African Orphanage Solar Needs for an Aeroponic System

[Learjet]

Greetings!

This is my first post on the forum and I've combed through quite a few threads looking for an answer to the dilemma that I'm trying to solve. Since this is a very crucial issue the only thing that 'I know' is that I 'don't know enough' which is why I need expert advice to get this right the first time, thanks for your patience.

I design custom aeroponics systems for clients that usually have access to 110V outlets however, some friends of mine are missionaries that run orphanages in a few well know garbage dumps in Kenya. My goal is to send them a few aeroponics units so that they can feed the kids and sell the remaining produce to generate an income for their charities. It's surprising how little goes a very long way there.

While lighting for their systems will not be a problem because they have ample sunlight, running the pump for the units is where I need help designing a system that will work via solar panels.

The system works with a timer that runs the pump for 1 minute on, and 4 minutes off, it's a 12V DC, 100W pump that outputs 160PSI to run the system. The timer that I normally use is 110V and so I'm in a dilemma where I'm not sure if I should even go to 110V AC, or find a timer that will work on a 12V DC system?

Additionally, I'm not sure how many batteries and panels that I will need to run this simple system. As you might image we're trying to do this as economically as possible.

If you would be so kind, I can imagine that a few of you have similar systems that do pretty much the same thing and I would appreciate your wisdom on the matter, many thanks!

Peace,
EJ

[Sunking]

Easy peazy. For 600 watt hours per day:

Panel Wattage = 300 watts. Depending on if you use Grid Tied or Battery cost = $300+ for GT panels, and up to $1000 for battery panels
12-Volt Battery = 250 AH, $300 - $400 every 3 years whether you like it or not.
MPPT Charge Controller 25 Amps minimum, $300

[Learjet]

Epic! Thanks so much!

If you would be so kind, would this infrastructure enable me to expand easily? For example, adding an additional system?

Once I get things moving I'll post some pictures in use, really looking forward to seeing it in use over there and I know that the kids will enjoy the learning experience.

Thanks again!

Respectfully,
EJ

[Sunking]

There are some things you can do. First is forget the number 12 as the number 12 has no purpose in solar. What I am driving at 12 volt system are extremely limited to 1000 watts. Really not even that much.

You are going to want to do a few things.

Select a very common panel wattage from a manufacture that has been around a long time. If you have never heard of them, pass. You want names like Panasonic, Kyrocera, LG, GE, Sanyo. 200 watt 60-cell panels.

Avoid Prime Number of panels except 1 and 3. You want to be able to connect as many panels in series that you can. With Prime Numbers you only have two options. All in Parallel or all in series. Charge controllers have a Maximum Input Voltage which limits the number of panels you can put in series. 3 to 4 max in series.

Bite the bullet now and buy a 80 Amp MPPT Controller with at least a 150 Voc input voltage. A 80 Amp MPPT Controller has the following maximum Input Power limits based on battery voltage. Just accept the fact a good 80 Amp MPPT Controller is going to cost $600. Stick with Midnite Solar, Morniingstar, and Outback.

1000 watts @ 12 volts
2000 wattts @ 24 volts
4000 watts @ 48 volts.

Did I say forget the number 12? Use either 24 or 48 volts. DO NOT USE !2 VOLTS

Additionally DO NOT parallel batteries. If you need say 400 AH use 400 AH batteries. A 400 AH battery is 4 or 6 volts. For a 24 volt system using 6 volt batteries requires 4 batteries wired in series.

Keep your voltage loses between Panels>Controller, Controller > Battery, and Battery > Load Equipment like an Inverter or Pump to 2% or less voltage drop. That generally means using much larger wire.

Run as many panels in series as your controller will allow.

[Learjet]

"Keep your voltage loses between Panels>Controller, Controller > Battery, and Battery > Load Equipment like an Inverter or Pump to 2% or less voltage drop. That generally means using much larger wire."

Awesome, I can put this 6 gauge solid copper ground wire that I'm been hauling around for 20 years to use. My wife asks me every time that we move "Are you ever going to actually USE this?" I think it's about 250' of it, very heavy to move around.

Thanks again!

Respectfully,
EJ

[Sunking]

"Awesome, I can put this 6 gauge solid copper ground wire that I'm been hauling around for 20 years to use.

Don't count on that EJ as 6 AWG could be on the small size. Higher the voltage, means lower current and smaller wire.

The problem with low voltage is the current required for a given power level. This is exactly why utilities use such high voltage up to 1 million volts. Example lets say 1000 watts.

12 volts is 84 amps. That takes a 6 AWG and only good out to 5 feet. Greater than 5 feet is going to be much larger wire.
24 volts is 42 amps, much smaller wire.
48 volts is 21 amps, even smaller wire.

See the problem with 12 now? So the challenge if you plan to grow is you gotta think ahead and over size certain components so they do not have to be replaced. If 300 watts were the max, then 12 volts would be fine. But once you go over 500 panel watts you should be looking at 24 or 48 volts.