MPPT v Steca

Hey guys,

Ok so don't want to start a ww3 debate here but looking for some advice. Will be using a 120w panel to charge 100ah battery which is running a 40l fridge. Will be camping in NSW in both winter and summer. Will hopefully not be letting the battery discharge below 50% but a couple of cloudy days and it could happen.

I want a good regulator with a detailed LCD display.

I am currently tossing up between either the Steca 2020 or the MPPT with the additional LCD display offered by batteryvalue.com.au

They are around the same price so there is not cost saving to be had either way.

I can't seem to find any info on the battery value MPPT except what batteryvalue has posted on these forums. Does anyone have any first hand experience with this regulator.

Basically I am wanting to know if I'm better off going with the MPPT over the Steca and if the MPPT LCD display is as detailed and user friendly as the Steca.

Any help would be appreciated.
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Reply By: Battery Value Pty Ltd - Friday, Apr 27, 2012 at 13:30

Friday, Apr 27, 2012 at 13:30
Hi Simon,

the 2020 is a PWM solar controller, while ours features true MPPT with modified multistage charging algorithm, battery temperature sensor and other battery life extending features.

One of the advantages of true MPPT over PWM is that you can select any solar panel voltage (up to 100V for our unit).
The inbuilt DC/DC converter then converts the high incoming voltage to the momentary battery terminal voltage.

Higher solar panel voltage means you can 'string' several 12V panels (wire them in series) for less voltage drop (power loss) in the wires, and also achieve greatly increased partial shade tolerance.
The same partial shade tolerance can be achieved by using one or two correctly bypassed 24V panels.
There's a youtube for more details:
partial shade tolerance



cheers, Peter
AnswerID: 484368

Follow Up By: Simon H1 - Friday, Apr 27, 2012 at 13:38

Friday, Apr 27, 2012 at 13:38
Hi Peter,

Thanks for your response.

Just wondering if there is any benefit from wiring the panels in parallel instead of series? Ie do I forgoe anything by not wiring them in parallel?

Also if wired in parallel is there any significant benefit of your regulator over the Steca 2020?

And finally the LCD add on for your reg, I have not been able to find out much info on these, but are they as comprehensive and user friendly as the Steca? For exmaple will they tell me the current amps being output by the solar panel, the amps being used by the load, the SOC of the battery etc etc?
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FollowupID: 759631

Follow Up By: Battery Value Pty Ltd - Friday, Apr 27, 2012 at 14:53

Friday, Apr 27, 2012 at 14:53
You're welcome Simon,

as long as all panels are of the same wattage, there's no benefit of wiring 12V panels in parallel over wiring them in series.

Say you wire 2x12V panels in parallel (the typical folding panel configuration):
it only takes one cell to become shaded out, and you lose 50% of charging amps.
In a 2x12V series string, the same amount of shading reduces the charging amps by only 25%.
Of course your solar regulator needs to be of the true MPPT type for this.

As indicated above, only when you have a mix of different wattage panels, it is better to wire them in parallel.
Not that you would get maximum power from any of them, but you get good power, while in a series configuration you can't utilise the power from the smaller panel at all.

If wired in parallel our MPPT regulator achieves still higher charging amps compared to PWM, as long as the battery voltage is still low, and the ambient temps are also low. Once battery terminal voltage creeps up, and cell efficiency drops due to high operating temperatures, the MPPT advantage shrinks in this comparison.

Our MPPT solar regulator with modified multistage charging algorithm is capable of precisely charging the battery to 100% full, without applying unnecessary over-charging (which would cause battery dry out in the medium term).
It's very robust because it cannot get confused by any load currents during charging (e.g. by a fridge with constantly changing power drain).
Most if not all solar regulators in this price range don't get the absorption/float switch over right causing dry out, especially in a 24/7 situation.

And the best feature is the electronically limited max charging current of 10A.
This means the unit self protects itself from too big a solar panel connected to it. Now you can connect a high wattage panel for higher charging amps on overcast days or early morning/late afternoons.
Typical PWM solar regulators on the other hand would overheat when the max specced panel power is exceeded.

Yes, the remote control/display units are fairly comprehensive.
You can select display of incoming V,A,Ah,Wh, the same goes for the load, you get to see battery current (- signed means discharging current, unsigned means charging current), battery voltage. You also can observe the battery temperature, temperature coefficient display/adjustment.
You can also adjust the absorption stage end voltage for different types of batteries in 0.2V steps.
The only thing is SOC which is derived from the battery voltage, thus is quite inaccurate.
Another feature lets you remotely turn on/off any load connected to the MPPT solar regulator by pressing a button.
Use an inexpensive networking cable to extend the distance between the two by several metres (I think 12 metres is the specced maximum when using cat5 wire).
1.5m wire comes standard.

cheers, Peter

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FollowupID: 759640

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