Customer Reviews

Sunforce 60032 30 Amp Digital Charge Controller

5 star:		(19)
4 star:		(9)
3 star:		(3)
2 star:		(3)
1 star:		(2)

 

 

If you've read the reviews, by now the acronym MPPT has shown up more than once. If you know what that means, read no further as this is not too entertaining. If you would like to know the difference in MPPT and non-MPPT solar regulators, and can tolerate some basic math or skim through it, read on and I can explain why this non-MPPT regulator will do the job, just not the BEST job possible.

MPPT stands for Maximum Power Point Tracking, which sounds like a good thing, and it definitly is a must for large house size systems, but what exactly is it? Simply put MPPT finds YOUR solar array's Maximum amount of power for a given condition (full sun/overcast/panel tilt). It is always searching for the best voltage and current conditions to maximize power from the panels, which after all is what you paid big bucks for, right?

Let's explore how MPPT works. Normal power regulators like this one interface between the solar panel array and the storage battery. When the battery is full, they quit charging to protect the battery from boiling the electrolyte away. Pretty simple. But what if you need more power from your solar panels than the simple case? It turns out that MPPT can, using more electronics and some intelligence, harness more power from your solar arrays than a simple on/off charge regulator. How? by using a small IC chip that searches for the highest POWER from the panel, hence the name maximum power point tracking. The tracking just means that as the sunlight changes, so does the maximum power location.

Unfortunately Solar Panels are not just a source of simple DC power - that is they don't behave like a battery does. The fewer amps you draw from the panel, the higher the panel's voltage across the wires becomes. This is where most MPPT discussions end but with a couple simple equations (ohm's law) we can dive deeper into what MPPT does and why its good (and costs more).

Ohms law is really simple: there are two parts: Voltage = Current times Resistance (V=I x R)
Of course we can re-arrange it other ways: R = I/V, I = V/R Where I is in amps, V in volts, R in ohms. If we connect a 1 ohm (R) resistor across a 12V battery (V) then solving for I must be 12 AMPs flowing through the resistor.

For POWER (one P in MPPT) we need to know another simple equation Power = Volts x Amps (DC version)
In the above example, the resistor is most likely a power resistor (i.e. big) because 12 volts x 12 amps = 144 watts which gets hot real fast. In this case, the 144 watts is a power point from a battery. They are simple since small currents do not make large swings on the battery voltage and we can assume it to be nearly constant when using large storage batteries. Solar panels are quite the opposite - their voltage changes with current change. With power being the multiplier of voltage and current, you can see how this function can be maximized, which is the aim of a MPPT tracker. So how do they work this magic? read on....

Finally we need to know a little about DC to DC converters, as they are the logic controlled core of the MPPT solar battery charger. True they don't convert DC directly to another DC voltage, but they are pretty efficient (97%+) by taking an input DC POWER, making a AC voltage from it much like an inverter would, then converting that AC back to DC again for their output to the battery. And they may alter the battery voltage depending on temperature for optimal charging or even change the voltage depending on how many cells you choose to make a battery array (e.g. 12V, 24V, 48V etc). They are flexible and always seek to get as much power from your solar array as possible and put as much power in your batteries until they are full. Some models take the remaining power from your array and produce AC to be sold back to the utility company, but not all have this feature. Big Solar systems can use 6000 watt DC/DC converters that have a 240 Volt AC output as well. They are not small or cheap but they do work.

How does MPPT work? Shine a constant amount of light on a solar panel so that it's output can be characterized. A "12V" panel isn't really 12.000 Volts. It may be 16-19 Volts if you put a digital voltmeter across its output terminals. This is known as it's Voc or Voltage, open circuit meaning zero current flows because the circuit is open. The compliment to Voc is Isc which stands for Current (I) short circuit. Very few devices can have the Isc measured directly, but for small (60W give or take panels) it is safe to put an ampmeter across the same two wires from the panel and know how many amps flow when the voltage is zero (it's zero because you shorted the wires with the ampmeter - the definition of zero volts is a short circuit) If you were to plot on the X axis of a graph voltage, from the two endpoints, 0 and Voc (say it's 19V) and on the Y axis you plot the multiplication of amps times voltage, which we know to be power, you will find a curve with a peak. The MPPT seeks to operate your solar array at that peak. Without MPPT, the voltage is more a function of the battery's state of charge (from 11-13.8V) and the current that flows is on the graph of your panel's power function for a given voltage. In other words, without the dc/dc converter logic and MPPT smarts, the battery is a big tail that wags the dog (solar array) - I have a plot of the MPPT lines in my review of the 60W sunforce array - its located in the photos section and plots how the voltage reacts to the current, and where the maximum power point is - for those panels it's optimal for charging 12V lead acid batteries so MPPT controllers won't pay for themselves but the graph is interesting to understand Voc, Isc, and the curve in between.

