230 watt solar panels question

[ttallos]

I am building a small system for an offgrid outbuilding in Asheville NC. I have 4-230watt 24v sharp solar panels. I am wanting to upgrade the system to 4 more panels (230w) later (for a total of 8 panels) and I have a wind turbine that will provide 1kw. What is the best quality charge controller and inverter size? and how many 6v golf cart batteries would I need.

Here are the specs for the panels and wind turbine:

230 WATTS X 8 Solar Panels = 1840 WATTS
Open Circuit Voltage (V) 37.1
Short Circuit Current (A) 8.48


1000 WATT 24v WIND TURBINE (Max Amps 34, Max Voltage 33.6) Max power 1142 Watts per hr

2840 WATTS


I have heard that it is better to hook the wind turbine to its own charge controller with dump load.
I am going to run various items with this power mainly a small 120v radio, a 12v water pump and some lights.
Any advice would be appriecated.

[Naptown]

That amount of wattage really should be at 48V unless you plan to separate into several smaller systems.

[ttallos]

48 volts is fine

Since I only have the panels I could do anything I want 48 volts sounds good. I could hook up half the panels in parallel 2 times and then wire both halves in series. What do you think?

[Naptown]

How you connect the panels depends on the Vmp on the panels. What is it. You may be better off with either 6 or 9 panels. You need to keep the voltage high enough to charge the batteries but below the rated voltage of the charge controller at Voc on the coldest recorded temperature for your area.
You will need at least a 45A MPPT charge controller for the Solar (based on a 48V system).

[Mike90250]

Untill you know what your loads are, you should not be talking panels and batteries.

1 define the loads
2 loads define the batteries
3 size of batteries defines the array to recharge them.

But now you have the cart in front of the horse, and we all know how that generally works out.

[Naptown]

Untill you know what your loads are, you should not be talking panels and batteries.

1 define the loads
2 loads define the batteries
3 size of batteries defines the array to recharge them.

But now you have the cart in front of the horse, and we all know how that generally works out.

To add one more thing to the list daily insolation. This will also determine battery bank size as for instance in a place like Seattle where there is very little insolation therefore the wattage on the panels will necessarily need to be high. one must be careful of charge rates on the batteries so as not to destroy them by feeding in too much current.

[ttallos]

I see what you mean

This stuff is a gift the 8 panels so I am just going to hook up a radio some lights and a frige or freezer if this small size will handle it. I realize that it may NOT. I have a friend that has been off the grid for 2 years. He told me that it is best not to spend alot of $$ on batteries the first go around because most novice users just burn them up anyway. I am getting 12v (105Ah) golf cart batteries as a result.


It sounds like I need to figure out what kind of load I would need to run.
Then compute the battery bank size needed.
Then figure the array size based on that.

Still I am going to get these 8 panels I was thinking 8 12v batteries to start

Thanks for the advice on the 45w charge controller. I am going to go with Outback or Xantrex

[Mike90250]

....
Thanks for the advice on the 45w charge controller. I am going to go with Outback or Xantrex

Also consider the Morningstar MPPT 45 & 60, and the Midnight Classic , both of which I feel have a better human/computer interface than Outback or Xantrex.

[Naptown]

This stuff is a gift the 8 panels so I am just going to hook up a radio some lights and a frige or freezer if this small size will handle it. I realize that it may NOT. I have a friend that has been off the grid for 2 years. He told me that it is best not to spend alot of $$ on batteries the first go around because most novice users just burn them up anyway. I am getting 12v (105Ah) golf cart batteries as a result.


It sounds like I need to figure out what kind of load I would need to run.
Then compute the battery bank size needed.
Then figure the array size based on that.

Still I am going to get these 8 panels I was thinking 8 12v batteries to start

Thanks for the advice on the 45w charge controller. I am going to go with Outback or Xantrex

Avoid batteries in parallel instead of 8 12V batteries get 8 6 volt batteries in the end they will work better and may give you a higher AH rating for the same cost. Besides most golf cart batteries are 6V anyway.

[ttallos]

Thanks for the clarification check this picture out

4 group (s) of 2 batteries in series at 12 volts & 200 AH produce a 12 volt battery bank at 800 Amp Hours capacity.

By the way I love the Morningstar MPPT 60, it looks like a good fit for me. They also have a really great String Calculator to help with the design!

I will upload a picture of the array config next. And before I finish this thread I will have a schematic of my whole system. Thanks for all the help!

[Naptown]

4 group (s) of 2 batteries in series at 12 volts & 200 AH produce a 12 volt battery bank at 800 Amp Hours capacity.

By the way I love the Morningstar MPPT 60, it looks like a good fit for me. They also have a really great String Calculator to help with the design!

I will upload a picture of the array config next. And before I finish this thread I will have a schematic of my whole system. Thanks for all the help!

The problem is equal charging and discharging on a parallel battery bank. The batteries in the middle will fail first taking out the entire bank with them. Series stringing on batteries is always better in the long run.
If you have not purchased the batteries yet please seriously reconsider going to 6 volt in series.
And it actually produces an 800AH bank at 24V
Series batteries voltage builds parallel batteries amperage builds.
So the way you have them configured in 4 parallel strings of 2
2 200AH batteries in series is 200 AH @ 24V
4 24V 200AH batteries in parallel is 24V @800 AH =9600 watt hour which is what you calculate in
If you insist on 12V batteries go 48V with 2 strings of 4 batteries in series.
Several things will happen
1- it will be easier to balance the battery charge/discharge to maintain longest life.
2- Wiring from battery to inverter will be smaller.
3- Higher voltage from the array will be better managed.
4- You will be able to put more wattage from the array on the same charge controller
(remember amperage on the CC is output amps.) divide wattage of array by battery voltage.
So 2400W @24V = 100A
2400W @ 28V = 50A

[ttallos]

6 Volt Sounds good

OK I think the 6v was the cheaper battery! I will switch to that

[Naptown]

OK What about this array design check out this picture.

Better for design and charging but bank will be 48V 200AH
Remember series voltage builds
Parallel amperage builds

[ttallos]

Amp Hours

Thanks correction made!