All in One Portable Solar Power Unit: 220V + 12V + 5V + Automatic Battery Charge! ;)




Introduction: All in One Portable Solar Power Unit: 220V + 12V + 5V + Automatic Battery Charge! ;)

My starting point was to see if we can make portable solar power unit:

  • lightweight
  • reliable
  • robust
  • different voltage outputs (including 220V AC)
  • capable of storing energy
  • capable to charge lead acid battery

Answer: Yes we can! ;)

If we well balance size and capacity of the unit, it will be much more useful.

When I search on web, found aluminum "suitcases" which can provide 220V AC output. They are usually very heavy due to lead acid batteries inside and not suitable to carry easily.

Another option was foldable panels fitted to fabric bases. Some of them has voltage regulators for DC output but only 2-3 different DC voltage levels...

Step 1: Main Parts Required

When I found "Seifert Magnus Midi 63" toolcase in local Bauhaus, very delighted:) Eureka!
it was perfectly matching size and specifications in my mind... Made of uv stable polypropylene and black in color. Dimensions 40.0x30.0x6.5cm and around 670 grams. Size well suited for two 10 Watts solar panels, has "ribs" on edges to protect switches and other equipments perfectly. Has handle and locks.

If I design a case for only this purpose, it would be very similar to this :)

Also we need 12V DC to 220V AC inverter. Found this 100 Watts unit on the web.

Sanyo 4S lithium ion batteries with over / under voltage protecting and over temperature protecting circuits.

Two 10W solar panels.

7A Lead acid battery charge controller

Digital voltmeter from Dealextreme

Aluminum composite panels to hold solar panels

Diodes to reduce li-ion battery voltage to start inverter (later you can disable them to save power)

Switches, power outlets, screws etc.

Step 2: Preparing Parts 1

Started to remove aluminum frames around solar panels. You should be very careful to not to break tempered glass on it.

Also removed big connector terminals and make them smaller.

Then fix them to aluminum composite frames by Sika WT40 PU adhesive and test them how to fit inside of the box.

When closed, panels perfectly protected during transportation and storage...

Added two parallel set of three diodes (in series) to reduce top voltage of li-ion pack when required. As they gets hot, prepared cooling fins by aluminum "U" profile. These parts located on left side of the box, well protected ;)

Also bend a small aluminum sheet to hold voltmeter.

Step 3: Preparing Parts 2

Also prepared paper labels for more professional look ;).

I'm printing them to photo paper by laser printer, then cut to required size and use transparent tape for surface protecting.

Back side, using double sided tape and 0.4mm grey pet film for digital screen.

I opened battery pack temporarily to show battery protection circuit here.

Then removed all "outer shell" of inverter to make it smaller...

Step 4: Installation

Here you can find schematics of solar power unit. It is Turkish, but added english explanations on it.


Also added schematic as pfd download and gif format, in English :)

Detailed mounting photos with explanations added. Please note that space for additional batteries if required. Charging leads also stored here...

You can direct power to li-ion batteries or 12V external lead acid battery charging port.

Measure both batteries status whenever you want.

All connections completed based on this schematic and looks like spagetti :)

Actually you do need to open inside in normal operation, so it prepared as little bit tight. Also we have enough space for more li-ion battery packs (for more capacity) and cables etc. inside...

Step 5: Finished! :)

Here you can see control panel of unit.

Also a photo of open position added...

Everything on same (protected) surface and easily accessible.

Working perfectly...

Here are main specifications:

  • Very compact and lightweight, 300x400x65mm outer dimensions, 3.74kg
  • Solar power, 20 Watts, max. charge power 1.1A
  • Internal Li-ion capacity 40Wh (Sanyo batteries, over voltage, power, charge, temperature and discharge protected)
  • Nominal charging time 3-4 hours
  • Outputs: 220V AC, 12.6V DC, 5V DC (by using mobile cigarette lighter adapter)
  • 220V output power is 100 Watts
  • External fully automatic car battery charging port
  • All outputs also available by external car battery
  • All batteries are fused
  • Digital voltmeter and charge status table
  • All controls and outputs are on same side and protected...

I' m planning to add led surface lights on empty surface for an improvement.

Cost is around 220 USD (including some mistakes) but value of the success is priceless :))

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    123 Discussions

    hi, i can't understand how many watts did you get. its 100 watt

    1 reply

    Sorry for delay...

    Nominal power of inverter is around 100 Watts, you can get it around half an hour, or 50 Watts for an hour...

    Great work! :)
    I found this page while searching for portable 220v socket.
    I'm actually looking for portable garden tools, like the hedge trimmer.
    Would this pack be able to power such equipment?

