DIY solar configuration for cabin

[izzygnc]

Hi! Did some research in the threads before i decided to plan my solar install. First off i am building a small cabin about 400sqft. Most appliances will be propane to include stove fridge heater and water heater so no need for huge electricity demand.

This is what i have for my plans (6) 300watt 12v panels for 1800w total. (2) 1000 w 12v inverters tied to (2) 200ah deep cycle batts a piece for total of (4) 200ah batts with (2) 80amp 12v charge controllers tied to each of the battery banks.

My real question is do you think this is sufficient setup. Any suggestions recommendations would be helpful.

Thanks!

[Mike90250]

Stop.
There are 24V inverters and charge controllers out there, That would be a better size for your system.

Until you define your LOADS, we have no idea if your choices are sufficient. If you are running just 3 LED lights for 4 hours, it's way overkill. If you need to power a Sat Dish, router, modem, TV, 3 computers and a bread maker, you are underpowered.

if you are going with 2 inverters, have one be a small one and the other for large loads, and it's mostly left OFF.. The idle/standby draw of large inverters is really bad. or locate a very large inverter 4Kw with good electronics (low idle loss) and use that.

[izzygnc]

Thanks for the input. I adjusted the plan to be 24v panels inverters and charge controllers all adjusted to 24v.

The load will be for 1 tv 3 hrs a day @ about 79 watts. 2 cell phone chargers 3 hours a day a piece @ about 4 watts a piece. 2 laptops @ 75 watts a piece for 3 hours a day a piece. Led lights 5 max 2 on at a time at about 9watts a piece. Well pump less than 1 hour a day on off @ 2100 watts peak.

I roughly estimate 900 watt hrs day and 1000 watt hrs night for load.

Thats the load that will be drawn daily.

Thanks. Input is always appreciated. A quick question also can i leave the batteries at 12v in series each bank?

[Sunking]

Hi! Did some research in the threads before i decided to plan my solar install. First off i am building a small cabin about 400sqft. Most appliances will be propane to include stove fridge heater and water heater so no need for huge electricity demand.

This is what i have for my plans (6) 300watt 12v panels for 1800w total. (2) 1000 w 12v inverters tied to (2) 200ah deep cycle batts a piece for total of (4) 200ah batts with (2) 80amp 12v charge controllers tied to each of the battery banks.

1800 watts is a MONSTER of a Off-Grid System and is not a 12 volt application. Get out of that 12 volt box you are trapped in. You would have to buy two very expensive 80 Amp Charge Controllers to operate at 12 volts.That is just plain crazy talk.

At a minimum requires 24 volts and that is not smart money either because it requires an expensive 80 Amp Charge Controller. So toss your plans in the garbage .

Use Grid Tied panels, they cost 1/2 to 1/4 of 12 volt battery panels. 300 watt panels are not 12 volt battery panels. They are grid tied panels. With 6 of them you wire them 3S2P. Done that way, you will not need any expensive combiners or fuses. Just saved you a ton of money.

You will need a 40 Amp MPPT charger for a 48 volt Battery. A Morningstar MS-MPPT-45 is a perfect fit for you. At 48 volts will allow you to grow to 2400 watts. Just saved you another $900.

With 1800 watts of panels on a 48 volt battery requires a minimum of 300 AH up to 450 AH battery DO NOT USE 12 volt batteries. You will use 6-Volt batteries of the right capacity. Something like USB US L16 XC a 6 volt 385 AH battery. You would need 8 of them to make 48 volts @ 385 AH.

With those batteries you can use up to a 3000 watt Inverter, but I recommend an Inverter no larger than panel wattage. A single 1500 would be a perfect fit.

Partner you plan just plain suks and extremely dangerous because you are stuck inside a 12 volt box. Your way will attack your wallet and possible kill you.

[Sunking]

I roughly estimate 900 watt hrs day and 1000 watt hrs night for load.

Thats the load that will be drawn daily.

Thanks. Input is always appreciated. A quick question also can i leave the batteries at 12v in series each bank?

Cripes sake just caught this. Let me save you another $2000. Hell No you cannot use 12 volt batteries.

