New solar setup

[BrendaQ]

Hi Everyone! I’m new to solar and I think I have bought all the major components. I want to make sure I have correct fuses and wiring. I have the following items: 12v 2000w pure sine wave inverter (Renogy), 2x 200aH 12v amg batteries, 2x 215W solar panels and 1x 200W solar panel, and 60 amp mmpt Renogy Rover charge controller. I wanted to wire the panels and batteries in parallel, but when I do calculations on wire size between inverter and battery bank it needs a wire greater than 2/0. Am I doing something wrong? Also could someone point me to a sample diagram for all the types of fuses needed? Thanks! Brenda

 

[Bobert]

2/0 sounds about right for the inverter. 2000 watts at 12 volts is a lot of amps.

 

[MisterSandals]

Am I doing something wrong?

Have you done an energy audit to see how much energy you use each day? With this number you can determine how much solar and battery you need to meet your expectations.

Since you've already purchased, the planning can be skipped and your expectations can be calculated:

630W solar x 5h estimated solar = 3150Wh per day at 100% efficiency

2x 200aH 12v amg batteries

200Ah AGM

2x 200Ah x 12.8V nominal = 5120Wh storage. 50% usable makes it 2560Wh

Your system should be able to recharge the battery in summer, possibly in winter too since you are in the south.

Your daily usage will be limited to about 2500Wh per day. Less if the sun isn't behaving.

I wanted to wire the panels and batteries in parallel

If you post your panel Voc numbers and your SCCs max input voltage, we can determine optimal panel configuration.

 

[BrendaQ]

Have you done an energy audit to see how much energy you use each day? With this number you can determine how much solar and battery you need to meet your expectations.

Since you've already purchased, the planning can be skipped and your expectations can be calculated:

630W solar x 5h estimated solar = 3150Wh per day at 100% efficiency


200Ah AGM

2x 200Ah x 12.8V nominal = 5120Wh storage. 50% usable makes it 2560Wh

Your system should be able to recharge the battery in summer, possibly in winter too since you are in the south.

Your daily usage will be limited to about 2500Wh per day. Less if the sun isn't behaving.

If you post your panel Voc numbers and your SCCs max input voltage, we can determine optimal panel configuration.

Hi MissterSandals and Bobert,

Thanks for the input. I did do a usage calculation and I rounded it up to 3000 watts/day usage, because of the largest draws from fridge (280 Wh), heater (768 Wh), microwave (250 Wh) and lastly the water heater (1440 Wh). I would like to boondock in the winter and it gets pretty chilly here so I need the heater certainly. Did I drastically over shoot on the water heater draw?

Also per the manual it recommends for two days so I'm at 6000 W.

I worked through the numbers last night and for that draw I need 3X 200ah batteries and 3X more 200W Renogy panels.

I have attached the info on the SCC and panels and if I need to change from series and ditch the inverter (replace) I can do so.

Thanks for all the help!

Brenda

 

[MisterSandals]

Did I drastically over shoot on the water heater draw?

How would we know what your usage is?

280Wh for a fridge sounds about 1/4 what i would expect from a small refrigerator.
How did you come up with that number?

heater (768 Wh)

This is a 1500W heater running for a half hour. Is that what you figured?

microwave (250 Wh)

This is a 1500W microwave running for (250Wh / 1500W =) 1/6 of an hour, 10 minutes a day.

3000 watts/day usage,

3000Wh per day

it recommends for two days so I'm at 6000 W.

What is this all about? With you mixing watts and watt hours interchangeably, i cannot eve guess.

 

[BrendaQ]

How would we know what your usage is?

Point taken.

280Wh for a fridge sounds about 1/4 what i would expect from a small refrigerator.
How did you come up with that number?

The value I determined for the refrigerator was from reviewing some threads on other sites. This frige runs on propane and electric so I would be using it on propane when I don't have access to hookups, therefore, the only draw is for the control board and valve.

This is a 1500W heater running for a half hour. Is that what you figured?

The heater is also propane and I only estimated the draw from the blower motor which is 9.5 amps and after updating that number I now have 1200Wh.

This is a 1500W microwave running for (250Wh / 1500W =) 1/6 of an hour, 10 minutes a day.

