Some background first, actual question at the bottom:

Last year December my area in the Philippines was directly hit by a super typhoon, international name: Typhoon Rai.

For three weeks after that happened, we basically had no electricity. That means no phone/laptop charging if we didn't go to malls that had generators. There were other serious problems that came with that calamity, but for this post I'm only focusing on basic usb charging.

Three days after that typhoon, a local solar panel supplier reopened business and yes, all the solar charge controllers were out of stock because it was in extreme demand. For the same price I had the choice between two 150watt (21Voc) panels and a 400w (49Voc) solar panel. I went with the 150 watt panels because I luckily started messing around with Arduino months before and had several usb buck converters on hand that could handle up to 24volts. I didn't have any 12v batteries or solar charge controllers at the time so it was the best I could do and that choice did put my family in a more comfortable spot compared to most other people in the area.

I also had the usual bunch of electronics components that come with the Arduino hobby, such as capacitors, diodes, transistors and the like - but they didn't see much use at the time. I didn't have any buck converter that could handle 50v and if I did I wouldn't be asking this question haha.

The actual question:

If I went with the 400W (49Voc) solar panel, would I have been be able to use it for usb charging?

• apparently we can't just connect two usb buck converters in series (I don't understand why)
• I had a small kit of 1/4 watt resistors at the time, would connecting those in parallel, then connecting that to usb buck converters in series work fine even if inefficient?
• other possible ideas that might be feasible for an Arduino hobbyist - without proper solar charge controllers

I'm mainly asking so if someone I know ends up in a similar situation I might be able to provide some help even when directly sending electronic components can't be an option. (I now have a proper off-grid solar setup for future emergencies)

Some background first, actual question at the bottom:

Last year December my area in the Philippines was directly hit by a super typhoon, international name: Typhoon Rai.

For three weeks after that happened, we basically had no electricity. That means no phone/laptop charging if we didn't go to malls that had generators. There were other serious problems that came with that calamity, but for this post I'm only focusing on basic USB charging.

Three days after that typhoon, a local solar panel supplier reopened business and yes, all the solar charge controllers were out of stock because it was in extreme demand. For the same price I had the choice between two 150 watt (21 Voc) panels and a 400 W (49 Voc) solar panel. I went with the 150 watt panels because I luckily started messing around with Arduino months before and had several usb buck converters on hand that could handle up to 24volts. I didn't have any 12 V batteries or solar charge controllers at the time so it was the best I could do and that choice did put my family in a more comfortable spot compared to most other people in the area.

I also had the usual bunch of electronics components that come with the Arduino hobby, such as capacitors, diodes, transistors and the like - but they didn't see much use at the time. I didn't have any buck converter that could handle 50 V and if I did I wouldn't be asking this question, haha.

The actual question:

If I went with the 400 W (49 Voc) solar panel, would I have been be able to use it for USB charging?

• apparently we can't just connect two USB buck converters in series. (I don't understand why.)
• I had a small kit of 1/4 watt resistors at the time, would connecting those in parallel, then connecting that to USB buck converters in series work fine even if inefficient?
• Other possible ideas that might be feasible for an Arduino hobbyist? - Without proper solar charge controllers?

I'm mainly asking so if someone I know ends up in a similar situation I might be able to provide some help even when directly sending electronic components can't be an option. (I now have a proper off-grid solar setup for future emergencies.)

Some background first, actual question at the bottom:

Last year December my area in the Philippines was directly hit by a super typhoon, international name: Typhoon Rai.

For three weeks after that happened, we basically had no electricity. That means no phone/laptop charging if we didn't go to malls that had generators. There were other serious problems that came with that calamity, but for this post I'm only focusing on basic usb charging.

Three days after that typhoon, a local solar panel supplier reopened business and yes, all the solar charge controllers were out of stock because it was in extreme demand. For the same price I had the choice between two 150watt (21Voc) panels and a 400w (49Voc) solar panel. I went with the 150 watt panels because I luckily started messing around with Arduino months before and had several usb buck converters on hand that could handle up to 24volts. I didn't have any 12v batteries or solar charge controllers at the time so it was the best I could do and that choice did put my family in a more comfortable spot compared to most other people in the area.

I also had the usual bunch of electronics components that come with the Arduino hobby, such as capacitors, diodes, transistors and the like - but they didn't see much use at the time.

The actual question:

If I went with the 400W (49Voc) solar panel, would I have been be able to use it for usb charging?

• apparently we can't just connect two usb buck converters in series (I don't understand why)
• I had a small kit of 1/4 watt resistors at the time, would connecting those in parallel, then connecting that to usb buck converters in series work fine even if inefficient?
• other possible ideas that might be feasible for an Arduino hobbyist - without proper solar charge controllers

I'm mainly asking so if someone I know ends up in a similar situation I might be able to provide some help even when directly sending electronic components can't be an option. (I now have a proper off-grid solar setup for future emergencies)

Some background first, actual question at the bottom:

Last year December my area in the Philippines was directly hit by a super typhoon, international name: Typhoon Rai.

For three weeks after that happened, we basically had no electricity. That means no phone/laptop charging if we didn't go to malls that had generators. There were other serious problems that came with that calamity, but for this post I'm only focusing on basic usb charging.

Three days after that typhoon, a local solar panel supplier reopened business and yes, all the solar charge controllers were out of stock because it was in extreme demand. For the same price I had the choice between two 150watt (21Voc) panels and a 400w (49Voc) solar panel. I went with the 150 watt panels because I luckily started messing around with Arduino months before and had several usb buck converters on hand that could handle up to 24volts. I didn't have any 12v batteries or solar charge controllers at the time so it was the best I could do and that choice did put my family in a more comfortable spot compared to most other people in the area.

I also had the usual bunch of electronics components that come with the Arduino hobby, such as capacitors, diodes, transistors and the like - but they didn't see much use at the time. I didn't have any buck converter that could handle 50v and if I did I wouldn't be asking this question haha.

The actual question:

If I went with the 400W (49Voc) solar panel, would I have been be able to use it for usb charging?

• apparently we can't just connect two usb buck converters in series (I don't understand why)
• I had a small kit of 1/4 watt resistors at the time, would connecting those in parallel, then connecting that to usb buck converters in series work fine even if inefficient?
• other possible ideas that might be feasible for an Arduino hobbyist - without proper solar charge controllers

I'm mainly asking so if someone I know ends up in a similar situation I might be able to provide some help even when directly sending electronic components can't be an option. (I now have a proper off-grid solar setup for future emergencies)