Solar MPPT Regulator/Charger

Maximum power point tracking (MPPT) is a technique that charge controllers use for wind turbines and PV solar systems to employ and maximize power output.

I've seen a lot of MPPT's out there but it has been hard for me to find an MPPT that works at low voltages range or in small projects (0v - 6v).
Most of the MPPT's I've seen on stores are for battery cars and for big solar panels.

What I've been looking for is an MPPT that works up to with an input up to 6 to 8 volts.
I tried making one myself, but I'm not skilled enough, yet.

Can anyone help me find a chip, module, tutorial on how to make my own, or something related? (within the range of 6v max)
I'm also in a budget. A less than $20 budget. Otherwise, I'll be on a ramen noodles diet for the next week.

Links that I've already seen:
sparkfun <-- Requires a minimum of 6v, which is my maximum.
Instructables <-- Requires 50W

I saw this video and around 5 minutes into the video he demonstrates the differences of having a direct solar cell with a diode to charge vs the MPPT.

Of course, he is using a super cap at 2.7v, and an MPPT that cost about $80.

You could build one , but at very low power levels they make no sense, which is why there arnt any tutorials or existing products ,as the cost of the parts to build the MPPT, will be greater than simply buying a slightly bigger Solar Panel.
You really need a Solar Panel of 100 Watts or more before MPPTs are a sensible option.
They are also not that easy to build and fault find , so its not a beginners project.
Regardless of what power level or voltages the design is always the same.
You need a switch mode voltage converter, (usually a Micro controlled buck converter), but if the input voltage is lower than whatever you are trying to charge then buck / boost converter is needed.
You need both voltage and current measuring of the Solar Panels output, and measuring of the output voltage of the MPPT.
You need a Micro of some sort, an Arduino is plenty good enough, and an understanding of MPPT tracking algorithyms, of which there are quite a few, some more complex than others.
Realistically, building one for less than $20 will be a tuff ask.

mauried:
You could build one , but at very low power levels they make no sense, which is why there arnt any tutorials or existing products ,as the cost of the parts to build the MPPT, will be greater than simply buying a slightly bigger Solar Panel.
You really need a Solar Panel of 100 Watts or more before MPPTs are a sensible option.
Realistically, building one for less than $20 will be a tuff ask.

Hi, thanks for answering. So, for low power projects (0 to 6v @ 0 to 2amps) would I be better sticking that solar output to a li-po battery controller (with the appropriate precautions)?

Thanks!

MPT612-Efficiency up to 98% of solar energy conversion chip

http://forum.arduino.cc/index.php?topic=335742.msg2356916#msg2356916

sonnyyu:
MPT612-Efficiency up to 98% of solar energy conversion chip

MPT612—效率高达98%的太阳能转换芯片 - #3 by sonnyyu - 中文 (Chinese) - Arduino Forum

Thanks, Ill look into that.
Looking into a cheaper solution.

The cheapest simplest solution is usually the best.
Buy a Lipo battery that has over and under voltage protection built in, and simply connect the solar panel to the battery via a diode, to prevent reverse current back thru the Solar Panel.

mauried:
The cheapest simplest solution is usually the best.
Buy a Lipo battery that has over and under voltage protection built in, and simply connect the solar panel to the battery via a diode, to prevent reverse current back thru the Solar Panel.

I read that there might be a mismatch on the current thus not being efficient.
Here is something interesting worth reading, it's about CubeSats. Scroll down until you see the Abstract section.

In case anyone is wondering, there are several MPPT projects in the wild where people are trying to build a controller for minimal cost.

Here is one that I have been following:

MPPT is really only effective if the Solar Panel voltage is significantly higher than the battery voltage, what voltage is your P.V. Array?

Pringles:
Can anyone help me find a chip, module, tutorial on how to make my own, or something related? (within the range of 6v max)

The MPPT we used on $50SAT was designed to keep a single Lithium Ion battery charged, the solar controller board both ran the MPPT for the 4 banks of TASC cells and kept the Lithium battery charged.

There is a dropbox link on the website;

http://www.50dollarsat.info/

Where you will find the details.

It worked very well .....................................

The MPPT on $50SAT was based on the LTC3105, there were 4 channels, one for the panels on each side of the satellite.

Circuit diagram here;

LTC3105 MPPT

The board size was 40mm x 40mm.