What Do I Have?

[cohunter14]

I am looking at purchasing a remote cabin in Colorado that currently has a solar setup with the cabin. The current setup includes two panels, one that is 80 watts and one that is 100 watts. There are also six GC2 Interstate Batteries. There are two different inverters, one that is 400 watts and one that is 2,000 watts (which I believe the current owner uses to power a toaster or any other item needing more juice). Based on our location, we are somewhere between 5.5 and 6.0 kWh/m2/Day.

I am totally new to all of this and have been doing a bunch of reading, but I just want to make sure I'm understanding everything correct. My questions are:

1) Is this a decent setup?
2) Am I right in thinking the biggest limitation to this current setup is the panels? If I added panels, I should be able to better utilize the batteries, correct?
3) Based on my reading, I am thinking these current solar panels should produce roughly 1,000 watt hours/day. Is that correct?
4) Also based on my reading, I am thinking these batteries should hold roughly 4,200 watt hours, on average. Is that correct?

If my assumptions are correct (I'm not surprised if they aren't!), would it be correct in thinking that although the batteries hold roughly 4,200 watt hours, I wouldn't want to use more than 50% of that in a given day, or roughly 2,000 watt hours? And, again, if my assumptions are correct, would that mean I need to double the solar panel wattage to maximize the system?

I apologize if I am way off with all of this. As I said, I am not only new to this, but I am trying to learn based off of a system I am looking to buy and not one I am building, so just trying to wrap my arms around everything. Thanks, in advance, for any help!

 

[Wellbuilt]

Well 300watts should give you about 1000watt a day .
2 gc battery’s make 12 volt @ 230 amp hours x 3 so 690 ah @ 12 .8 volt = 8832 watts at 50% discharge Is 4415 watts but I would try not to go below 20% very often .
but the system is not balanced , 6 GC battery’s need 1500 watts to stay charged .
I think the battery’s are probably sulfated from lack of charging If the system was being used more the a couple days a month .
It depends how much power was drawn from the battery’s per day .
Depending how you use the cab, you would want to move up to a 24volt inverter / charger 8 6 volt GC battery’s
and 15 to 2000watts of solar and quality charge controller. and genarator for bad weather .

 

[45North]

Baby steps!

• decide if you want to buy the place on its own merit (ask the owner/builder if he has any documentation on the solar system)
• hookup the existing system and use it for something - anything just for practice
• study the subject and familiarize yourself with solar theory and practice
• only After the above steps will you be in a position to decide if there are any components you should add or replace

 

[cohunter14]

I think the battery’s are probably sulfated from lack of charging If the system was being used more the a couple days a month .
It depends how much power was drawn from the battery’s per day .

The system was not used much over the last few years. Probably less than a couple days a month.

Depending how you use the cab, you would want to move up to a 24volt inverter / charger 8 6 volt GC battery’s
and 15 to 2000watts of solar and quality charge controller. and genarator for bad weather .

The cabin is pretty rustic and only used for some lighting and charging a few items in it's current state. We might try to expand on that, so it's good to know this would be an option. We could initially go to 1,500-2,000 watts of solar panels with the current batteries and then expand to 24 volt if we decided to, right?

Baby steps!

• decide if you want to buy the place on its own merit (ask the owner/builder if he has any documentation on the solar system)
• hookup the existing system and use it for something - anything just for practice
• study the subject and familiarize yourself with solar theory and practice
• only After the above steps will you be in a position to decide if there are any components you should add or replace

Thank you for the advice! I have spoken with the owner on a lot of it, but I'm just trying to learn more about the system myself so I know what it's capable of. The last thing I want to do is go to use it the first time and run out of power while I'm there.

 

[cohunter14]

Well 300watts should give you about 1000watt a day .

Sorry, forgot to ask this in the last post, but are you saying 300 watts of panels should give me 1,000 watts a day? So, the 180 watts of panels that are currently in place would get me roughly 600 watts a day?

 

[Wellbuilt]

O sorry I miss read the post 180 watts would get 180x4.5 sun hours ?= 800 watts this time of year.

 

[Wellbuilt]

With only 180 watts of solar on 6 battery’s for years the battery’s are probably dead or dying
My system has 16 GC battery’s and 4500watts of solar soooo 281 watts per battery ?
my system has extra power for this time of year .
6batterys x281 watts each = 1686 watts so you are really only trickel charging the batterys with 180 watts.

