Need Info On A Small Solar System

MIDGAPATRIOT

I'm wanting to put together a small solar system. I need to power a well pump, the well is 110' deep. The water would go into a storage tank. I also want to power a refrigerator/freezer, just a normal one like you have in your kitchen. What do I need? How many panels, inverter, batteries, and so forth. I know NOTHING about any of this so any info is GREATLY appreciated. Thanks in advance!!!!

BB.

Re: Need Info On A Small Solar System

In general, solar off-grid power is very expensive... So to limit the costs of over design (and undersign failures)--You really first need to know your daily power needs (by season).

Basically, if your power system can run on ~3.3 kWH per day (100 kWH per month) or less... That is a pretty reasonable amount of solar power for an off-grid home/cabin.

But that is not a cheap system... You are looking at ~1,600 watts of solar panels, an ~800-1,650 AH battery bank (at 12 volts), solar charge controller, inverter, mounts, wiring, fuses, etc... Plus a backup genset and AC battery charger if you need power during poor weather conditions/backup power.

It would not be out of the realm of possibilities to say that this would be a $10,000-$20,000 or more off-grid solar system to install... Plus you would need to replace the batteries every ~4-15 years, and replace electronic hardware every 10-15 years or so...

We can go into the details--but I wanted to understand your power requirements and what you expected from the system (I am not in solar equipment sales, I do not do this for a living--Just trying to help).

-Bill

mike95490

Re: Need Info On A Small Solar System

MIDGAPATRIOT wrote: »

I'm wanting to put together a small solar system. I need to power a well pump, the well is 110' deep. The water would go into a storage tank. I also want to power a refrigerator/freezer, just a normal one like you have in your kitchen. What do I need? How many panels, inverter, batteries, and so forth. I know NOTHING about any of this so any info is GREATLY appreciated. Thanks in advance!!!!

That's just about what i'm doing right now, using a standard well pump, in a pond, to pump water 160' high on a hill to a tank for gravity pressure.

As Bill says, it's expensive. PV. inverter that can start a pump, batteries, backup genset,

Poke around in my .Sig, lots of stuff there.

Mike

MIDGAPATRIOT

Re: Need Info On A Small Solar System

Thanks for that info. This is gonna be a SHTF system. Just wanting to keep a good size tank full of water and run a refrigerator/freezer to keep meat from hunting from going bad. This would not be used to provide the house with it's normal water usage, I know that would be really expensive. Just to fill up the tank, maybe 300 to 500 gallons. And have a float valve/switch to shut off the pump when the tank is full.

mike95490

Re: Need Info On A Small Solar System

MIDGAPATRIOT wrote: »

Thanks for that info. This is gonna be a SHTF system. ....

If you are real good the batteries will last 5-9 years. Then, it's only power when the sun shines. So depending on the size/wattage of your pump, you should have twice that in solar PV to make sure the pump will run.

MIDGAPATRIOT

Re: Need Info On A Small Solar System

mike90045 wrote: »

If you are real good the batteries will last 5-9 years. Then, it's only power when the sun shines. So depending on the size/wattage of your pump, you should have twice that in solar PV to make sure the pump will run.

Like I said I know nothing about this stuff, what is PV?

Kamala

Re: Need Info On A Small Solar System

PV = PhotoVoltaic

That is, solar cells/panels. They convert the energy of massless photons (the "conveyors" of light, or better said, electromagnetic radiation) into electromotive force, more commonly called voltage.

BB.

Re: Need Info On A Small Solar System

PV = Photo Voltaic = Solar Electric Panels/Solar cells

Roughly:

• Solar panels generate voltage and current (typically >17.5 volts and 5-15 amps) of unregulated electricity.
• A solar charge controller takes the power/current from the solar panel and dolls it out to the battery... Adjusting the amount of current required to get the battery fully charged (~14.5 volts full charge, drop back to ~13.7 volts for float/storage charge on a 12 volt battery). Two types of charge controllers PWM (pulse width modulation--less expensive) and MPPT (maximum power point tracking--more expensive).
• Battery--Stores energy and regulates the system DC voltage. Typically from ~11.5 volts to ~15 volts (depending on charging/discharging/state of charge). Rated in Volts and Amp*Hour (or Watts*Hours--how much useful energy is stored in a battery bank).
• Inverter--Takes the DC voltage (from 10.5-15.5 volts) and turns it into 120 VAC. Two types of inverters MSW (modified square wave--less expensive and not "clean sine wave power") and TSW (true or pure sine wave power--same as utility power--more expensive).

Each of these, ideally, should be sized to support the daily loads you wish to operate...

To design a system without knowing your loads is pretty difficult... We could guess that your minimum load is 1.5 kWH per day (Energy Star Refrigerator) plus a few small lights.

