In the past few months Ive been designing a high power fully automatic solar maximum power point tracking unit. The tracker can handle up to 200 watts at 45 volts and has a efficiency of up to 97%.

This is a plug and play device. Just plug the solar panel in, then connect the load.

It uses and ATMEL atmega48 processor, to regulate and track. The on-board current sensing can handle up to 10 amps. Tracking efficiency up to 99% and converter efficiency up to 97% mean this is one of the most efficient trackers around. The unit has a very fast response time as well, just 50ms/V, and tracks the maximum power voltage to within +/-0.15 of a volt, thanks to the 10 bit ADC.

Multiple units can used and their outputs paralleled to achieve even higher outputs, up to 2000W.

Very nice!

What is the approx. current consumption when there is no current from the panels (i.e at night)?

OS

Just 2mA.

TonyB wrote:Just 2mA.

Very nice! Can I use this unit to charge my batteries as well? If no, what charger do you recommend? I have two 80W BP panels and two Concorde Sunxtender PVX-2580L 12V batteries in parallel.

Currently I am using a SunSaver MPPT controller but during the darkest months of the year the SS MPPT use more amps than I get in (the SS MPPT uses 35mA day and night).

OS

Looks very nice, is the input scaleble to lets say 50 V and what is the output voltage ? I like a configuration/PPT wich can be adjusted to several battery topologies.

_OS_ wrote:the SS MPPT uses 35mA day and night

Wow thats alot of wasted power. When i put my mppt in sleep mode, it draws less than 1mA. The ones you seen in the picture are prototypes. I am currently working on a production version so you can use it. The new unit will be able to read the battery voltage (or the output voltage) to limit over charging.

Also, this unit has a serial interface which will output information in real-time.

Oboema wrote:Looks very nice, is the input scaleble to lets say 50 V and what is the output voltage ? I like a configuration/PPT wich can be adjusted to several battery topologies.

Yes, with minor software changes, and a higher voltage regulator to power the MCU, i think i can easily achieve 60 volts. Currently it works with solar panels all the way up to 50 volts open circuit.

Hi there.

I am look for an MPPT arrangement for a 120kWp solar array mounted on azimuth trackers to drive a 100kW 460VDC motor that runs with constant load. The system includes a diesel DC generator to run the motor when solar is insufficient or unavailable.

Its all DC. I don't want any AC in the system.

There are no batteries planned for the system, however we could put in a minimal bank (say <5min DC motor runtime for 20% DOD) if that stabilized things and made the MPPT design easier. Although I imagine not having to manage batteries may make it easier as it eliminates the need for charging regimes and carrying out equalisation.

At this stage I have figured out I can have a bunch of parallel strings of multiple Outback Flexmax80's in series. That would be quite cost effective but is not a brilliant arrangement as it will probably result in a higher than desirable failure rate over time given the series arrangement (one fails its string fails and power drops off).

Has anyone got any better ideas?

Is anyone interesting in designing for this application? If we can get a good solution we will do a bunch more sites just like it.

Cheers
Rob

Hi Rob,
Just a few questions, what sort of voltage are you looking to have on the output?
And whats the application?
I can help but need a few more details.
Cheers.

Thanks TonyB

Have sent you a PM with this info.

Cheers
Rob

Why don't share this details in the forum ? I'm also looking for a good MPPT for my boat so maybe the information is usefull to this forum ?

Oboema wrote:Why don't share this details in the forum ? I'm also looking for a good MPPT for my boat so maybe the information is usefull to this forum ?

I 2nd that. Please share with us.

Okay, my mistake, I didn't realise this was so interesting

Its 460V DC.

Its 100kW with a few acres of panels so I'm thinking it won't fit on your boat, but then again I might be assuming something about your boat that I shouldn't

The application is water pumping. Big volumes and big lift.

Something else I should mention. Ambient temperatures get very high as well. Over 40 degrees C is common in summer.

Cheers
Rob

Please cool our pannels that will improve the efficiency a lot an warm days. You mentioned that you will be water pumping so firt pump it through your solar panels.

And for the MPPT it is better to use one MPPT per solar pannel, because of the non matching solarpannels you will not waiste any power there.

Hi Rob,

I don't think the Outback DC MPPT can be stringed in series on the output to achieve 460 volts. But i could be wrong.
Also its gonna be hard for the outback to regulate at the maximum power point with the fluctuating load conditions the motor causes. It might need the batteries at the output, like you mentioned, to stabilize the output a little. Ill have a look around and see if i can source something for you.

Like mentioned above, if you can connect a Boosting MPPT (to boost the voltage to 460 volts) to every panel, and then connect their respective outputs in parallel, i think that would be the better solution.

What sort of solar panels are you using? If you haven't ordered them yet, i know some people that can supply you with Australian certified solar panels at very good (i mean really good) prices. They are mono-crystalline 185 watt panels, and i can get them at prices comparable to thin film. (good contacts).

If your interested, i can design and manufacture a fast transient response (which wont need batteries) Boosting MPPT for your application, if you don't find a solution.

Tony.

Hi Tony

I am interested in the panels

I'd need 600 panels. Anything you can send me would be great.

One MPPT per panel is a very interesting idea.

What is the expected efficiency of the Boosting MPPT?

Can you comment on expected failure rates over a 20 year life?

Thanks again.

Regards
Rob

PM sent.

I was wondering what kind of switching topolgy you use ? I think Buck but you have 6 switching devices, or you running in synchronous mode ? or last option 3 FETs and three diodes in parallel ? Because i also considering building my own MPPT but our boat is limited to 52 V due to regulations. The batterie voltage is 50.5 and the solar voltage is also round the 50 V. I can only think of buck-boost, Sepic, Cuk kind of switching topologies.

Yes.. its a BUCK, with 3 diodes and 3 MOSFETs in parallel.

I explored synchronous design, but found for higher voltage designs, its more complicated and there is not much efficiency to gain. Synchronous is only a real benefit below 10 volts.

Hi,

Looks interesting Is there any chance you will be selling this as a kit or finished?

Best regards,

Jesper Mønsted (Denmark)

Hello again,

A brief follow-up: I found a solution to my particular need so please omit my question just above.

Thank you ...

Jesper Mønsted