If we look at a datasheet for a solar charge controller, we can find many different voltages.
- PV input voltage
- MPPT voltage range
- Minimum input voltage or start-up voltage
But what are they, and what do they mean?
This article aims to bring clarity to that.
MPPT Start-up Voltage
This is the voltage at which the MPPT will start working (120VDC in the example). If the voltage is under this voltage, the MPPT will not put power into the battery.
MPPT Voltage Range
For this example, the MPPT Voltage Range is 120V DC to 450V DC. While the max input voltage is 500VDC. So What doe MPPT voltage range mean?
When the voltage input to an MPPT charge controller falls outside its specified range of 120VDC to 450VDC, its efficiency and functionality are affected.
Below 120VDC, the controller may not effectively perform maximum power point tracking, leading to reduced energy harvesting efficiency, and it might not even activate if the voltage is below the startup threshold.
Above 450VDC, while still within the maximum input limit, the controller can operate but with decreased MPPT efficiency, potentially leading to suboptimal energy conversion. Consistently operating outside this optimal range can also stress the system, potentially reducing the lifespan of the charge controller.
Nominal DC Volt/Max DC voltage
Nominal means that the MPPT will be the most efficient at this voltage level (360VDC).
The maximum voltage will be 500VDC. If you exceed this voltage, the charge controller will be damaged.
Max input voltage = Voc * panels in series * 1.25
Why do we need the additional 1.25 safety factor?
Because a solar panel will measure more than the Voc on a sunny cold day.
If you didn’t include the safety factor, the charge controller will get damaged on a cold sunny day.
Do you want to know how to select an MPPT charge controller? Read my guide about it here.
FAQ
What is the minimum input voltage for MPPT solar charge controller?
The minimum input voltage should be at least 5 volts over your battery voltage OR the minimum specified in the manual.
If the voltage is not high enough, the charge controller will not start.
What is PV input voltage?
This is a voltage range where powerpoint tracking works the most efficiently.
I’m an off-grid enthusiast. I created this website to give clear and straight-to-the-point advice about solar power. I’m also the author of the book ‘Off-grid solar power simplified‘. Read more about me on my about page, check out my Youtube channel, or send me a message.
Yes Nick. I have a 200 AH lithium ion battery a 2000 watt converter and a 100 amp controller. My friend and I hooked all this up yesterday. And we’re running off of four 25 Watt solar panels last night It ran my big seventy inch t v with no problem and then today it kept shutting itself off and just a little while ago The whole system shut down there is no read out on the MPPT controller. The battery or the converter I had planned to add more batteries. That’s why I got a 100 amp. MPPT controller should I have got a smaller one until I get more batteries? 4/24/2023 8:30 ÇMT
If I understand correctly, you have a total of 100W solar panels? The ideal current of your inverter and charge controller will draw that load. So you don’t have enough solar panels to power your loads. Your battery is empty. i recommend getting a battery monitor (shunt).
Hi there I’m interested in solar products special solar charger controller, inverter and batteries
Hello Jean, I recommend to start reading my beginners guide to off-grid solar here. Good luck!
Hi Nick, As a rookie to all this solar world, I am learning so much from your wonderful channel.
I made a start earlier this year with a Renogy100 watt panel a 12 volt Solarflex 130 Ah deep cycle leisure battery and a EpEver Mppt 20 Amp Triron 22 controller. I have since tried to move on with another 12volt leisure battery with the aim of going for a 24volt system. I have also purchased two ET Elite Plus 430 W Bifacial half-cut-panels, I have not yet made a start with my new panels but if I have things right and run the new panels in parallel I will only just be in-side the limits of my 20 Amp controller. I will certainly require a 24 volt inverter as right now all I have is a 12 volt. I have my mind set on an all in one controller, the one that appeals to me and within my price range, being an EDECOA EM-402 A which has a mppt voltage range of 55 – 450 Vdc. When I ordered my first 430 W panel I also ordered an all in one controller only to be put straight and getting informed I would need at least 5 panels to reach the start up voltage. Thing is Edecoa are not showing the start-up voltage for their unit, so should it fall within the 55 – 450 Vdc? My panels spec show an NOCT of 36.77 open circuit Voltage, which will give me 73.54 volts in series. I will certainly appreciate your advice.
Pippa Wilkins
Never heard of the brand EDECOA. But generally if they have an input range of 450Voc, then optimal MPPT range should be somewhere at 230VDC. I cannot find any information about them. However, if you want a hybrid inverter, and are on a budget i recommend taking a look at growatt.