Author Topic: Solar system advice needed  (Read 404 times)

ProGeek

Solar system advice needed
« on: May 12, 2020, 05:40:30 PM »
I've got 2 of the Sanity Solar 255W panels. Specs below. I need recommendations on how to set them up. Should I wire them in series or parallel? Two panels is either 31V or 62V max.  Should I consider nominal 24V or 48V input for the charge controller? Is it better to use a 12V/24V/48V battery bank with these panels considering the input voltage into the charge controller? I want to minimize power loss, max efficiency, and minimize voltage conversion. Then there is the inverter that is dependent on the battery bank voltage. I'm looking at 1750-200W inverters. I have a Xantrex 1750W 12V Modified Sine Wave Inverter, but I want a pure sine wave. My Grundfos 10 SQ05-160 115V soft start well pump draws 12 amps and I was told I should use a pure wave inverter. They recommend a 1200-1800W inverter generator to run it. I'm leaning toward making everything 24V, but 12V a big appeal. How much power loss will I see using a 12V battery bank rather than a 24V? This is a somewhat low budget project but I don't want to use crap either. Looking for recommendations for the charge controller and inverter (pure sine wave). I'd like to spend $700 or less for both components.

Pmax 255w
Current at Maximum Power (Impp) 8.22A
Short Circuit Current (Isc) 8.83A
Pmax (imp) 8.5A
Pmax (Vmp) 9.09A
Voltage at Maximum Power (Vmpp) 31.0V
Voltage (Voc) 37.4V - 38.3V
If the freedom of speech is taken away then dumb and silent we may be led, like sheep to the slaughter.

RWS

Re: Solar system advice needed
« Reply #1 on: May 14, 2020, 04:07:54 PM »
How much power loss will I see using a 12V battery bank rather than a 24V? This is a somewhat low budget project but I don't want to use crap either.
How much battery will you need?  How much shade will you be able to tolerate?  Like cloudy rainy days.
 You can run 2ea 12 v batteries in series (24v) and double your battery capacity.  Batteries in parallel limit is 2 except the new li-ion.

ProGeek

Re: Solar system advice needed
« Reply #2 on: May 18, 2020, 06:19:35 PM »
I figure if it's not overcast, the panels will charge a battery bank enough to run the pump 12A 115V for about 3 hours throughout the day. At best the panels will make 2140wh @ 24V or 89ah. My math may be way off depending on conversion of the 12A load and 24V battery bank. My well doesn't recover quickly and at 4G per minute. So I'll have to run the pump for about 15 minutes every hour to refill the tank. To answer your questions: 1. Running 11am and 4pm total 1.5 run time, so maybe 400ah of battery bank to even out load? 2. It's mostly for irrigation, so rain or cloud cover reduces the need for water. 3. I have four 6 year old 12V 125ah batteries of questionable capacity. They seem to hold a 13+V charge. I was going to start with them, but will probably get eight 6V 180ah golf cart batteries later. I'm having difficulty converting the 115V load from the inverter to the panel output and what the best charge controller and inverter would be.
If the freedom of speech is taken away then dumb and silent we may be led, like sheep to the slaughter.

RWS

Re: Solar system advice needed
« Reply #3 on: May 18, 2020, 06:53:24 PM »
Really and truly if all you are going to run is a remote water pump say for livestock or garden and no electronics, digital display, ect., then a modified sine wave inverter is all you will need.  If on the other hand there will be any electronic control then a sine wave inverter will be required.

2 panels 8.5 amp you will need a 20amp charge controller about $60.00.  If you later decide to add 2 more panels then just buy a second charge controller.  You can run 5 in parallel.  Charge controllers are a commodity now.  Shop for what looks good to you.
https://www.morningstarcorp.com/products/sunsaver/    This is what I use for small stuff.  It is potted and blind, no display.  Usually beginners like a display to see what is happening, just more money.  Don't buy directly from Morningstar corp.  Shop internet and save.

ProGeek

Re: Solar system advice needed
« Reply #4 on: May 30, 2020, 01:50:30 PM »
What about the panel 30V max input / 24V input to the charge controller with a 12V battery bank? I'd need 12V for my current inverter. Am I going to see a lot of power loss from that?
If the freedom of speech is taken away then dumb and silent we may be led, like sheep to the slaughter.

RWS

Re: Solar system advice needed
« Reply #5 on: May 30, 2020, 04:05:58 PM »
What about the panel 30V max input / 24V input to the charge controller with a 12V battery bank? I'd need 12V for my current inverter. Am I going to see a lot of power loss from that?
Well,  Most solar panels have anywhere from 34 to 38 vdc at max power.  So the charge controller is incompatible right away.  Try an find a model that has a higher input voltage.  60Vdc used to be a standard so I am sure some are available.
At 12 Volts wire size will be large and distance between battery and inverter will be small.