    1 reply

    It depends on the power of inverter and discharging capacity of batteries...
    This one was around 80 watts if I remember it correctly...

    I thought about doing myself one like that. I even sort of did, if you take a look in my instructables. But what I didn't liked about the all-in-one case solution is the fact that you have to keep it all in the sun. A lot.

    Have you tested it? I mean, sure, as a proof of concept it's great, but leave that case out for a full day in a hot sun. You won't be able to touch the solar panels. The case beneath them has no vents and it holds li-ion batteries. Take a look at the chart below. Beyond 40 degrees Celsius, accelerated battery aging sets in. Above 80 degrees you'll get a fire. Even with vents, it will still be too hot. BMS WILL cut down the charging rate, trying to compensate for the high temperature detected. So you'll get undercharged, hot batteries.

    Also, the black plastic case under the intense UV treatment will get brittle and crack. That's from experience. Things aren't better with aluminium boxes, either. As I said, until batteries evolve to cope with high temperatures, their place is nowhere near the solar panels. I can see something like that working in slightly negative temperature environments where the cold would keep things in normal ranges - but the UV argument remains even stronger.

    1 reply

    I'm still using it; about two years, but yes, using li ion batteries in hot environment reduces their lifetime. So, charge capacity is lower than two years before.

    But it never reaches 80 degree celcius which is higher than "vicat softening point" of plastic case.

    BTW, case has uv protected formulation and made in Germany...

    You may put a small fan and extra holes but of course it will also use some of panel's power; or you may put batteries out of the box (under of it as shade) while charging...

    also what are the specs for the batteries and the BMS? Are they 3.7V? How many mah per battery? And finally, you seem to have a switch for either charging an external lead-acid battery with your charge controller.., but for the Li-ion battery, you feed the BMS directly from the solar panels?

    1 reply

    Batteries are 18650 li-ion type and 2200mAh and yes I'm feeding BMS directly from the solar panels.

    Hi, I'm not getting the purpose of the 3S2P diodes configuration.. Why you need them in order to start the inverter with the Li-ion battery? Why would you need to "reduce" the voltage and amp for the inverter?

    1 reply


    we need to reduce voltage to bypass overvoltage protection of DC-AC inverter.

    As it is designed for 12V automotive battery, four serial li-ion battery voltage is too high for it...

    what are the specification for Voltage Protection diodes

    1 reply

    They are reducing voltage around 0.6V each and should resist 3 amps. As we 3S2P configuration, reducing 1.8V @6Amps to start inverter with full li-ion batteries.

    You can use anything similar...

    ..but I will skip the 220v part and emphazize on 5v usb connectivity.

    this is exactly what I am walking around planning to build. Yes!

    I love it looks awesome and professional i would like to see links on all the parts lists to pages giving full details of the parts used for example i googled "Sanyo 4S lithium ion batteries with over / under voltage protecting and over temperature protecting circuits" and nothing useful came up so i went to the sanyo website and it's pretty much useless. however the sanyo website does have some cool looking rack mountable batteries but no links as to where to buy or pricing or exact stats.... I really love what ya came up with here i prefer a 120v, 12v, 5v(usb) output so i'd modify it a bit but that would be much easier with links to the items used :P thanks for the awesome post

    5 replies


    actually I did not buy all parts from internet, but for batteries you cand find here for example:

    My battery pack is not ready made, 4S means four battery connected serial and protection circuit added later on. Batteries glued to each other by cyronacrylate type glue...

    You can find battery pack inside photo in my instructables

    Hello- I admire and respect your work ethic and intelligence and am wondering where you went to school, and also whether your interest in technology and alternative power was encouraged/nurtured by your parents, teachers, or anyone else. I'm trying to identify the missing part in our U.S. educational system that is missing this crucial point. To support curiosity and thinking differently, to enable new ideas to come to light. Instructibles is a good model of how a community can support and encourage while still critiqing in a helpful way.

    I teach solar at a community college in the US. We have a solar club which takes on projects and the students learn as they work, especially from projects such as this.


    thanks very much for your comments, I embarassed so much :)

    Probably this is not related to education system but personality.

    I'm a mechanical engineer worked as R&D manager formerly and like camping so much.

    Yes, Instructables is best site I have ever seen to support thinking differently and distibute ideas all around the world.

    I'm proud to be a part of it...

    Thank you for responding- you are probably somewhat correct. I suppose that anyone with a desire for tinkering will manage to find a screwdriver and something to take apart. I just wish there was more DOING in school, to reach all types of learners. But keep up the good work and passion!