POWER SHUT DOWNS

System

I have installed a solar system to provide lights on my poultry farm in the village.
The Pv panel is 40 watts
Controller is 12 amps.
Battery is 105 amp/hr 12v.(deep cycle)
Inverter is 500 watts.

The farm is wired as normal with a fused box.
The light bulbs (energy saver types) total 156 watt.

When first installed, I used a brand new ordinary automobile 12v battery with a 300 watt inverter. The system lasted for 6 hours and shut down.
The shut downs continued daily until I changed the inverter to 500 watt. I was adviced to use a deep cycle battery which is what I use at present.
The shut down still occurs, this time the inverter becomes very hot.
Any advice please?

Skamey


Sorry, I forgot to specify that this farm is in Ghana, in Africa where there are abandant sunshine per day and in a 240 volt zone.
.

crewzer

Re: POWER SHUT DOWNS

The Pv panel is 40 watts… Battery is 105 amp/hr 12v.(deep cycle)… The light bulbs (energy saver types) total 156 watt… The shut down still occurs, this time the inverter becomes very hot…. Any advice please?

Skamey,

This won’t work at all. There are at least two fundamental problems.

Assuming your lights are on for 12 hours/night, your daily energy requirement is 156 W x 12 hours = 1872 Whr. Your battery’s energy content is 12 V x 105 Ah (at 20 hr discharge) = 1260 Wh. You should be able to see where this is going.

Assuming the inverter is ~90% efficient, the 156 W of lamps is pulling 156 W / 90% = 173 W from the battery bank. At 12 V nominal, 173 W / 12 V = ~14.4 A. Assuming the battery is healthy and fully charged, the lamp load will completely drain the battery down to 10.5 V in ~ 6 hours.

To run 156 W of lamps for ~12 hours, you’ll theoretically need a battery rated at 210 Ah. However, allowing for three days of autonomy and not discharging the battery below 50% state of charge, you’ll need 210 Ah x 3 / 50% = 1,260 Ah.

Or, you can stay with the present battery and reduce your lamp load down to 156 W / ~12 = 13 W. To do so, you may have to consider LED lights. See: http://www.superbrightleds.com/MR16_specs.htm

Assuming the equivalent of 5 hours / average day of “full” Sun and ~60% overall system efficiency, the PV array will generate ~40 W x 5 hours x 60% = ~120 Whr / day. That won’t run the lamps for even one hour. Staying with the 156 W load, you’ll need an array rated at ~625 W.

Assuming proper ventilation, there’s no reason why a quality 500 W inverter should overheat while handling a 156 W load.

The LED solution might be worth serious consideration. My ~20 outdoor LED lights are powered by a 40 W PV module, a single 12 V x 105 Ah deep-cycle battery, and this controller: http://www.morningstarcorp.com/products/SunLight/index.shtml

HTH,
Jim / crewzer

System2

Re: POWER SHUT DOWNS

Thank you for yuor advice.
Your suggestion of the Led lights is very convincing is being given a serious thought.
Should I double the battery to 210ah and retain the 40watt pv panel toghether with some of the led lights, will the problem improve?
I have another 40 watt pv panel indoors. What about double the panel wattage to 80?

skamey

mike95490

Re: POWER SHUT DOWNS

skofib wrote:

What about double the panel wattage to 80?

That will only recharge the battery faster. It won't last any longer at night.
If you add more batteries, you WILL need to add more panels.

Also, consider some of the Compact Fluorescent bulbs, not as expensive as LED's, but much less power than Incandescent bulbs.

Going with LED's means you can likely run off 12VDC

Do you need Spot light, Simulate Daylight to grow Chickens faster, Flood Light, or just enough light to see to walk at night?

crewzer

Re: POWER SHUT DOWNS

Skamey,

Assuming 5 hours or "full" Sun per average day, the 40 W PV module should be able to supply the energy required to run 10 W of 12 V LED lamps for ~12 hours. Adding another 40 W module in parallel to the first would allow you to increase the load to ~20 W for ~12 hours per night.

An additional 105 Ah battery would help in the winter (cold battery = less capacity), but you probably wouldn't notice any difference in the summer.

Note that you need to confirm your local insolation. If, for example, there's only 4 hours of "full" Sun in the Winter, then, even with two 40 W modules, you'll need to reduce your load from ~20 W x 12 hours to ~16 W x 12 hours.

See: http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/sum2/state.html

HTH,
Jim / crewzer

mike95490

Re: POWER SHUT DOWNS

skofib wrote:

I am Interested in the spot lights. I use inverter to generate 240v electricity. Will the spot lights be suitable. Yes I need these to grow my chickens faster.
What is the cost?

