OH Dear me...Please help

Re: OH Dear me...Please help

moerboer wrote: »

Pump
380 watt 220 ac set to 2 Bar pressure
3 x 200 watt 12 volt panels
2 x 150 AH deep cycle batteries
30 Amp controller
2000 watt cont power and 4000 watt peak power

Are you saying you are still trying to get it working?

First, the 200 Watt solar panels... What is the Vmp/Imp (voltage maximum power/current maximum power) of your panels... 200 Watt "12 volt panels" (typically Vmp~18 volts) are pretty rare these days (at least in the US/North America).

Next, the 2x 150 AH deep cycle batteries... Are these 12 volt batteries, two in parallel, for a 12 volt @ 300 AH battery bank? If so, the rough power you can get from such a battery bank:

• 12 volts * 300 AH * 0.85 inverter eff * 1/20 hour rate = 153 Watts average long term discharge (optimum AC power)
• 12 volts * 300 AH * 0.85 inverter eff * 1/8 hour rate = 382.5 Watt average long term discharge
• 12 volts * 300 AH * 0.85 inverter eff * 1/5 hour rate = 612 Watt maximum continuous power (pretty hard on the batteries)
• 12 volts * 300 AH * 0.85 inverter eff * 1/2.5 hour rate = 1,224 Watt maximum surge power (seconds to minutes draw)

Using Solar Electric Handbook, we can estimate the amount of sun you will receive for a 600 Watt array (note, software bug, use "facing south" for array, even though you would face it north as you are south of the equator):

Windhoek
Average Solar Insolation figures

Measured in kWh/m²/day onto a solar panel set at a 67° angle (from vertical):
(For best year-round performance)

Jan
Feb
Mar
Apr
May
Jun


6.26
6.17
6.34
6.33
6.62
6.29


Jul
Aug
Sep
Oct
Nov
Dec


6.34
7.04
7.17
6.70
6.57
7.36


Assuming this is near where you live/similar climate, you have lots of sun there (and not much rain?):

• 600 Watt array * 0.52 off grid system efficiency * 6.26 hours minimum average sun per day = 1,953 Watt*Hours per winter day

Your 380 Watt motor may draw upwards of 5x 380w = 1,900 Watts starting

And, depending on how your motor is rated (i.e., 380 Watts output power may draw upwards of 760 Watts input--worst case), you could expect it to run:

• 1,900 WH per day * 0.85 AC inverter eff * 1/760 Watts running load = 2.125 Hours per day minimum run time (on a sunny day)

For average loads, you should only expect to run ~66% to 75% of average power every day (leave a little bit left over for bad weather, optional loads, etc.).

Your battery bank may be a bit on the small size, and the AC inverter may be way over-sized--The maximum practial AC inverter that your present battery bank would support will be around 600-800 Watts or so. A 2 kWatt inverter would "kill" the battery bank if operated at full power at night. The motor is right on the ragged edge of running on your battery bank.

Assuming the batteries are in good shape and the solar array is charging OK:

600 Watts * 0.77 panel+controller derating * 1/14.5 amps = 32 Amps "typical" maximum charging current. Your 30 amp PWM charge controller may be too small for your 600 Watt array--PWM controllers do not take well to being "over paneled" (too much current, charge controller may shut down/get overheated/damaged).

Lastly, look at your wiring from the battery bank to the AC inverter--Assuming 1,900 Watts of starting power (yours may be lower starting power):

• 1,900 Watts * 1/0.85 inverter eff * 1/10.5 volts inverter cutoff = 181 Amps of worst case 12 VDC starting current

So--you need to check the wiring on your battery bank... It needs to be short/heavy copper cables from the batteries to the AC inverter. Too long of cable, too small of diameter, and the resistance will cause too much voltage drop from the battery bank (if you assume 11.5 volt battery under load, and 10.5 volt inverter, you can only have 1 volt drop).

Your actual starting current is probably less than 181 amps--But it sounds like (if you hare having problems) either the battery bank is not capable of supplying the starting current for the motor and/or your wiring has too much voltage drop (by the way, review this website for "proper" battery wiring).

We would also need to learn more about your water pumping needs and setup... A 380 Watt water pump is quite a bit of power for a domestic water system (sink, shower, etc.). You might be better off looking at a 12 volt (or 24 volt) DC pump (typically used in Recreational Vehicles/Caravans/etc.). Do you have a pressure tank to store up water pressure from the pump?

Note that the links provided are to our host in the US--And examples of classes of products you may want to think about using... Understand that you should purchase locally to ensure you get good support from local vendors.

Does this help?

-Bill