strikehammer
New Member
I was given the 8 solar panels after they were removed from a roof needing replaced. They are 245 w units about 13 years old with a 25 year lifetime. I mounted them on a frame that can be tilted to get optimal sun angle. Obviously I need to upgrade to a 48v inverter as my 12v unit only uses one battery. I did test it by adding my 3 lifepo4 golf cart batteries to make a 48v system
My other problem is that the inverter starts dropping the 120 vac below 110 v when battery voltage drops below 10.9 v with a 400 w load. It starts beeping below 11 v but does not cut off until 10.5 v leaving vac near 90 v which is unacceptable. Lifepo4 batteries cutoff at 10v.
What I need help with is finding a 48 v inverter that has a cutoff before dropping ac voltage below 110 vac. as I have an auto transfer switch that will switch to grid power to maintain the 400 w load. Also, the cut on voltage needs to be about a half volt higher so the batteries can maintain load when the sun comes up and begins recharging them and the transfer switch turns back on.
Does anyone know of an inverter than has adjustable voltage cut on & cut off settings? Either that or I need some sort of separate switch to do that. This has to be an automatic process as some days will produce much less than the power required.
I have a constant load of 400w for 16 hrs. (9 am to 1 am daily) for a total of 6.4 kwhs. The battery capacity is 1280 wh per for 5120 which should more than cover the hours that the panels produce less than 400w. At mid day, I am measuring about 32 amps at 48 v into the solar charger or about 1500w. That lasts for about 3 hrs. then starts dropping off per the solar curve. I am getting about 3 more killowatt hours before & after peak sun for about 7 or 8 kwh total on a clear day which is more than the total load I believe. Please advise if my calculations are not accurate.
I look forward to any input or ideas to make this work. It is my first project.
My other problem is that the inverter starts dropping the 120 vac below 110 v when battery voltage drops below 10.9 v with a 400 w load. It starts beeping below 11 v but does not cut off until 10.5 v leaving vac near 90 v which is unacceptable. Lifepo4 batteries cutoff at 10v.
What I need help with is finding a 48 v inverter that has a cutoff before dropping ac voltage below 110 vac. as I have an auto transfer switch that will switch to grid power to maintain the 400 w load. Also, the cut on voltage needs to be about a half volt higher so the batteries can maintain load when the sun comes up and begins recharging them and the transfer switch turns back on.
Does anyone know of an inverter than has adjustable voltage cut on & cut off settings? Either that or I need some sort of separate switch to do that. This has to be an automatic process as some days will produce much less than the power required.
I have a constant load of 400w for 16 hrs. (9 am to 1 am daily) for a total of 6.4 kwhs. The battery capacity is 1280 wh per for 5120 which should more than cover the hours that the panels produce less than 400w. At mid day, I am measuring about 32 amps at 48 v into the solar charger or about 1500w. That lasts for about 3 hrs. then starts dropping off per the solar curve. I am getting about 3 more killowatt hours before & after peak sun for about 7 or 8 kwh total on a clear day which is more than the total load I believe. Please advise if my calculations are not accurate.
I look forward to any input or ideas to make this work. It is my first project.
