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MPPT solar battery charging backgrounds
MPPT performs better in conditions when it’s needed the most;
- When the battery is discharged
- During cloudy, dusty or smoggy days
- During partial shading of the panels
Conditions where solar panels perform worse:
- When panel temperature is high
- When solar panel is partial shaded
- When solar panel angulation towards the sun is off
Rsadeika wrote: »
Not sure who to believe, the snippet above was taken from an article that states, up to a 30% improvement with mppt. Another article I read, Wikipedia, states up to a 20%% improvement with mppt. It seems like this is something relatively new, and there just might be a lot of anecdotal coverage, using charts and interpretations.
Getting away from theory and making a real application, how would somebody determine a 20%-30% improvement? This mornings conditions, heavy overcast with drizzle, the reading at the solar panel - 8.66V, battery reading - 12.54V, only load is from the PWM unit, and possibly the three DC-DC regulators that I have attached . So, I change out my PWM unit for an MPPT unit, what is my improved solar panel usage rate?
Tracy Allen wrote: »
I'll add another instance to the possible confusion. There is also MPPC, Maximum Power Point Control. That is the control strategy of solar battery charger chips like the LTC3652. (I use that in my own systems.)
In contrast to MPPT (T=tracking), it does not attempt to track the maximum power point. It is pre-set at a typical maximum power point for the solar panel specs, and it subsequently prevents the output from collapsing below that point. This works pretty well even compared with MPPT, because the MPP for a solar panel does not vary all that much from low to high sunlight conditions.
Rsadeika wrote: »
Not sure how many people are following this thread, that do not have a solar system setup, and are just reading this just to kill time. My interpretation of some things that I have observed.
On occasion I post some numbers like solar panel V and battery V, these numbers taken in a general context probably do not give to much insight. For instance, my solar panel, rated at 50W, when I first received it, I did some measurements, as a stand alone unit. This was quite interesting, my impression was, that when it was getting some light it would be outputting a steady output rate. Well, that is not a correct assumption, the voltage rate, as measured with a volt meter, is all over the place. Even when the sun looks like it is directly shinning on it, you may have fluctuations between 16V and maybe 18V. When it is dealing with a partly cloudy day, it gets even more interesting, fluctuations, in a fraction of a second, could drop as low as 12V, or less. In other words your solar panel is putting out a very fluctuating pattern.
When I had my mini RadioShack solar panel setup, I had the solar panel system output connected directly to some rechargeable batteries. First I did a measurement of what the panel system was putting out, in this case, I think the panel rating was 9V, it was showing maybe 11V. Now, the key point, when I attached the batteries to the system, if the panel output was 11V, with the batteries attached the panel measurement was now down to maybe 9V, depending on the battery charge state. Now how do you make any sense out of that, or even try to do some meaningful data capture?
I am sort of glad I am not doing a scientific study paper on this, I would be at a complete loss as to how to even get some meaningful readings let alone a good meaningful explanation of the data. Maybe I should put on my scientist hat, and start reporting unbiased findings.
Renogy 50W 12V Monocrystalline Solar Panel
Output Cables: 4.0 mm2 (0.006 in2), 600mm (23.6 in) Connectors: MC4 Connectors
Maximum Power: 50W Maximum System Voltage: 600V DC (UL)
Optimum Operating Voltage (Vmp): 18.5V Open-Circuit Voltage (Voc): 22.7V
Optimum Operating Current (Imp): 2.7A Short-Circuit Current (Isc): 2.84A
Dimensions: 24.8 X 21.3 X 1.2 In Weight: 9.9lbs
Rsadeika wrote: »
Not sure how many people are following this thread, that do not have a solar system setup, and are just reading this just to kill time. My interpretation of some things that I have observed........
Feb 25, 2017
WiFi Solar Station
#define reboot() __builtin_propeller_clkset(0x80)
volatile float vx,vy;
int event, id, handle;
// Add startup code here.
wifi_start(31, 30, 115200, WX_ALL_COM);
solarId = wifi_listen(HTTP, "/solar");
batteryId = wifi_listen(HTTP, "/battery");
// Add main loop code here.
wifi_poll(&event, &id, &handle);
if(event == 'P')
else if(event == 'G')
if(id == solarId)
wifi_print(GET, handle, "%.2f\r", vx);
if(id == batteryId)
wifi_print(GET, handle, "%.2f\r", vy); // Send to html
print("%cSolar panel: %.2f",HOME,vx); // Show on local terminal
print(" Batteries: %.2f%c\n",vy,CLREOL); // Show on local terminal
adc_init(21, 20, 19, 18);
v0 = adc_volts(0); // Solar panel
vx = (v0*4.9295);
//vx = v0;
//print("%cSolar panel: %.2f",HOME,vx);
v1 = adc_volts(1); // Battery array
vy = (v1*4.7869);
//vy = v1;
//print(" Batteries: %.2f%c\n",vy,CLREOL);
<!-- wifisolar.html -->
<font face="Arial" size=6 color="red">
Solar Station Report
<font face="Arial" size= 2 color="cyan">
Voltage for Solar Panel
or Battery Array
<!--<input type="radio" name="choices" onclick="getFromMcuS();"> Solar -->
<!--<input type="radio" name="choices" onclick="getFromMcuB();"> Battery -->
var val = document.getElementById("value");
val.innerHTML = "Value: " + response + " V";
function httpGet(path, callback)
var req = new XMLHttpRequest();
req.open("GET", path, true);
req.onreadystatechange = function()
if (req.readyState == 4)
if(req.status == 200)