I purchased a 3000/6000w, 24v Inverter with an 80 amp charge controller built in. I have 8 - 6v 225 amh deep cycle batteries, 4 - 275w solar panels and #2/0 cable w/ copper lugs. I also have #10 wire to connect to the controller from the panels. Would anyone consider helping me with proper wiring connections for both my battery bank and my panels? I haven't any experience with 24v and don't want to destroy any equipment or myself. I live close to the northern border in the PNW and I'm trying to see if I can run a small heater for colder days. Any knowledgeable input would really ease my hesitant attempt. Thank you in advance. Bob. 11/4/22
A Little Hesitant
- Thread starter BobbyP
- Start date
MichaelK
Solar Wizard
Well, I can see already that there are problems ahead for you. Having lived before in both Washington and Oregon, I know how cloudy it is for a large fraction of the year. The fact that you want to run a heater on colder days is an indication, that you need solar the most when your solar resource is at a minimum.
The components you've already got will make a good 24V system, but you desired application for winter heating is most likely to be a failure. In Southern California, you'll make lots of power with it, but in the PNW, don't expect to see more then 10% output from your panels. And electric heat is just about the worst application you can use solar for.
First, wire the batteries in two parallel strings of four 6V batteries. You can position them such that they form a U shape to cut down on the wiring distance. Let's call the four batteries in string #1 as 1,2,3, and 4. The four batteries in string #2 would be 5, 6, 7, and 8. To get the most equal charging, wire the positive terminal of battery #1 to your charge controller battery+ terminal, and the battery #8 negative terminal to your charge controller battery- terminal. It will look something like this, though the batteries in the pic are in a straight line, not a U. Use the 2/0 wire here. The over-current protection means either fuse or breaker, rated for 200A.
Once you have the batteries wired together, check the voltage with a voltmeter. It should be at 25-26V just sitting there.
Next, connect the +terminal of battery #1 to the battery + terminal on the charge controller. Connect the - terminal of battey #8 to the - battery terminal on the controller. Once the controller gets power, let it boot up and wait for the expected display to be shown. ALWAYS connect the controller to the battery first.
Now you are ready to connect your solar panels. What brand of controller do you have, and what is its voltage limit? Also, what is the Voc and Vmp of your panels? I'll guess the Vmp is ~30V, and the Voc is 37V? Two panels in series is the most you could wire if your controller has a 100V limit. You would wire the four panels 2S2P. That means two parallel strings of two panels in series. Use 4 gauge wire here.
Let's start with just two panels. The + connection of panel #1 goes to the + solar terminal of the charge controller. The - connection of panel #1 goes to the + connection of panel #2. Finally, the -connection of panel #2 goes to the -terminal of the charge controller. Again, just like the batteries, they can be fused or breakered, though for each string you need a 15A fuse/breaker.
You might want to cover the panels with a blanket when you first make your final connections, so a lot of current doesn't immediately start flowing. Once the connection is made, pull off the blanket and see how much power is coming in.
Finally, connect the inverter terminals to the battery strings. Use the same 2/0 cable to connect the inverter +/- to the same battery +/- that everything else is connected to. Once the inverter is connected, turn it on, and plug in a small load, such as a single light bulb lamp. Once you see that working, start plugging in larger and larger loads to see how the new system performs.
Once you know that the minimal system is up and running, you can connect the second solar string to the same terminals to bring it up to full power.
Good luck
The components you've already got will make a good 24V system, but you desired application for winter heating is most likely to be a failure. In Southern California, you'll make lots of power with it, but in the PNW, don't expect to see more then 10% output from your panels. And electric heat is just about the worst application you can use solar for.
First, wire the batteries in two parallel strings of four 6V batteries. You can position them such that they form a U shape to cut down on the wiring distance. Let's call the four batteries in string #1 as 1,2,3, and 4. The four batteries in string #2 would be 5, 6, 7, and 8. To get the most equal charging, wire the positive terminal of battery #1 to your charge controller battery+ terminal, and the battery #8 negative terminal to your charge controller battery- terminal. It will look something like this, though the batteries in the pic are in a straight line, not a U. Use the 2/0 wire here. The over-current protection means either fuse or breaker, rated for 200A.
Once you have the batteries wired together, check the voltage with a voltmeter. It should be at 25-26V just sitting there.
Next, connect the +terminal of battery #1 to the battery + terminal on the charge controller. Connect the - terminal of battey #8 to the - battery terminal on the controller. Once the controller gets power, let it boot up and wait for the expected display to be shown. ALWAYS connect the controller to the battery first.
Now you are ready to connect your solar panels. What brand of controller do you have, and what is its voltage limit? Also, what is the Voc and Vmp of your panels? I'll guess the Vmp is ~30V, and the Voc is 37V? Two panels in series is the most you could wire if your controller has a 100V limit. You would wire the four panels 2S2P. That means two parallel strings of two panels in series. Use 4 gauge wire here.
Let's start with just two panels. The + connection of panel #1 goes to the + solar terminal of the charge controller. The - connection of panel #1 goes to the + connection of panel #2. Finally, the -connection of panel #2 goes to the -terminal of the charge controller. Again, just like the batteries, they can be fused or breakered, though for each string you need a 15A fuse/breaker.
You might want to cover the panels with a blanket when you first make your final connections, so a lot of current doesn't immediately start flowing. Once the connection is made, pull off the blanket and see how much power is coming in.
Finally, connect the inverter terminals to the battery strings. Use the same 2/0 cable to connect the inverter +/- to the same battery +/- that everything else is connected to. Once the inverter is connected, turn it on, and plug in a small load, such as a single light bulb lamp. Once you see that working, start plugging in larger and larger loads to see how the new system performs.