The microwave is only 1000W and I don't even use it at all but just threw it in the mix. I do have a generator, so if I got in a pinch and needed the microwave for an extended time I would turn on my gen.

I apologize for the units issues. I'm using 3500Wh per day.

Thanks!

Brenda

 

[Solarcabin Channel]

Hi Everyone! I’m new to solar and I think I have bought all the major components. I want to make sure I have correct fuses and wiring. I have the following items: 12v 2000w pure sine wave inverter (Renogy), 2x 200aH 12v amg batteries, 2x 215W solar panels and 1x 200W solar panel, and 60 amp mmpt Renogy Rover charge controller. I wanted to wire the panels and batteries in parallel, but when I do calculations on wire size between inverter and battery bank it needs a wire greater than 2/0. Am I doing something wrong? Also could someone point me to a sample diagram for all the types of fuses needed? Thanks! Brenda

Need some more info Brenda.

What is the voltage on those panels and do you plan using the 215 and 200 watt together in same system?

 

[MisterSandals]

2x 215W solar panels and 1x 200W solar panel, and 60 amp mmpt Renogy Rover charge controller.

I see the panel specs in post #4, thanks.
Your MPPT can take up to 150Voc (temp adjusted).

You should run all 3 panels in series to take advantage of charging in low light conditions (unless you have shading issues where any of the panels regularly become shaded).

This should produce:
(19.2V + 21.8V + 21.8V) x 9.85A = 618W

Your panels are pretty closely matched so connecting them any way will be good. But having a higher voltage takes advantage of charging in low lighting conditions (early morning, late afternoon, cloudy days).

And all in series, you don't need any Y connectors or fuses on each of the 3 panels (necessary when 3 or more panels/strings in parallel).

 

[MisterSandals]

The microwave is only 1000W

If its a 1000W microwave (cooking power), it probably uses 1200W+ to run. Not a big difference but its nice to get 20% better numbers.

I'm using 3500Wh per day.

I'll use your number:
3500Wh / 618W solar = 5.66h of solar, operating at 100% efficiency to produce this.

My gut feel is you'd need 1000W of solar most times of the year. Far more if you get a few overcast days.

 

[OffGridForGood]

To get an idea of the potential from PV set up - I plugged in 0.618kW into PV Watts Calculator using Albuquerque NM (for example) 35 degree tilt, pointing due south.
The monthly range is 81kWh Dec to 103kWh April per month (Daily average: 2.64kW/day to 3.38kW/day)
PV watts is just an estimate, and some report that PV watts overestimates actual conditions, so I suspect you will fall short of the target 3.6kWh per day using the panels you noted.
If you can fit in one or two more may be more realistic.
For storage, since you don't likely have a lot of cloudy or rainny weather in NM, two days ESS (7.2 kWh) may be enough. ie about three times what you currently have in AGM batteries. Maybe you don't need two full days of ESS, though.

 

[wheelman55]

Brenda. Is this a vehicle or trailer install, or is it a cabin?

 

[wopachop]

the water heater (1440 Wh). I would like to boondock in the winter and it gets pretty chilly here so I need the heater certainly. Did I drastically over shoot on the water heater draw?

Its not on propane? I just ran my 10g water heater off electric and it took 1650watts and its around 50F outside.

 

[MisterSandals]

I just ran my 10g water heater off electric and it took 1650watts and its around 50F outside.

1650W while running? How long did it run? (needed to understand how much power it used)

1650W x 10 min (1/6h) = 275Wh

vs

1650W x 1h = 1650Wh

 

[BrendaQ]

Brenda. Is this a vehicle or trailer install, or is it a cabin?

Hi Wheelman55,

This is for a fifth wheel.

Thanks!

Brenda

 

[BrendaQ]

Its not on propane? I just ran my 10g water heater off electric and it took 1650watts and its around 50F outside.

Hi Wopachop,
It is on propane.

 

[MisterSandals]

This is for a fifth wheel.

Search results for query: 5th

diysolarforum.com

This will show what others have done and are willing to share in "Show and Tell" forum.

 

[BrendaQ]

My gut feel is you'd need 1000W of solar most times of the year. Far more if you get a few overcast days.

