In the LT thread, someone asked about the new "External Solar Port" option. Pasting that response here as well. I'll try to get some more details/images of the external plug and location of the second Victron solar controller.
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Great new option that STC is making available in both the HT and LT is the "External Solar Port" option. The HT that I used for four days in February, didn't have the option so I still haven't seen it first hand. All I know is the "External Solar Port" option, as they call it, adds a second Victron 100/20 Solar Controller, an external connector and dedicated wiring. That system is completely separate, with no shared wiring or components, with the rooftop solar panels, wiring, and that Victron 100/20 Solar Controller. Totally redundant system and since they are not shared, no clamping of voltage or amps like when different spec panels are plugged into, and share, one solar controller. I'll be investigating what connector they use, where they place it, and where the second solar controller is installed in the electronics cabinet.
Background for those new to solar panels and controllers:
Being able to point portable panels directly at the sun increases output dramatically and will allow you to harvest power a lot closer to the rating of the panel compared to panels laying flat on a rooftop. You can park your camper in the shade, which also shades blocks roof-top solar array, but still place portable array out in the sun.
Like any solar controller, users need to be very careful not to exceed the voltage of the controller. That is considered by camper manufactures when sizing camper solar arrays and so there is no risk of the the user exceeding the controller limits. But offering a portable solar panel port, the camper and solar controller manufacturers are relying on the user to not exceed the controllers max voltage.
Limiting solar array voltage, to below the controllers max voltage, is important. Controllers don't like excessive voltage. The controller amperage is the max output amperage; not the max input.
In this case, the solar controller is a 100/20 so 100v max input and 20amp max output. For our 12v lithium batteries, we calculate with our approximate battery charge voltage which is 14.5v. 14.5v x 20amps is 290watt output from this solar controller and that 290watts match the Victron literature. Note the 20amp output is the same for 12v, 24v or 48v. We are 12v so only get 290watt max output, but the same controller will push up to 580watts to a 24v battery/system or 1,160watts to a 48v battery/system.
All solar panels have various voltage and amp ratings. The two voltage ratings are:
Voltage at Open Circuit (VOC) is the maximum voltage a solar panel can output when there is no load connected to it (no current flowing).
Voltage at Maximum Power (VMP), is the voltage at which a solar panel produces its peak or optimum power level. That will increase as temperature decreases so in extreme cold, voltage can climb quite a bit. That is why VOC is used to calculate max voltage.
For the solar array sizes we are likely to use as portable panels, it would be uncommon to exceed the max voltage of this solar controller. Any single portable panel is of no risk. If multiple panels are used, most users wire them in series since wiring in parallel uses more connectors and isn't as easy/tidy. But it would take quite a few panels wired in series to exceed 100v.
Wiring in series, you add up the panel voltage, but amps stays the same.
Wiring in parallel, you add up the panel amps, but voltage stays the same.
My imaginary portable panel is 200watts with VOC of 20v, VMP of 18v and amps of 11amps. We use VOC when calculating to ensure we stay below solar controller max voltage.
2 in series = 40v/11amps
4 in series = 80v/11amps
2 in parallel = 20v/22amps
4 in series = 20v/44amps
All arrays voltage stay well below the 100v max input voltage of a Victron 100/20. So you'd really have to start adding up panels in series to go over voltage, but something to be aware of since we don't have the advantage of the manufacturer controlling the panel size for a give solar controller. If someone goes out and lines up seven 20v VOC solar panels in series and the resulting 140v voltage fries the 100v solar controller, that is user error and no manufacturer will cover that under warranty.
As for amps and wattage, as mentioned, the max output of this controller is 20amps which is 290watts (14.5v x 20amps) for 12v nominal systems. Any array sized with higher watts than the controller can use, in perfect conditions, is is considered "over paneled". Meaning, any solar array sized over 290watts will ever only see 290watts of throughput on this particular controller. It doesn't matter if array is 400 watts or 4,000watts. There are times when overpaneling is prudent because typically you never get 100% efficiency from your solar array (when panels are hot, it's partly cloudy, sun is low in the horizon in the morning, evening or winter, etc.).
Solar panels are so economical now, might as well over panel a bit. True that in perfect conditions, you won't use all the power your array can generate, but in less than ideal conditions, a larger array will make more power than a smaller array. Overpaneling lets you harvest more power, in less than ideal conditions, than an array sized exactly the same as your solar controller.
