What do I need for greenhouse Lighting

[Clifford]

I want to extend the growing season and start vegetables early in a 12x12 green house. I have 3 240w 24v panels for 720 watts, a small pwm charge controller, 4 large deep cycle batteries, and a 2600w power inverter. I want to power 1 medium sized fan, and at least 3 florescent light fixtures with 2 tubes each. The fixtures should be using 68 watts each per hour and the fan less than 10watts per hour. By my calculations this should be pulling 1400 to 1500 watts or just 2 hours of peak power of the panels. So far the system has failed to run the lights for the 6 hours I want and the fan 24 hours. What am I missing here? I have been considering converting to a DC system any ideas?

[Sunking]

Couple of questions.
'
How many hours each day do you want to run the light and fans.
What is you rlocation.
What time of year do you intend to use the system
Do the light fixtures use 68 watts per fixture, or is that total for all fixtures.

[Sunking]

OK I assume each fixture uses 68 watts and you have 3 of them you want to run 6 hours so 3 x 68 watts x 6 hours = 1224 watt-hours.
1 fan 10 watts x 24 hours = 240 watt hours
Total consumed = 1464, so lets just say 1500 watt-hours per day.

You said earlier you have 24 volt panels using PWM controller raises big RED FLAGS. Exactly what voltage are these panels. Need to know Vmp and Imp of the panels and how you have them wired. Another RED FLAG is the batteries. Minimum requirement is:

12 volts 650 Amp Hours
or
24 volts 325 Amp Hours

I know from you rfirst post you are not even close to the battery capacity you need. I suspect you have the whole system mis-configured

Right off the top of my head guessing location and time of year use you need:

Panel Wattage = 600 watts with MPPT Controller, or 750 watts with PWM controller.
Battery = 12 volt 650 Amp Hour, or 24 volt 325 Amp Hour
Charge controller = 60 amp @ 12 volt, or 30 amp 24 volt
Inverter = 400 watt.

[Clifford]

The panels are 240 watt 24 volt and are combined to make 24v output I think 21 amps. the battries are serial parrel connections for a total of 24volts and 420 amp hours (each battery is 12v 210 amp hour) each fixture has 2 34 watt bulbs. Thank you for the help.

[Sunking]

The panels are 240 watt 24 volt and are combined to make 24v output I think 21 amps.

That is not what we need. Panel specs Vmp and Imp. If they are 24 volt 240 watt battery panel should have Vmp of roughly 36 volts and Imp of 6.6 amps. The panels should be 72 cells and all panels wired in parallel.

Panel Make and Model?

[Clifford]

The panels are sharp N U - U24 0 F 1 240w 7.98a. VPM is 30.1 IMP is 7.98 Here is the data sheet http://www.amerescosolar.com/sites/d.../nu-u240f1.pdf I have 3 of these connected to a cheap PWM charge ontroller rated at 30a, The inverter is a Power bright ML 2300-24 and the battery bank is 4x Energizer e29hm rated at 210 min reserve capacity I hope this helps and thank you for your help.

[Naptown]

OK first problem is you are using grid tie 60 cell panels
If connected in parallel there is not enough voltage to charge a 24V battery
If connected in series you are wasting almost all of your wattage
first thing to do is to get a good MPPT controller like a Morningstar MPPT 45 and connect your panels in series.
more to come

[Clifford]

Ok so my charge controller is the issue. I see the Morningstar is good up to 48v if I connect my 3 three 24v panels in series that will put me at 72v. if I keep them in parallel that will not let me generate proper voltage for a 24 volt battery system right? So if I have the panels at 24v I need a 12 battery system and I would need a new inverter? Is the inverter even a good idea? or could I go 12v output for lights ect?

[Sunking]

The panels are sharp N U - U24 0 F 1 240w 7.98a. VPM is 30.1 IMP is 7.98

Right there is your problem, coupled with your charge controller. Since you have 3 panels, you are forced to wire them in parallel. The panel voltage is too low at 30 volts, it takes 36 volts.

To fix this at a minimum is you will have to buy a MPPT Charge Controller that can have a Voc input of 150 volts like a Morningstar TriStar MPPT 45 amp controller. Wire all three panels in series, and you are fixed up.

[Sunking]

Ok so my charge controller is the issue. I see the Morningstar is good up to 48v if I connect my 3 three 24v panels in series that will put me at 72v. if I keep them in parallel that will not let me generate proper voltage for a 24 volt battery system right? So if I have the panels at 24v I need a 12 battery system and I would need a new inverter? Is the inverter even a good idea? or could I go 12v output for lights ect?

No if you switch to 12 volts with a PWM controller you will turn your 240 watt panels into 100 watt panels.

If you use PWM controllers you have to use panels made for battery systems. Battery panels are 36 cells with a Vmp of 18 volts. You have Grid Tied panels which requires a MPPT controller. Use a MPPT controller and your charge current will jump up to 30 amps.

[Clifford]

Ok thanks so with a mppt controller and the panels in parallel making 24v 23a max the mppt controller is boost the voltage drop the amperage and charge the 24v bank> I will then have a 24v 420 reserve capacity bank providing plenty of power for my lights fan and perhaps a bit more. Now I just need to save some money.

[Sunking]

Ok thanks so with a mppt controller and the panels in parallel making 24v 23a max the mppt controller is boost the voltage drop the amperage and charge the 24v bank> I will then have a 24v 420 reserve capacity bank providing plenty of power for my lights fan and perhaps a bit more. Now I just need to save some money.

No sir, you have to reconfigure the panel in series so at the input of the controller will be roughly 90 volts @ 8 amps. On the output roughly 27 volts @ 30 amps.

[Clifford]

Thanks I understand need the higher voltage to push the charge on the battery's then the 4 deep cycles at 24v and 420 rc should be fine.

[Sunking]

Thanks I understand need the higher voltage to push the charge on the battery's then the 4 deep cycles at 24v and 420 rc should be fine.

Based on the info you provided, but I do have some doubts.

My concern has to do with the lights, and inverter, and to some degree the fan. I know you said the lights are 34 watts each, but I suspect when ran through the inverter losses maybe considerably higher. Also suspect the fan might use more than you think.

You have a huge inverter for such a small load. Inverters do not reach their peak efficiency until they reach maximum power output and you are far from that. My fear is even through the calculated load with all 6 lights and fan is 215 watts, with poor inverter efficiency may be pulling 300 watts from the batteries..

Do you have the means to measure the DC current between the batteries and inverter? If so measure it will all your toys turned on. Then determine how many watts you are pulling off the battery. So for example you measure the current and see 10.8 amps and voltage the battery is 26 volts then 10.8 amps x 26 volts = 281 watts. That could be a problem

Last concern is your location and time of year use. Location means everything with respect to panel wattage.

[Clifford]

I have a good multi meter and could measure Amps when things are up and running. I am in East Texas.