If all this electrical stuff is getting confusing, lets change the example. Think of voltage (V) as RPM from your car's engine. Now think of Amperage (I) as being Torque on the crankshaft. Work done is RPM x Torque. If either is zero, no work is done. And just hooking the crankshaft to the differential doesn't give you alot of options, so we invented the transmission which allowed us to get the most work out of th e engine no matter the conditions. MPPT is just an automatic transmission - it finds the peak RPM and Torque for your conditions (accellerator pedal, slope, tire size, etc) and gets the most out of the engine (panels) for any operating point. For 12VDC systems, you don't alwyas need a transmission - just hooking the output of the panel (crankshaft) to the battery (differential) will work. Granted it's oversimplified but the idea is the same - you want to find the peak in the curve (in the sunforce 4 panel set I actually plotted the I vs V curve over the panel's entire operating range - its in the photographs for that product, the sunforce 50048 Sunforce 50048 60-Watt Solar Charging Kit look at the black photo - it's got pink and blue lines representing the voltage and current you can get from the panel. Think of the graph as an engine plot and it makes better sense but the analogy still isn't perfect, just close.

A 16V, 30 watt panel might give you 33 watts at a particular voltage, or an extra 10% using MPPT. In other installations, wiring your panels in series for higher voltages may be where the maximum power is found. The chip inside the MPPT tracker searches for this peak in your system and operates the solar panel (or array of panels) at it's absolute maximum power, which is sent to the DC/DC converter to charge your batteries.

We might get 10-30% more power doing this, but the voltage will be all wrong for charging our battery, or our battery array. And that's where the DC/DC converter steps in. As a simple example, say you find that 2 panels in parallel give you 14.5V at 1.9A going through your non-MPPT charge controller, or 27.5W delivered to your batteries. Wired in series using MPPT they give you 37V at 1.25A or ~48W. You would get more power by wiring in series for a higher solar voltage of 37V, which is too high to charge a 12V lead acid storage battery. Now you need a MPPT.

The MPPT takes the 37V, 1.25A from your panels and gets ~48W, looses 2W in conversion inefficiencies(give or take) for 46W out, and converts it to 13.6V to charge your battery array at 3.38A [45.96W] whereas had you wired the two panels in parallel you would get about 27.5 watts in this illustration.

MPPT systems are found in high voltage solar arrays (100V+) because the peak power points in these systems are up high in voltage and low in current. It has a second advantage - by running lower current through the panels, you can get by with smaller wire which lowers the project cost given the price of copper.

To sum it all up -

For really small solar panels, (1w) and big batteries (100 AH) you really don't need a charge controller just a diode to prevent backflow when the sun is down. Car battery mainters are made this way.

As you increase power and run the risk of overcharge, some controller is needed. The cheapest is like the one sold here - the non-mppt which works well with solar panels that are close to the battery voltage and would not optimize much with MPPT.

And finally as you cover your house with solar panels, MPPT systems sqeeze every last drop of power so long as you operate them within their specified parameters (often limits on voltage and current comming in or watts converted) Outback is a major MPPT converter which can handle a VERY wide range of input voltages and run a grid-tie system with or without batteries. As for 4 stars - you can buy MPPT trackers about this size for $112 now.