-----------------------------
Great new option that STC is making available in both the HT and LT is the "External Solar Port" option. The HT that I used for four days in February, didn't have the option so I still haven't seen it first hand. All I know is the "External Solar Port" option, as they call it, adds a second Victron 100/20 Solar Controller, an external connector and dedicated wiring. That system is completely separate, with no shared wiring or components, with the rooftop solar panels, wiring, and that Victron 100/20 Solar Controller. Totally redundant system and since they are not shared, no clamping of voltage or amps like when different spec panels are plugged into, and share, one solar controller. I'll be investigating what connector they use, where they place it, and where the second solar controller is installed in the electronics cabinet.
Background for those new to solar panels and controllers:
Being able to point portable panels directly at the sun increases output dramatically and will allow you to harvest power a lot closer to the rating of the panel compared to panels laying flat on a rooftop. You can park your camper in the shade, which also shades blocks roof-top solar array, but still place portable array out in the sun.
Like any solar controller, users need to be very careful not to exceed the voltage of the controller. That is considered by camper manufactures when sizing camper solar arrays and so there is no risk of the the user exceeding the controller limits. But offering a portable solar panel port, the camper and solar controller manufacturers are relying on the user to not exceed the controllers max voltage.
Limiting solar array voltage, to below the controllers max voltage, is important. Controllers don't like excessive voltage. The controller amperage is the max output amperage; not the max input.
In this case, the solar controller is a 100/20 so 100v max input and 20amp max output. For our 12v lithium batteries, we calculate with our approximate battery charge voltage which is 14.5v. 14.5v x 20amps is 290watt output from this solar controller and that 290watts match the Victron literature. Note the 20amp output is the same for 12v, 24v or 48v. We are 12v so only get 290watt max output, but the same controller will push up to 580watts to a 24v battery/system or 1,160watts to a 48v battery/system.
All solar panels have various voltage and amp ratings. The two voltage ratings are:
Voltage at Open Circuit (VOC) is the maximum voltage a solar panel can output when there is no load connected to it (no current flowing).
Voltage at Maximum Power (VMP), is the voltage at which a solar panel produces its peak or optimum power level. That will increase as temperature decreases so in extreme cold, voltage can climb quite a bit. That is why VOC is used to calculate max voltage.
For the solar array sizes we are likely to use as portable panels, it would be uncommon to exceed the max voltage of this solar controller. Any single portable panel is of no risk. If multiple panels are used, most users wire them in series since wiring in parallel uses more connectors and isn't as easy/tidy. But it would take quite a few panels wired in series to exceed 100v.
Wiring in series, you add up the panel voltage, but amps stays the same.
Wiring in parallel, you add up the panel amps, but voltage stays the same.
My imaginary portable panel is 200watts with VOC of 20v, VMP of 18v and amps of 11amps. We use VOC when calculating to ensure we stay below solar controller max voltage.
2 in series = 40v/11amps
4 in series = 80v/11amps
2 in parallel = 20v/22amps
4 in series = 20v/44amps
All arrays voltage stay well below the 100v max input voltage of a Victron 100/20. So you'd really have to start adding up panels in series to go over voltage, but something to be aware of since we don't have the advantage of the manufacturer controlling the panel size for a give solar controller. If someone goes out and lines up seven 20v VOC solar panels in series and the resulting 140v voltage fries the 100v solar controller, that is user error and no manufacturer will cover that under warranty.
As for amps and wattage, as mentioned, the max output of this controller is 20amps which is 290watts (14.5v x 20amps) for 12v nominal systems. Any array sized with higher watts than the controller can use, in perfect conditions, is is considered "over paneled". Meaning, any solar array sized over 290watts will ever only see 290watts of throughput on this particular controller. It doesn't matter if array is 400 watts or 4,000watts. There are times when overpaneling is prudent because typically you never get 100% efficiency from your solar array (when panels are hot, it's partly cloudy, sun is low in the horizon in the morning, evening or winter, etc.).
Solar panels are so economical now, might as well over panel a bit. True that in perfect conditions, you won't use all the power your array can generate, but in less than ideal conditions, a larger array will make more power than a smaller array. Overpaneling lets you harvest more power, in less than ideal conditions, than an array sized exactly the same as your solar controller.