Cost is in the link to the vendor:
See: http://www.superbrightleds.com/MR16_specs.htm

If you get the 12V LED lights, you won't need the inverter, and can save 10 or 20% from not having inverter losses
I don't know how much light chickens need, but the LED bulb catalog has data for how many lumens the bulbs put out

Try looking at all the messages in this topic
http://www.wind-sun.com/smf/index.php?topic=1392
too, you may find something helpful there.

System2

Re: POWER SHUT DOWNS

So far, except for special relatively low light requirements, I'm not impressed with any of the LED lights. I'm sure that with time things will change, but so far, with anything I've seen, overall light output from the LED lights, watt for watt, doesn't even come close to CF lights. Yes, they use very little power, but they also give very little light and temperatures above 23C really shortens their life unless you dim them down..
Wayne

Roderick

Re: POWER SHUT DOWNS

Other people have already covered the battery capacity and panel output, and there's nothing for me to add. I don't know how much money you have to buy more equipment, but hope you do. Using compact fluorescent lights is also a very good idea, probably the first thing to do.

I wonder if your inverter is overheating? If it's the kind that is meant to be used in a car, it's probably not intended to be running for long periods, day after day. Also (pardon my ignorance) does it get very hot where you are in Ghana? Maybe the inverter needs shade and airflow?

crewzer

Re: POWER SHUT DOWNS

Skamey,

I received your e-mail message. I think we have too may “what ifs” floating around. Here’s baseline calculation from which you should be able to scale a solution to your needs.

Assumptions:

Worst case insolation in Ghana: 4.5 hours of “full” sun per average day
(see: http://www.apricus.com/html/insolation_levels_africa.htm )
PV module operating efficiency: 88%
Wiring efficiency: 97%
Controller efficiency: 95%
Battery efficiency (Wh out / Wh in): 80%
No inverter (DC lights)
Design autonomy: 3 days no sunshine
Maximum Battery discharge: 50%

Baseline load: 100 W for 12 hours

The energy required to power 100 W of lights for 12 hours = 100 W x 12 hours = 1.2 kWh (net).
Battery capacity to sustain 1.2 kWh for three nights and not drop below 50% SOC = 1.2 kWh / day x 3 days / 50% = 7.2 kWh.
Using 12 V batteries, 7.2 kWh of capacity = 7.2 kWh / 12 V = 600 Ah, or ~ 6 of the 105 Ah batteries connected in parallel.

At 80% battery efficiency, 1.2 kWh/day out requires 1.5 kWh/day in.
At 95% controller efficiency, 1.5 kWh/day out requires 1.58 kWh/day in.
At 97% wiring efficiency, 1.58 kWh/day out requires 1.63 kWh/day in.
At 88% PV module operating efficiency, 1.63 kWh/day out requires an array rated to generate 1.85 kWh/day.
At 4.5 hours/day of full sun, 1.85 kWh/day would require an array rated for at least 411 W (STC).

Adding an inverter with an operating efficiency of 88% would require increasing both the array size and the battery bank size by ~14%

You can scale the sizes above for different load sizes. For example, a 156 W load would require increasing the sizes of the array and the battery bank by 1.56. A 20 W system would require a system only 20% as large as the baseline.

Some of the LED lamps here will operate from 240 VAC: http://www.superbrightleds.com/edison.html If you decide to go with LED lamps, I’d strongly recommend using 12 V models. This would remove the inverter, its inefficiency and its operating problems from your system.

HTH,
Jim / crewzer

niel

Re: POWER SHUT DOWNS

i'm going to throw an obvious variable here into this. this is the starting point of crewzer's calculations for the need of 12hrs of on time for the lights. if the operating times for those lights could be made less, this would lessen your needs greatly through either conservation or just not needing the light at that time (like possibly going to bed at that time?). crewzer is making a worst case scenario with the 12hr operating times to make sure that your needs are covered. being so close to the equator there aren't seasonal time periods of perpetual darkness as the poles would experience making lighting needed there for very long times. if your need for the light is 8hrs per day for example, this represents a 1/3 power reduction, which is significant. that would reduce all of the other requirements by the same, straight on down the line for you wouldn't then need as much battery capacity or pv capacity and would reduce costs significantly. lessening the power requirements further by intermixing some leds to be used in minimal lighting areas could also save you lots of power consumption thereby reducing your needs for solar equipment. the leds are great night lights, but their light outputs are generally small to match their power consumptions.
skofib, you are the variable in this as it is your needs that govern the rest of the setup. it does have to be a balanced system so that all parts compliment each other for the best efficiency of operation based on your needs. what this means is you don't want to unercharge or overcharge your batteries that in turn you don't want to underpower or overpower your lights (backup power excesses being the exception as you want a reserve). crewzer laid it out and this you can scale somewhat to your needs limited by manufacturing constraints such as available capacity.