Or we could guess 2x that at 3.3 kWH would give you enough power to live a pretty reasonable life style (washer, water pump, radio, some lights, etc.).

Assuming you will install the system somewhere around Macon Georgia--Using PV Watts website, 1,600 watts of solar panels, 0.52 over all system derating, fixed solar array tilted at latitude (note--1,600 watts or 1.6kW of solar panels is just a starting guess--nothing magic about that number):

"Station Identification"
"City:","Macon"
"State:","Georgia"
"Lat (deg N):", 32.70
"Long (deg W):", 83.65
"Elev (m): ", 110
"PV System Specifications"
"DC Rating:"," 1.6 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 0.8 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 32.7"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 7.9 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.59, 86, 6.79
2, 4.66, 103, 8.14
3, 5.46, 129, 10.19
4, 5.88, 132, 10.43
5, 5.82, 130, 10.27
6, 5.47, 116, 9.16
7, 5.60, 122, 9.64
8, 5.52, 121, 9.56
9, 5.01, 108, 8.53
10, 5.38, 123, 9.72
11, 4.58, 105, 8.29
12, 3.73, 90, 7.11
"Year", 5.06, 1365, 107.84

So, if you "want 100 kWH per month" from solar--1.6 kW of solar panels will supply you that amount of energy (or more) for ~10 months of the year.

Battery Bank size should be around 1-3 days of energy storage and a maximum of 50% discharge. For 3.3 kWH of power use per day... Assuming 12 volt battery bank (24 or 48 volt may be better for your needs--but use 12 volts as a start):

• 3,300 WH per day * 1/12 volts * 1/0.85 inverter efficiency * 1 day of no sun * 1/0.50 max discharge = 747 AH @ 12 volts minimum
• 3,300 WH per day * 1/12 volts * 1/0.85 inverter efficiency * 3 day of no sun * 1/0.50 max discharge = 1,941 AH @ 12 volts maximum

The above are just rules of thumb--you may choose somewhere in between or more or less... But this gives a roughly balanced system between solar panels, battery bank, and energy use.

-Bill

MIDGAPATRIOT

Re: Need Info On A Small Solar System

BB. wrote: »

PV = Photo Voltaic = Solar Electric Panels/Solar cells

Roughly:

• Solar panels generate voltage and current (typically >17.5 volts and 5-15 amps) of unregulated electricity.
• A solar charge controller takes the power/current from the solar panel and dolls it out to the battery... Adjusting the amount of current required to get the battery fully charged (~14.5 volts full charge, drop back to ~13.7 volts for float/storage charge on a 12 volt battery). Two types of charge controllers PWM (pulse width modulation--less expensive) and MPPT (maximum power point tracking--more expensive).
• Battery--Stores energy and regulates the system DC voltage. Typically from ~11.5 volts to ~15 volts (depending on charging/discharging/state of charge). Rated in Volts and Amp*Hour (or Watts*Hours--how much useful energy is stored in a battery bank).
• Inverter--Takes the DC voltage (from 10.5-15.5 volts) and turns it into 120 VAC. Two types of inverters MSW (modified square wave--less expensive and not "clean sine wave power") and TSW (true or pure sine wave power--same as utility power--more expensive).

Each of these, ideally, should be sized to support the daily loads you wish to operate...

To design a system without know your loads is pretty difficult... We could guess that your minimum load is 1.5 kWH per day (Energy Star Refrigerator) plus a few small lights.

Or we could guess 2x that at 3.3 kWH would give you enough power to live a pretty reasonable life style (washer, water pump, radio, some lights, etc.).

Assuming you will install the system somewhere around Macon Georgia--Using PV Watts website, 1,600 watts of solar panels, 0.52 over all system derating, fixed solar array tilted at latitude (note--1,600 watts or 1.6kW of solar panels is just a starting guess--nothing magic about that number):

So, if you "want 100 kWH per month" from solar--1.6 kW of solar panels will supply you that amount of energy (or more) for ~10 months of the year.

Battery Bank size should be around 1-3 days of energy storage and a maximum of 50% discharge. For 3.3 kWH of power use per day... Assuming 12 volt battery bank (24 or 48 volt may be better for your needs--but use 12 volts as a start):

• 3,300 WH per day * 1/12 volts * 1/0.85 inverter efficiency * 1 day of no sun * 1/0.50 max discharge = 747 AH @ 12 volts minimum
• 3,300 WH per day * 1/12 volts * 1/0.85 inverter efficiency * 3 day of no sun * 1/0.50 max discharge = 1,941 AH @ 12 volts maximum

The above are just rules of thumb--you may choose somewhere in between or more or less... But this gives a roughly balanced system between solar panels, battery bank, and energy use.

-Bill

Thanks for the info. I don't understand any of it but I'm gonna look stuff up and try to figure it out.