Please tell me where I have gone wrong...thanks!

[Peter Evans]

If anyone cares to help me double check my math and reasoning on usage I would super appreciate it (not just regular appreciate it):

I am about to install this setup and hope someone can prove something wrong with my thinking, otherwise I will have to go ahead and do the labor to mount everything.

I have three independent inverters, all off-grid (load reduction/stability), each drawing no more than 30 amps at 240 volts so around 6800 watts as an upper limit (each rated 10Kw) or 136 amps across each of three busses from the paralleled batteries. The fourteen 5 Kw batteries will be limited to 50 amps out each battery (@ 50 volts) so 35 Kw potential but an actual maximum of 6800 watts x 3 inverters = 21 Kw maximum.

Nominally the estimation nightime draw is 6800 watts for 10 mins per hour (A/C or heat) and 3000 watts additional nominal (utilities) with 30-120 minutes of 6000 watts once a night (car charging) so 15800 watts (15.8 Kw) at nominal peak for short periods from the 70 Kwh stored available.

The power company says the most I have ever used is ~3000 Kwh/month so ~100 Kwh/day with 4 to 5 hours coming from the (40) 450 watt panels delivering a realistic 10,000 watts/hr of their 18,000 watt rating in full sun.

I have estimated this 10,000 watt minimum output based 450 watt rating minus CMLF of 10% = 405 watts minus off angle of 10% = 364.5 watts minus 10% for dust = 328 watts minus 10% for inverter inefficiency =295 watts minus 5% for voltage drop (actual is .25%) = 265.5 watts rounded down to 250 watts/panel.

My goal is to operate year round with this setup without having to do a lot of juggling power by, say, choosing when to charge an electric vehicle. It is full sun 92% of the time where I live and at 60% of my estimate of solar output I will still be able to run everything nominally directly off the panels of those five hours. Do I need more battery capacity?

Thanks in advance

 

[sunshine_eggo]

See link #1 in my signature and model your array for your location with the array's tilt and orientation with PVWatts. It will yield monthly AC kWh generation numbers, and it also factors in your local weather averaged over the last 30 years.

You should be able to match up your monthly production numbers with your monthly consumption numbers.

 

[RV10flyer]

If anyone cares to help me double check my math and reasoning on usage I would super appreciate it (not just regular appreciate it):

I am about to install this setup and hope someone can prove something wrong with my thinking, otherwise I will have to go ahead and do the labor to mount everything.

I have three independent inverters, all off-grid (load reduction/stability), each drawing no more than 30 amps at 240 volts so around 6800 watts as an upper limit (each rated 10Kw) or 136 amps across each of three busses from the paralleled batteries. The fourteen 5 Kw batteries will be limited to 50 amps out each battery (@ 50 volts) so 35 Kw potential but an actual maximum of 6800 watts x 3 inverters = 21 Kw maximum.

Nominally the estimation nightime draw is 6800 watts for 10 mins per hour (A/C or heat) and 3000 watts additional nominal (utilities) with 30-120 minutes of 6000 watts once a night (car charging) so 15800 watts (15.8 Kw) at nominal peak for short periods from the 70 Kwh stored available.

The power company says the most I have ever used is ~3000 Kwh/month so ~100 Kwh/day with 4 to 5 hours coming from the (40) 450 watt panels delivering a realistic 10,000 watts/hr of their 18,000 watt rating in full sun.

I have estimated this 10,000 watt minimum output based 450 watt rating minus CMLF of 10% = 405 watts minus off angle of 10% = 364.5 watts minus 10% for dust = 328 watts minus 10% for inverter inefficiency =295 watts minus 5% for voltage drop (actual is .25%) = 265.5 watts rounded down to 250 watts/panel.

My goal is to operate year round with this setup without having to do a lot of juggling power by, say, choosing when to charge an electric vehicle. It is full sun 92% of the time where I live and at 60% of my estimate of solar output I will still be able to run everything nominally directly off the panels of those five hours. Do I need more battery capacity?

Thanks in advance

You just skipped the 400W beginner system and went all out. ? 52kWpv, 210kWh of LFP will be about right for us this year. We use between 40-80kWh daily. Once you get the system going, you’ll know what you need more of.

 

[Peter Evans]

You just skipped the 400W beginner system and went all out. ? 52kWpv, 210kWh of LFP will be about right for us this year. We use between 40-80kWh daily. Once you get the system going, you’ll know what you need more of.

I did stick three panels at 200 watts each with three tiny 20 amp chargers (pre-MPPT) two years ago to charge a battery an run a 2000 watt inverter in my trailer. Two years later working perfectly so I figured I might as well save $6000/year on utility and gasoline costs. It was a big jump so I figured I would see if my math is right. At peak they never get more than 180 watts (old style panels) out of 600 "claimed". From what I have been reading on the forum they are a lot better now.