Pumping Water 11 feet up (and a few other small loads)

Surfpath

I'm helping a friend affected by Hurricane Beryl. His main need is to pump water from his under house tank 11 feet up to his kitchen - for the next month - until power comes back to his remote location. I'm thinking to keep it simple let's stick with no power inversion. Just keep it 12v, like an RV.

His desired loads are as follows:

• 11Amp 12v Flowjet pump at 40 minutes a day
• Two tablet device charging: 40watts for 3 hours per day
• Headlamp battery charging: 20 watts for 3 hours a day
• LED lights in the evening 24 watts for 3 hours a day

He has convenient access to Deka Golfcart FLA batteries 230 Amp hrs 6V. 
He also has easy access to this 100 watt semi flexible 12v panel:

Maximum Power Current (Impp):5.38A
Maximum Power Voltage (Vmpp): 18.69V
Open-circuit Voltage (Voc):21.89V
Short-circuit Current (Isc): 5.72A

I'm planning to get him a PWM controller rated for the number of panels needed.

My main questions I'd like a little help with are:

1. Will 2 of the Deka 6V batteries suffice?
2. How many of the 100w panels will he need?
3. What do you think about the pump for this application?

Again, this is a temporary set up until he is back on grid. His area was hit hard, and -for the next few weeks- access to other items is slightly limited. 

littleharbor2

Short answer... 2, or 3 panels, 2 batteries and a 20 or 30 amp PWM controller will more than cover his loads.

BB.

[note I have edited the solar panel sizing calculations by adding an 80% battery efficiency derating] after first post--Did not change the answer to 3 panels minimum]

And from me, the longer answer (I am genetically incapable of short answers, apparently):

• 11Amp 12v Flowjet pump at 40 minutes a day
• 11 amps * 12 volts * 2/3 hours per day = 88 Watt*Hours per day
• Two tablet device charging: 40watts for 3 hours per day
• 40 Watts * 3 hours per day = 120 WH per day
• Headlamp battery charging: https://pvwatts.nrel.gov/pvwatts.php20 watts for 3 hours a day
• 20 Watts * 3 hours per day = 60 WH per day
• LED lights in the evening 24 watts for 3 hours a day
• 24 Watts * 3 hours per day = 72 WH per day
• Total = 340 Watt*Hours per day

Battery bank minimum of 2 days of "no sun", to 50% discharge:
340 WH per day * 2 days *1/0.50 max discharge * 1/12 volt battery bank = 113 AH
2* Deka 6 volt batteries = 12 volts @ 230 AH (>>113 AH minimum suggested)

Say near Houston Texas, fixed array facing south, tilted 30 degrees from flat:
https://pvwatts.nrel.gov/pvwatts.php 


Can use 5.74 hours of average sun for August, or use 3.76 hours of sun for December (winter backup power). Two solar panel calculations, one based on sun, the other based on charging battery capacity:

230 AH * 14.78 volts charging * 1/0.77 solar panel+charger deratings * 0.05 rate of charge * 1/0.80 FLA battery efficiency  = 221 Watt array minimum (for FLA battery charging--emergency backup usage)
230 AH * 14.78 volts charging * 1/0.77 solar panel+charger deratings * 0.10 rate of charge = 441 Watt array nominal suggested for full time off grid

340 Watt*Hours of load * 1/0.77 solar+charger deratings * 1/3.76 hours of sun per day (winter) = 276 Watt array "December break even".
117 Watt array * 1/0.65 solar fudge factor for bad weather and such = 180 Watt array (for minimum backup Genset usage during poor weather)

Solar array suggested, at least 276 Watts and up to 441 Watts for a nice year round backup system.

He also has easy access to this 100 watt semi flexible 12v panel:

Or, around 3-5 solar panel array. A PWM charger sizing:

3 * 5.38 amps Imp * 1/0.80 PWM charger safety derating = 20 amp minimum derating for 3 panel array
5 * 5.38 amps Imp * 1/0.80 PWM derating = 34 Amp or ~40 Amp minimum deraring for 5 panel array

And for 3 or more panels in parallel, there should be a fuse or circuit breaker per solar panel string to reduce the chance of fire if a panel or solar wiring gets short circuited (like a rock through a panel, wire insulation eaten by small fuzzy animal, etc.).

Maximum Power Current (Impp):5.38A
Maximum Power Voltage (Vmpp): 18.69V
Open-circuit Voltage (Voc):21.89V
Short-circuit Current (Isc): 5.72A

For the water pump, either use an electrical switch (DC rated for 11+ Amps @ 12 volts) or a pressurized water storage tank to reduce pump cycling (if using faucet to turn off water).

https://www.amazon.com/rv-water-pressure-tank/s?k=rv+water+pressure+tank

I am not "thrilled" with semi-flexible solar panels if installed permanent outside--Prefer standard glass panels--But will work. Typically will only get a few years of panel life if mounted permanently in sun.

-Bill