The thing is , 6 series / parallel 6 volt battery’s is hard to charge evenly .
Here is the rub ,,,,,@ 12 volt you can get a out back fm80 charge controller and you can have 1000watts of solar on it .
@ 24 volts you can have 2000 watts of solar .
with a 48volt system you can have 4000 watts or a little more I have 4500 watts so a little over paneled.

if you have 6 panels you can run 3 in series with 2 strings my panels are 295 watts so 3 in series would be 885 watts
I can get about 750watts out of that string so if you had 2 strings you can get1500 watts.
if you are there hunting in nov / DEC you won’t get much power and when it snows uggg (no power)
so you will need a genarator and charger to maintain the batterys .
The best way to do this , is to charge with a inverter / charger , sooo that is why I was talking 24 volt inverter.
most Chinese inverters use a lot of power just being turned on .
The larger the inverter the more power it will use.
What you should do is figure out what you want to power and when .
In my mind a 12v system is for a RV wit all 12 volt appliances
a 24volt system is ok for a small cabin up to 2000watts
48v is every thing else .
If you stay 12 volt I would lose 2 battery’s keep the best 4 and add a good quality 80amp charge controler with 2 strings of 2 300 watt panel so 1200 watts .
If you want to have a fridge you should move up to 24 volts and if you move up I would just go 48volts and use 8 sams club GC battery’s .
My place was buried In snow for 10 week this winter. I ran a Honda 2800 watt inverter genarator 12 to 14hours a week .
What ever you do don’t add new battery’s to old batterys ?

 

[Wellbuilt]

This looks very interesting i am rich posted a link to this this morning .
There is a 24volt unit for 500 and change .
It’s new so no track record but mid nite makes good stuff .
the 24 volt unit is a few bucks more then the charge controller
I do think you get what you pay for with solar equipment

 

[cohunter14]

2 gc battery’s make 12 volt @ 230 amp hours x 3 so 690 ah @ 12 .8 volt = 8832 watts at 50% discharge Is 4415 watts but I would try not to go below 20% very often.

Thanks for all of the great information! So, you had mentioned this earlier. As a follow up to that, if I am only using 20% of the 8,832 watts, as you recommend, that's 1,766 watts. If our location provides between 5.5 and 6.0 kWh/m2/Day, wouldn't that mean I'd need roughly 320 watts of solar panels to replace that usage each day? (1,766 / 5.5 = 321).

At this point I am not sure what we will end up powering. It obviously doesn't have a refrigerator now, but maybe at some point? For now, I'd just like to optimize the system that's in place as best I can, while also understanding the power I have available to me. We will primarily use the cabin during the summer and in September for hunting, so the panels should still be receiving good sunlight. With that being said, would you still recommend only using four batteries and just getting two 300 watt panels? And what would the reasoning be to drop two of the batteries? Just to make them charge more evenly? Wouldn't it make more sense to add three 300 watt panels at that point and keep all six batteries?

Sorry for all of the questions. It's all so new to me and I'm just trying to wrap my head around everything.

 

[Wellbuilt]

Well you have to replace the power you used ( over night ) 20% but you still need power to run the cabin when charging
All day . I use 3200 watts over night but make 5000 watts a day for day time loads and power losses .
im in ny so I get 4.5 sun hours you may get more but power drops off in September fast.
Your panels are made in sizes mine are 295 watts each so 2 panels are 590 watts
This is not really enough to power 4 GC battery’s @ 10% rate of charge .
Soooo you could add a second string ? for double the power .
You could use 3 panels with 3 strings but then you need a Combiner box So the 4th panel is a wash .
If you re read the post above I was talking 2 panels in series and 2 strings soooo (4 panels total ) 1200 watts.

As far as battery’s go your best bet is to have i string of battery’s so 2 6v battery’s in series for 12 volt ,
this has a very even charge and discharge ( this keeps battery’s healthy and last the longest but is not enough power .
So you could add a second string ? you get double the power , but it a little harder to balance 2 strings .
3 strings ? Is generally not good practice and you end up with battery’s out of balance So the battery with higher voltage get charged to full , the battery’s with lower voltage lag behind and start to sulfate , then the lower battery’s drag down the good ones .
I’m sure you will find 2 battery’s in the bunch that are much weaker then the others , plus if you don’t have a frig 4 batterys would be enough power .
You could get away with 2 battery I would think , I started with 2 battery in my trailer with a 300wat morning star inverter , I could run lites tv radio c-pap unit over night 400 watts of panels worked most of the year but could of use 200watts more .
I have cheep GC battery that are 7 years old and still have 80% power .
dont worry about all the questions We all started out in your shoes ?