To get an idea of the potential from PV set up - I plugged in 0.618kW into PV Watts Calculator using Albuquerque NM (for example) 35 degree tilt, pointing due south.
The monthly range is 81kWh Dec to 103kWh April per month (Daily average: 2.64kW/day to 3.38kW/day)
PV watts is just an estimate, and some report that PV watts overestimates actual conditions, so I suspect you will fall short of the target 3.6kWh per day using the panels you noted.
If you can fit in one or two more may be more realistic.
For storage, since you don't likely have a lot of cloudy or rainny weather in NM, two days ESS (7.2 kWh) may be enough. ie about three times what you currently have in AGM batteries. Maybe you don't need two full days of ESS, though.

I went ahead and purchased three more 200W Renogy solar panels (are super cheap on Amazon now), so that brings the total to 2X at 215W and 4 at 200W. It's a 36' trailer so I'll have plenty of room for all of them.

My new question now becomes what would be the preferred layout. I ran the numbers for the following layouts (series/parallel):

I'm using the / to separate the voltage and amps of each panel, not dividing.

Layout 1 - 2 panels (series) with 3 groups (parallel)
Group1 - P1 - 12V/9.85 amp and P2- 12V/9.85 amp = 24V/9.85 amp and produce (21.8V+21.8V)*9.85amp = 429W
Group 2 - P3 - 12V/10.42 amp and P4 -12V/10.42 amp = 24V/10.42 amp and produce (19.2V+19.2V)*10.42amp = 400W
Group 3 - P5 - 12V/10.42 amp and P6 -12V/10.42 amp = 24V/10.42 amp and produce (19.2V+19.2V)*10.42amp = 400W
Total layout 1- 24V/30.46 amp - Need 8 gauge wire

Layout 2- 3 panels (series) with 2 groups (parallel)
Group1 - P1 - 12V/9.85 amp, P2- 12V/9.85 amp, and P3 - 12V/10.42 amp = 36V/9.85 amp and produce (21.8V+21.8V+19.2V)*9.85amp = 618W
Group2 - P4 -12V/10.42 amp, P5 - 12V/10.42 amp, and P6 -12V/10.42 amp = 36V/10.42 amp and produce (19.2V+19.2V+19.2V)*10.42amp = 600W
Total layout 2 - 36V/20.04 amp - Need 10 gauge wire

Layout 3- 4 panels (series) and 2 panels (series) with 2 groups (parallel)
Group1 - P1 - 12V/9.85 amp, P2- 12V/9.85 amp = 24V/9.85 amp and produce (21.8V+21.8V)*9.85amp = 429W
Group2 - P3 - 12V/10.42 amp =P4 -12V/10.42 amp, P5 - 12V/10.42 amp, and P6 -12V/10.42 amp = 48V/10.42 amp and produce (21.8V+21.8V+21.8V+21.8V)*10.42amp = 908W
Total layout 3 - 24V/20.04 amp - Need 10 gauge wire

Which layout would work best? Also, if you have another layout option please let me know.

Brenda

 

[MisterSandals]

Layout 1 - 2 panels (series) with 3 groups (parallel)

also known as 2S3P

Group1 - P1 - 12V/9.62 amp and P2- 12V/9.62 amp = 24V/9.62 amp

No!
You need to use Vmp and Imp for production calculations.

Which layout would work best?

Let me mess with this to see how to get highest voltage and stay below your SCC's max input voltage (150Voc)

 

[MisterSandals]

For quick and easy work, will assume 20Vmp and 10A for all 9 panels

3S3P = 60V x 30A
Not good because the MC4 connectors are 30A max.

10 panels 5S2P = 100V x 20A (very good)

12 panels 6S2P = 120V x 20A (very good)

But with a 60A SCC
200W x 9 panels / 14V charging = 128A available from array to 12V battery (only harvesting 50%)

200W x 10 panels / 14V charging = 143A (very wasteful with 60A SCC)

 

[wopachop]

It is on propane.

Then you can swap the water heater 1440Wh for around 10Wh.
On propane mine pulls 0.8a but only while the propane is heating. Takes about an hour if the water is room temp.

Fridge around 1a so your 250Wh is pretty close.

I use a little 500w electric heater at night in my small front bedroom. Instead of letting the propane roar and heat the whole trailer.