Real simple:

24 Volt Battery System:

• Panel Wattage = 1000 Watts. Use 4 x 250 watt GT panel wired 2S2P. DO NOT USE A PRIME Number of panels like 3, 5, or 7.
• Charge Controller = Same Morningstar MS-MPPT-45. Will allow you to grow to 1200 watts. Still a Monster of a system.
• Battery = 24 volt 420 AH. 4 x US Battery US-L16HC XC2 or Trojan L16P wired in series.
• Inverter = 1000 Watt Pro Sine Wave like a Samlex PST-1000-24.

[choob]

Cripes sake just caught this. Let me save you another $2000. Hell No you cannot use 12 volt batteries.

Real simple:

24 Volt Battery System:

• Panel Wattage = 1000 Watts. Use 4 x 250 watt GT panel wired 2S2P. DO NOT USE A PRIME Number of panels like 3, 5, or 7.
• Charge Controller = Same Morningstar MS-MPPT-45. Will allow you to grow to 1200 watts. Still a Monster of a system.
• Battery = 24 volt 420 AH. 4 x US Battery US-L16HC XC2 or Trojan L16P wired in series.
• Inverter = 1000 Watt Pro Sine Wave like a Samlex PST-1000-24.

Hi Sunking

Any reason you recommend the L16P over other trojan batteries?

This is what I have available locally, would you recommend any of these?

http://batteryworld.co.ke/trojan-6-volts-series/

[organic farmer]

I learned a lot by talking [to my neighbors who are already off-grid']. Some of the lessons brought out by locals will repeat those of online forum experts.

[izzygnc]

Hey guys! Well ive tried to take everyones suggestions and other discussions into consideration and changed my solar plan to:

4 24v 320w solar panels
4 6v 230ah duracel silgc batts wired in series
1 24v 600w wind turbine for backup since we have a lot of wind here
1 80a charge controller
1 1000w pure sine wave inverter
1 300w pure sine wave inverter

General load calculations is load watt hrs per day 900 watt hrs per night 1200

Thinking of adding additional 4 batts

Your thoughts on these mods to the plan.

[SunEagle]

Hey guys! Well ive tried to take everyones suggestions and other discussions into consideration and changed my solar plan to:

4 24v 320w solar panels
4 6v 230ah duracel silgc batts wired in series
1 24v 600w wind turbine for backup since we have a lot of wind here
1 80a charge controller
1 1000w pure sine wave inverter
1 300w pure sine wave inverter

General load calculations is load watt hrs per day 900 watt hrs per night 1200

Thinking of adding additional 4 batts

Your thoughts on these mods to the plan.

In case you get no wind or sun (which can happen) I would make sure your battery system can safely provide 2100 watt hours for the day (which that 24v 230Ah will not) or at least have another power source (generator) to overcome the loss of RE not charging that system.

[izzygnc]

Thanks for the suggestion! I plan on having a 4000w propane generator as well for backup emergencies.

[SunEagle]

Thanks for the suggestion! I plan on having a 4000w propane generator as well for backup emergencies.

A generator is also a required tool to get your batteries back up to 100% SOC in case either solar or wind can't do it. Having that backup will save your batteries.

[Shane.R13]

How can i tell what amp charge controller i need if 300 watt panels at 36 volts 8.30 amps wired in 2S2P?

[SunEagle]

How can i tell what amp charge controller i need if 300 watt panels at 36 volts 8.30 amps wired in 2S2P?

With 4 x 300 watt panels you have a total of 1200 watts. Using an MPPT type charge controller you would divide the total wattage by the battery system voltage to determine the amount of amps your panels can generate.

1200 watts / 24 volt battery = 50 amps so you would probably need a 60 amp charge controller
1200 watts/ 48 volt battery = 25 amps so you would probably need a 30 amp charge controller but going up to at least a 45 amp CC would be better.

[Shane.R13]

With 4 x 300 watt panels you have a total of 1200 watts. Using an MPPT type charge controller you would divide the total wattage by the battery system voltage to determine the amount of amps your panels can generate.

1200 watts / 24 volt battery = 50 amps so you would probably need a 60 amp charge controller
1200 watts/ 48 volt battery = 25 amps so you would probably need a 30 amp charge controller but going up to at least a 45 amp CC would be better.

That you for your reply. I'll be running a 24volt system. I have many more quesions but will start a new thread if i can figure out how instead of hijacking someone else's.

[moorerichard2]

Stuck in a 12v box?
Explain why a pair of 6v batteries is better than one 12v.Reggardless of 24v or 48v system.Explain why a 200Ah 12v battery is any different from a pair of 6v 200Ah batteries.