The Sunforce #60032 controller is a decent product at a reasonable price. Unfortunately, it doesn't include maximum power point tracking (MPPT) technology, so it wastes about 15-25% of the incoming power, especially at times of low solar input (which of course is when you need it most). To be fair, no charging controller that I know of in the under-$100 price range has MPPT, so I'm not knocking the #60032's value--just pointing out that if you're planning on spending the money for hundreds or thousands of watts of panels (like one recent reviewer), it probably makes sense to spend another hundred bucks and get an MPPT controller (e.g., Blue Sky or Heliotrope models) that can milk the maximum power from that expensive array... instead of throwing away part of it, as this unit does.

When I hocked this up I instantly started ruining some tests to see exactly how well it works and after some tweaks I can tell you I am very happy and recommend this to any one that wants to keep there battery's healthy.
This thing will automatically throttle up and down the current to any battery to keep the voltage exactly were it belongs. The only had 3 problems with mine.
1. The voltage meter was off by +.2 volts!
2. The amp meter was off by -600ma!
3. This is not a mppt controller and wastes about 1 amp in my set up but for the price that is not bad.
Both points 1 and 2 were easily fixed by tweaking 2 pot's inside that are very easy to get to.

Bought this controller from Amazon and really liked it at first. In fact I still like it but am having to return it.

The controller works great and is a lot better than the previous model I had on the solar panels.

Problem is that the voltage display on the unit is not working right. I have 3 80 watt GE solar panels hooked up to this controller. They put out about 22 vdc to the charge controller, which is then regulated by the controller going to the batteries at anywhere from 12-14 vdc.

Hooked the controller up and it was fine for the first hour or two. Then checked the voltage display and it was reading 20 vdc! If it was really at this level, it would overcharge my 12 volt batteries and ruin them very fast. Checked the actual output with a digital volt meter and it was actually at 13.7, which is normal. Tried a second meter and got the same reading.

End of the story is that the new controller works great, but the meter on the front of the unit that tells you what the meter is putting out to the batteries is defective 1-2 hours after being hooked up. Its going back and will be getting a better controller and hope it works better and for a longer time. Amazon was very easy to work with but hope that they get things like this fixed.

Item works, I expected a little better performance. Shows amperage of charge accurately when it is higher than 2.5 amps, at less then 2.5amp display goes to 0.1 and does not display lower currents, then starts weirdly to "pulse".
The built in Voltmeter is not too exact. It is important to know if battery bank has 12.8V or 12.5V since this reflects the percentage of its charge - 12.8V = close to 100%; 12.5 = 70%. The Voltmeter in the device I got is about 3% off ; about 0.3V to 0.4V - I never know till I do an exact measurement).
So basically it is o.k. if one is not looking for 99% accuracy. Nevertheless, for the money I spent, I thought I'd get little more.

This Solar Array -to- Battery Array charge controller has worked 24/7 continously for me for almost two years.
Yea it's not the most efficient set-up, however the status display is great and the Golfcart batteries do not complain.
Remember to put a 30A Slow-Blow fuse on the input.
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Update: Now I have two Sunforce 30A controllers in Parellel.
That's 60A from two different panel array into one battery bank.
Great for those cloudy days.

perfect product for my needs. I am using it to control my 500 watt solar
array. Works perfect, easy to install. Will purchase another when I expand
to 2000 watts.follow up: it failed after 8 or 9 days, amazon is replacing it free of charge, but this is something that cannot fail or my lights go out.

Charge Controller was easy to install and works as advertised. Much better product than the one I replaced. Very happy with it.

I purchased this along with an 80 watt solar panel. I went with this instead of the 7amp charge controller because I wanted to readout of volts and amps instead of just lights. So far I've been very happy with it. Charges the battery nicely and I don't have to worry about disconnecting it as it adjusts the amps to a minimal when the battery is full.

The only complaint I have with this is it did not come with a outlet socket that it talks about needing. I had to swing by NAPA to purchase one...not a huge deal but it would have been nice were it included.

All in all a nice controller and I'm ready if I step up to a 400 watt panel or add additional 80 watt panels.

Had product for 8 months and display stopped working, also voltage/current selection switch stopped working. Sorry to say company doesn't stand behind this product, has no US office, but wants me to mail both directions at my expense and they will only repair. Why repair a questionable product and who knows how long it would take for repair and return. This is an "off shore" company. Good news is Amazon is great, they are refunding after I return to them. I will buy a different vendor's controller from Amazon.