I've been reading on here for a while but decided to create an account to post a question I've been thinking about for awhile.
I currently have a very small 24V system with 200W solar and 550wH of batteries. I'm using a Victron 100/20 MPPT and 500VA inverter. I'm building a house and moved in to a small part of it last winter with no electricity. After 5 months I bought and installed the above components and it's amazing how much easier life gets with a little bit of power and pressurized running water!
Anyways, next spring I would like to upgrade (if I can afford it) to a larger system which will run a fridge, kitchen appliances, well pump, etc. I plan to place a large water cistern above my house and pump into it on sunny days. I'm probably going to go with a 1/2hp or 3/4hp 3ph 240V well pump run from a VFD with 120V input because I don't want to set up a split phase system. I only want to run this pump when it's sunny outside. This is mainly a concern in the winter (Western Montana) because I don't get very many days with sun and I don't want to use batteries to pump water. I'm also up against the base of the mountains and lose some morning sun.
A couple options come to mind:
1) Use battery voltage/state of charge to control an input to the VFD to enable the pump. This would work but the pump would keep running after sunset until the battery was sufficiently depleted.
2) Same as 1 but add a timer so it can only run during the middle of the day. This has the same limitations though because if the battery is charged it will still pump even if not sunny.
3) Monitor the solar panel voltage and enable the pump when it is above a certain threshold. I understand that panel voltage varies with charge controller load but based on my observations, it seems that the more intense the sun, the higher the voltage.
4) Same as 3 but buy a tiny solar panel in the 5-10 VOC range and use it as an irradiance measurment device to control the pump circuit.
Has anyone tried this? Is it a dumb idea? Do you have any ideas on how you would actually implement this? I would also need a way to stabilize the output because I would like the pump to stay on for a minimum amount of time even if a cloud passes.
Thanks!
I currently have a very small 24V system with 200W solar and 550wH of batteries. I'm using a Victron 100/20 MPPT and 500VA inverter. I'm building a house and moved in to a small part of it last winter with no electricity. After 5 months I bought and installed the above components and it's amazing how much easier life gets with a little bit of power and pressurized running water!
Anyways, next spring I would like to upgrade (if I can afford it) to a larger system which will run a fridge, kitchen appliances, well pump, etc. I plan to place a large water cistern above my house and pump into it on sunny days. I'm probably going to go with a 1/2hp or 3/4hp 3ph 240V well pump run from a VFD with 120V input because I don't want to set up a split phase system. I only want to run this pump when it's sunny outside. This is mainly a concern in the winter (Western Montana) because I don't get very many days with sun and I don't want to use batteries to pump water. I'm also up against the base of the mountains and lose some morning sun.
A couple options come to mind:
1) Use battery voltage/state of charge to control an input to the VFD to enable the pump. This would work but the pump would keep running after sunset until the battery was sufficiently depleted.
2) Same as 1 but add a timer so it can only run during the middle of the day. This has the same limitations though because if the battery is charged it will still pump even if not sunny.
3) Monitor the solar panel voltage and enable the pump when it is above a certain threshold. I understand that panel voltage varies with charge controller load but based on my observations, it seems that the more intense the sun, the higher the voltage.
4) Same as 3 but buy a tiny solar panel in the 5-10 VOC range and use it as an irradiance measurment device to control the pump circuit.
Has anyone tried this? Is it a dumb idea? Do you have any ideas on how you would actually implement this? I would also need a way to stabilize the output because I would like the pump to stay on for a minimum amount of time even if a cloud passes.
Thanks!