Any DC power supply will do to provide power, if that's what you are afterHi, can you share what worked for your solar panel simulation?
Any DC power supply will do to provide power, if that's what you are afterHi, can you share what worked for your solar panel simulation?
I tried DC power supplies with constant current (CC) and voltage control but i cant get the voltage to go higher than 29V without the current exceeding the transformer's max current. The MPPT controller is sinking current too much that I cant control with the CC varistor.Any DC power supply will do to provide power, if that's what you are after
If you short out the panel, the current will still flow up to the Is spec of the panel. PV panel is the current limited source.Keep in mind that most controllers are expecting a "voltage source" from a panel, and not a "current source" from a power supply - and may affect your overall design if this was going commercial for safety reasons.
In simplistic terms, the difference is this:
1) For a current-source, such as a battery or power supply - if you drop a wrench on the output terminal for a direct short, the current will max out and the wrench will vaporize. Battery / Supply may let out the magic smoke.
2) For a voltage source, such as a solar panel, if you drop a wrench on the output of the panel terminals, all current flow will simply stop. The cells in the panel don't care - they don't feel shorted or care. Power just simply stops.
In the very old days of SCC's - typically the hysteresis ones prior to pwm, some controllers would repetetively short the panel output leads during the later stages of charging. Some scc's would open one side instead of short, but the effect is the same.
Just saying - it may or may not be a consideration. Perhaps you will design to allow both sources in the internal fusing / safety of the SCC. Or just put a sticker on it saying "no power supplies allowed, panels only!"
This I can understand, a shorted fully illuminated panel will have Isc flowing through it, there is no or little voltage at its shorted output connectors. So there is no usable power from the panel.If you dead short a solar panel you'll get Isc or whatever the max is with the current solar conditions, BUT it will make very little voltage doing this, and Watts will be amps X volts where volts are just above zero. So.. very little power.
I have run multiple PWM SCCs off of multiple PSUs. It is absolutely workable.
Clearly you don’t understand voltage and current sourcedsKeep in mind that most controllers are expecting a "voltage source" from a panel, and not a "current source" from a power supply - and may affect your overall design if this was going commercial for safety reasons.
In simplistic terms, the difference is this:
1) For a current-source, such as a battery or power supply - if you drop a wrench on the output terminal for a direct short, the current will max out and the wrench will vaporize. Battery / Supply may let out the magic smoke.
2) For a voltage source, such as a solar panel, if you drop a wrench on the output of the panel terminals, all current flow will simply stop. The cells in the panel don't care - they don't feel shorted or care. Power just simply stops.
In the very old days of SCC's - typically the hysteresis ones prior to pwm, some controllers would repetetively short the panel output leads during the later stages of charging. Some scc's would open one side instead of short, but the effect is the same.
Just saying - it may or may not be a consideration. Perhaps you will design to allow both sources in the internal fusing / safety of the SCC. Or just put a sticker on it saying "no power supplies allowed, panels only!"
Because you would only have light when there was light? ?
As far as the difference in shorting behavior from a battery to a solar panel, I think it basically comes down to batteries being orders of magnitude larger as a current source by weight and surface area than a solar panel. For example, a car battery and a ~300w panel might both weigh 30ish lbs, but while the solar panel has a ton of surface area and creates heat dispersely across that wide area, the battery has very little surface area for its weight but can put about 100 times more current into heating it when short circuited. Figuring most 30lb car batteries will at least do over 800amps into a short. Thats if its heating itself, BUT a car battery is far more likely to heat the thing you short it with as well.
So consider that in simple terms, volts drop against resistance. Voltage also drops proportionally to resistance. This means the voltage drop across a fixed resistance will change if that resistance’s proportion of the total circuit resistance changes. This is what is causing the ‘terminal voltage’ reading to differ so much between a panel and a battery when shorted. A solar panel as a current source has a relatively high resistance. If its own internal resistance is only 1% of the total circuit, you will 99% of all the volts on the outside terminals. However, if you lower the resistance of the rest of the circuit by so much that the panel’s internal resistance represents 99% of the total resistance, only 1% of its voltage will be present on the outside terminals, because the rest is dropping internally and converting to heat in the panel.
Again a 100w battery and. 100w PV panel have the same potential power output. Again you need to understand the Fundamental differences between real world voltage sources and real world current sources. This exposing the characteristics.Watts of heat on the wrench you used to short the thing would be terminal voltage times amps(Isc), which would be fairy low because the volts are in the low tenths. Anything times zero is zero, and since volts here are almost zero, so are watts of heat in the wrench.
On a battery the internal resistance is extremely low compared to the solar panel, so hooking the same resistance of ‘short circuit’ to it would result in far more voltage being dropped across that resistance, and less inside the battery itself because it represented a smaller proportion of total resistance. While i have shorted solar panels and seen voltage well below 1v, I would guess that a ‘shorted’ car battery (with a wrench for example) would probably be putting out 4-7 volts at the terminals. This is extrapolated based on what ive seen load testing batteries at their rated cranking amps level. Since watts of heat in the wrench would be volts times amps, the car battery would put more heat into the wrench (and less heat into itself) even at the SAME current level as the solar panel. But… in reality it will probably be 100 times more current, or more. So ~10x higher terminal voltage to drop across the wrench, times 100x the current, is an absurd Watt number that can heat the wrench EXTREMELY quickly. Funny thing is, even then there is less heat being generated outside the battery (in the wrench) than there is inside the battery where the majority of volts are dropping. It ‘s only because the thermal mass of a battery is so much higher than the wrench we’re shorting it with, that we notice the wrench heating so much faster. The wrench will melt all the way to open circuit before the battery even gets hot enough to boil its water.