 

[cohunter14]

A lot of this makes sense to me and I appreciate you explaining it all. So, two additional questions I guess: first, if this was your system and you wanted to optimize what was there while spending as little as possible, what would you do? Could I add two 295 watt panels, for example, and use them with the current 100 watt and 80 watt panels? And then, I assume you would suggest taking the four best batteries and using those in that setup and disconnecting the other two? What usable wattage could I expect to have each day from that setup?

The other question would be somewhat similar: if this is what I have in place, what would be the best route to really optimize this setup while continuing to use as many components as possible? Probably going to an 8 battery setup and 48 volts? How many panels would you suggest in that setup, and what else would I need? I assume I couldn't continue using the same inverters? And, similar to above, what usable wattage could I expect in a setup like this?

 

[Wellbuilt]

Well it’s not reall as simple as all that.
I have no idea what equipment you have ?
The way it sound , with your description , is you don’t really have much to start with at all .
2 inverters ? I’m betting that they are not worth more then 200/ 300 bucks .
You could just use the 180 watt of solar the way it is , and add 2 300watt panels but I think 600 watts is not really
enough with the old panels and charge controller you would have (all most enough power )
but you would need a new controler for the new panels ,you could spend 200 bucks on a cheep unit , that may not last to long .
I would get a good unit 4/500 bucks ( Midnite outback snider )This could be used later with a new system .
These will all taok to the matching inverter in the future

 

[Wellbuilt]

Whoops my screen froze,
these will all talk to the matching inverter ?
how much wattage will you get ?
In June you will see 75% of the watts of the system 600 watts 75% =450 watts for 5 hours so 2100 watts or so .
Plus the old panels how ever much power they will put out?
You could try and limp along with what you have but I would not bother , you have a learning curve and it would be better to start learning with equipment that you can have for 10 15 years that will meet your needs .

Now the reality of it all is you will need a genarator and battery charger to charge the battery’s on bad days If the battery’s are left uncharged for a few day they start to die .

With 180 watts of solar on 6 GC battery’s they may allready be dead or dyingIt’s not enough power to keep them happy .
The cheep way out mite be to buy this little system you could use 4 of your battery’s with it if they are good .
hook 6 or 700 watts of new panels or more , to it that you need any way .
If you are running out of juice , this system has a built in battery charger ? so you can just run for a hour in the morning before the sun comes up .
Lots of good here in this little box.
I would go 48 volts but i need a system that is easy to use that dose every thing I need .

For a few bucks more you could get the 48volt unit in this post above .
I have the out back system below
so you can see the difference .
I would buy from Arazona Wind And Sun if you need help they are a phone call away .

 

[Wellbuilt]

On other thing , I use 2/300watts of power .
And 100watts over night .
It’s not like you are burning power like crazy .
My cabin is 2800sf and I have 68 led hi hats and 25 out side lights .
And every thing a regular house has frig frezzer TVs radios and 8/9 months out of the year I don’t even check the power room
The system is automatic and takes care of it self .
It’s cool in my area 50s over night so no ac
A larger then needed battery bank useing 10 20% can last longer , I know a guy that get 10 years out of his battery s

 

[cohunter14]

The cheep way out mite be to buy this little system you could use 4 of your battery’s with it if they are good .
hook 6 or 700 watts of new panels or more , to it that you need any way .
If you are running out of juice , this system has a built in battery charger ? so you can just run for a hour in the morning before the sun comes up .
Lots of good here in this little box.

Sorry, just to clarify: are you referring to the MN3024DIY with this statement? You would recommend getting that along with 600 or 700 watts of new panels if I wanted to go the cheap route? I could then utilize my old panels as well?

I know you asked, and it looks like the current system has a 400 watt Coleman Powermate inverter and a 2000 watt Vector Maxx inverter.

 

[Wellbuilt]

I think that mite be your best option .
For a complete system 500 and change
Seams cheep for a system that can work

for you .
A little story for you , I set up my trailer with solar panels 2 go battery’s from sams club a 300 watt morning star inverter
I bought a 40amp mppt popular charge controller
The charge controler work great for one year and 13 days then died
It ended up taking the battery out with it
The unit was 13 day out of warrantee
Your inverter mite make power but will not last and you really should get a pure sinwave inverter . .
You could mess around with the parts you have for months and in the end it may not work .
I think the 24watt diy system could work for you for thin money but a 48 volt system would be better in the long run .
8 golf cart battery will charge and discharge the best
You could add twice the panels on the same charge controler .
If I was buying a cooler for beer or A Canoe I would look at Colman but electronics not so much
The 6 700 watts of panels would work for most of the year
A 3000watt generator for 300 bucks would keep up charged up on off days