
        * expensive ~ $10/W
        * Nomad series:


Tila has them. I think mostly because they look cool.
It's not a giant improvement in efficiency. 

    DIY solar

    * :
        going to waste, asking for used "garden lights"
    * :
        lots of awesome links
    * [...]

    Charge battery backpack
* put chargers, devices and possibly extra batteries in a bag + 220v splitter, to be inconspicuous
* just plug that one cable from the bag while #squatworking
* problem: heat? maybe
* what's the fastest (W) one can expect to charge?

    How to power RPi from batteries:
#rpi #solar #energetics

    Max: 2.5A @ 5V, Expected: ~500mA -> 2.5W
    Didn't work from an 550mA Alcatel USB charger, but exits on powerbanks are usually 1A, 2.1A
    Frequent unexpected poweroffs can corrupt SD card
    Roughly (made up :)): hours ~= cap / ( draw - charge/2or3{night} * 0.8or0.9{losses}) >> what's your experience?
    Solar 7W + 5000mAh(=~10h) battery min could work
    Could get a few days on the 3W+10000mAh below maybe (survives ~2nights + 0.5Wcharging)

Less power:
        Have a 5min circuit breaker + OS that takes one measurement, then shuts down (but security won't work that way, just sensors)
        RPi 1 or 2, or zero (zero is hard to get)
        Arduino? base is ~50mA, but at more than 5V... can it easily work with sense hat?

****** Pad / Unsorted

<-------------------------- (new)

    * see 🔗stuff (under energetics) and parts of 🔗ordering for gear info !

    * working on own battery system based on 18650s ("hyperbattery")

    * Solar BMS (Solar Battery Management System) for LiFePO4:
        * Shipping, Ready to buy
        * LiFePO4 is cheaper long term:
            ~2000 (even "up to 8000" cycles, compared to ~500 for Lipo for 2-3x price (or lead acid "250 to 1200")
            however perhaps easier to damage if you're experimenting, and a bigger upfront investment
        * Copyleft hardware designs & firmware !

    * [...]


    * ask corp's for sponsorship ??? (Voltaic, etc)
    * document types, prices and availability of batteries
    * [...]

Solar in Lanzarote

    * Sol-Lar (Canarsol - Lar):
        * at Puerto in Arrecife
        * pics: [img:IMG_20150416_140426974.jpg]
        * 12V 85W 155€ poly (~1.5€/W)
        * 629 16 12 09 (Open Mon-Friday 9-13h)
    * Sun-Telco:
    * people suggest buying from Gran Canaria and shipping in!


Historic primitive, and imagined designs

    System 0 (CHT4b):
        -> solar panel
        -> directly to an old Samsung 19V / 40W laptop with broken screen

It turned on and worked as a regulator to charge USB devices.
Can't verify the laptop worked stable, because broken screen.

    * what could possibly go wrong?

    System 1 (imagined):
        -> solar panel with higher wattage
        -> DC conversion, no battery
        -> directly to laptop

        * CONTRA: You'd need a big panel, probably 100W size (X220 takes 65W)

    System 2 ("DC straight to battery"):
        -> solar panel
        -> DC convert to 11.1V (X220 battery voltage)
        -> charge batteries directly with some contraption to connect them like
        -> switch batteries in laptop

        * is possibly higher / fluctuating current a problem?

        * PRO: awesome because using standard and Li-Pol batteries
        * PRO: can bring with you away, split weight, etc

    System 3a ("DC straight to laptop"):
        -> solar panel
        -> DC convert to standard battery voltage (12V / 24V)
        -> AGM battery ~50€
        -> DC convert to 20V / even better, manual dial-in any DC voltage
        -> plug in laptop

        * CONTRA: two DC converters needed

    System 3b
        -> solar panel
        -> charge controller (12V / 24V)
        -> AGM battery ~50€
        -> notebook power adapter (cigar lighter) ~30€
        -> plug in laptop
        -> all stuff stored in an IKEA box (samla)
        -> battery protector 12€ like]

        * PRO: could be extended by an USB cigar lighter adapter like
            * what happens if the battery becomes almost empty? Is it better to use a constant current source?

    System 4 ("standard solar"):
        -> solar panel
        -> DC convert to battery
        -> AGM 12V battery / series of batteries
        -> inverter to AC 220V
        -> laptop adapter to 20V DC

        * inverters to AC 220V are / seem expensive (~150€ for 300W):
            UPDATE: not really. see 🔗ordering
        * Q: how much do you lose with DC -> AC -> DC conversion?:
            Probably least 20-30%.
        * but you can plug in anything which is handy!

    Cht4b Status (June 2015)
    * Bought:
        * 50W SolarWorld panel (for 90€):
            (classic poly-crystal panel)
            outputs ~18-21V
            ~1x1m, ~5-6kg
        * DC-only, to charge laptop (Lenovo X220)
        * laptop accepts 20V 3.25A / 4.5A. Unsure about tolerances / dangers?
        * Battery in laptop 11.1V
        * can charge devices on 5V USBs via laptop

    Cht4c Status (March 2016)
    * Bought:
        * Battery
        * Charge controller
        * Step-Up voltage regulator
    * Powering with up-regulator:
        * (Cinch-based connector setup (temporary hack))
        * Lenovo X220 ~20.5V
        * sound system ~15V, takes 20V
        * Apple Macbook cable (16V, still works ~18V)
    * Powering direct from battery:
        * LAN + WLAN direct from battery (12V)
        * 3.5" disk drive (unstable!)

    Test setup Germany (Gerrit)

Instance of 3b (above).

        * 12V x 12Ah = 144Wh AGM battery (for 28€):
        * 20Wp mono solar panel (for 32€):
        * 12V cigar ligher (for 8€):
        * charge controller (for 26€):
        * notebook power adapter (cigar lighter) ~30€:
        * battery protector 12€:
   included in this charge controller      

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