Permit Question

mach66

Hello group, I am new here.. I have a question about permits.  I am installing a one 100 W panel system with one battery.  I live in Northern AZ, someone told me that as long as a solar setup is on  a trailer, it doesn't require a permit.. Is this true? and If so what is the definition of trailer?

Photowhit

It is all local laws. It's likely, if you are not connecting to the grid. A battery based system, and a small one, likely won't need any permit... a solar lawn light is a solar panel and battery running a light... I hope you don't need a permit for one!

mach66

Thank You for the reply, it will be in a greenhouse running a few small booster pumps.

Raj174

Hi mach66,
Be sure to get the right size battery for your 100 watt panel. A 12 volt 25 to 30 amp hour sealed or AGM battery with a 7 to 10 amp PWM charge controller should work fine. If you had in mind a bigger battery then you'll need more panel watts to charge it.

mach66

thanks for that tip, I was definitely looking at a larger battery, but have not purchased one yet.  the controller I believe is 30 amp.  I have a 5,000 W inverter (actuality two of them.) If I wanted to expand the system, then I guess I would need more panels and a larger capacity controller?

Raj174

Keep in mind that larger inverters usually self consume more power than smaller ones. It may only be 15 or 20 watts per hour more but it adds up over time and has an impact on battery and charging needs, so inverter losses need to be considered when determining battery size necessary to meet the loads and the amount of panel wattage needed to charge the battery. 

mach66

thanks again for the info... Good to know, I have smaller inverters as well.. So if I understand this right, if I have a 2 amp pump running 24 hours a day, and I have a 30 amp battery, then that would mean that the 100W panel would run the pump, but then there would be almost nothing going to the battery during the day right? just did some research. The pump is 24 watts.. so if my system is putting out approximately 300 - 500 watts per day, I guess that means that the pump would only be using half or less of that during day light hours right? Or if my panel is 100 watts per hour, then I am only using 25% of that during peak sunlight hours... So to answer my own question I guess almost half the power would go to the battery so it would take 2 days to fully charge the battery if starting from 0 charge correct?   So if I went with 200 Watts of panel, I should be covered I am guessing.. That seems like an awful lot just to run a tiny booster pump hahha.
OH yeah, I also read that figuring controller power is a 10% reduction in the math as well, is that right? so I guess I also need to figure 5% for the inverter too?  so about 15%  besides my pump draw.. is this sounding like I am getting it right?
Any help here would be greatly appreciated...

BB.

Me--Math--boring, but I always give it a shot:

• 2 amps * 12 volts * 24 hours = 576 Watt*Hours per day load
• 2 amps * 24 hours * 2 days storage * 1/0.50 max discharge = 192 Amp*Hour @ 12 volt battery recommended (off grid design rules)

Charging a battery bank should be between 5% and 13% rate of charge:

• 192 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.05 rate of charge = 181 Watt array minimum (seasonal/weekend)
  
• 192 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.10 rate of charge = 362 Watt array nominal (full time off grid)
  
• 192 AH * 14.5 volts charging * 1/0.77 panel+controller derating * 0.13 rate of charge = 470 Watt array "cost effective" maximum
  

And based on hours of sun per day, nearish to St. George, Utah, fixed array, nominal panel angle:

http://solarelectricityhandbook.com/solar-irradiance.html

Saint George
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 53° angle from Vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
4.34	4.65	5.96	6.36	6.49	6.64
Jul	Aug	Sep	Oct	Nov	Dec
6.20	6.12	6.17	5.81	4.82	4.32

Pick February as "break even month" (you can pick different):

• 576 Watt*Hour per day load * 1/0.61 DC system eff * 1/4.65 hours a day sun = 203 Watt array minimum (break even Feb)
  

So, for full time pumping, I would suggest a 362 Watt minimum array (you need to both charge the battery bank and supply the pump at the same time).

-Bill

Raj174

And you can use the 30 amp charge controller with the setup Bill described, and it's sized to give you a couple of days power in case of bad weather. Thank you Bill

mach66

Bill (my deceased father's name!) you are one awesome person! Thank you very much for that post... Just what I needed to rest assured!  It's more panel than I was hoping for though.. That is only one pump, soon, we will be running 2 and keep expanding up to 10 pumps! I am glad we have AC in the green house hahahha... These pumps have to run 24/7 as we are doing aeroponics and my veggies can't go more than an hour or two without the water... this is why I have decided to go solar.  This particular system is designed to be expanded to 400 Watts, but I am sure that is due to the controller.. This is going to be way more expensive than I thought.. I hope we sell a lot of veggies so we can expand with the solar,,,, Thank you both Bill and Raj174, you have both been very helpful!

mach66

Just to clarify, that means I need at least a 200 Amp Hour battery, or a bank up to 200 AH correct?

WaterWheel

Correct assuming a 2 day reserve which you want for cloudy days.