Once you know that the minimal system is up and running, you can connect the second solar string to the same terminals to bring it up to full power.
Good luck
Thanks MichaelK, The battery bank diagram was perfect.
The inverter has an 80 amp charge controller built in the unit and the panels VMP 32.1v & VOC 39v. 4 panels @ 275w =1100w combined total.
Being a 24v inverter I believe the controller should handle the 4 panels?
Is there a diagram available showing the panel wiring for all 4 panels?
I will have to acquire some fuses/breakers as I was not aware of their importance, thanks.
Your right about the sun, up here, as I've got a tiny 200w heater which, hopefully will help conserve a little of my firewood.
BobbyP
The inverter has an 80 amp charge controller built in the unit and the panels VMP 32.1v & VOC 39v. 4 panels @ 275w =1100w combined total.
Being a 24v inverter I believe the controller should handle the 4 panels?
Is there a diagram available showing the panel wiring for all 4 panels?
I will have to acquire some fuses/breakers as I was not aware of their importance, thanks.
Your right about the sun, up here, as I've got a tiny 200w heater which, hopefully will help conserve a little of my firewood.
BobbyP
Rednecktek
Solar Wizard
So a few things to rain (pun intended) on your plans:
The batteries: 6v @ 225Ah * 8batt = 10.8KWh of battery. AGM is only usable to about 50% DoD so in reality you're looking at 5400Wh. That 200w heater will run for about 27 hours before the batteries are completely dead.
That's not a lot of runtime for you and here's why: When it's raining and/or overcast like we get between October and March, you'll be lucky to get 10% out of your panels. That's 110w per hour for (if you're lucky) 4 hours which is only 440Wh, or 2 hours of heater time recharged per day.
Is this going in a shed or barn or cabin or something? Have you heard about Diesel Parking Heaters? Yes, it requires another fuel but it also runs on DC power and not much of it at all. My cabin out in Ione has 2 and I burn about 10gal per week combined to keep the inside at 68F when it's 10F outside.
Attached is a basic 2s2p wiring diagram in krappy MSPaint.
As a reference, out in Monroe I have a 300w panel setup that can't generate 120Wh in a day for 4 months a year.
The batteries: 6v @ 225Ah * 8batt = 10.8KWh of battery. AGM is only usable to about 50% DoD so in reality you're looking at 5400Wh. That 200w heater will run for about 27 hours before the batteries are completely dead.
That's not a lot of runtime for you and here's why: When it's raining and/or overcast like we get between October and March, you'll be lucky to get 10% out of your panels. That's 110w per hour for (if you're lucky) 4 hours which is only 440Wh, or 2 hours of heater time recharged per day.
Is this going in a shed or barn or cabin or something? Have you heard about Diesel Parking Heaters? Yes, it requires another fuel but it also runs on DC power and not much of it at all. My cabin out in Ione has 2 and I burn about 10gal per week combined to keep the inside at 68F when it's 10F outside.
Attached is a basic 2s2p wiring diagram in krappy MSPaint.
As a reference, out in Monroe I have a 300w panel setup that can't generate 120Wh in a day for 4 months a year.
Attachments
DerpsyDoodler
Solar Addict
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What inverter did you purchase? Brand and model? Can you provide a link? Hold off on spending anymore money until you can get some advice from the folks here.
Your inverter should have specs designating max input PV voltage.
12VoltInstalls
life passes by too quickly to not live in freedom
Pretty sure those are flooded not AGMs?
And not dissing you, but with the expected load, a lead acid battery bank will not likely deliver that full 27hours that math would indicate because lead acid has an attitude about discharge rate.
Info on charge controller needed. Brand and model. Some of those lower-shelf inverters with charge controller are PWM which likely will effect your panel arrangement. At 24V at expect an mppt though.
Wildhat guessing you’ll want another four panels, minimum, to use the heater while still recharging batteries adequately- if you can get enough sun
Need to know max volts for the unit
Without knowing SCC specs I don’t know what to suggest
Panel voltage has no relevance to battery voltage. The charge controller handles that.
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From Amazon, as Eco-Worthy... 3000/6000w 24v Pure Sine. I feel confident that all my components will jive
but correct wiring is paramount. A couple of friendly and knowledgeable folks have helped w/ diagrams and my construction will move forward. Thanks...Derpsy
Hey Rednecktek... Thanks for responding. Solar energy, in our area takes a back seat to our water on demand environment! I wouldn't live anywhere else.So a few things to rain (pun intended) on your plans:
The batteries: 6v @ 225Ah * 8batt = 10.8KWh of battery. AGM is only usable to about 50% DoD so in reality you're looking at 5400Wh. That 200w heater will run for about 27 hours before the batteries are completely dead.
That's not a lot of runtime for you and here's why: When it's raining and/or overcast like we get between October and March, you'll be lucky to get 10% out of your panels. That's 110w per hour for (if you're lucky) 4 hours which is only 440Wh, or 2 hours of heater time recharged per day.
Is this going in a shed or barn or cabin or something? Have you heard about Diesel Parking Heaters? Yes, it requires another fuel but it also runs on DC power and not much of it at all. My cabin out in Ione has 2 and I burn about 10gal per week combined to keep the inside at 68F when it's 10F outside.
Attached is a basic 2s2p wiring diagram in krappy MSPaint.
As a reference, out in Monroe I have a 300w panel setup that can't generate 120Wh in a day for 4 months a year.
I'm in a tiny cabin in the forest with a woodstove and propane backup. I hate to fell live trees so I thought my 200w heater would be a great 2nd backup in the milder months, the 45° ones.
If it doesn't get it I'm looking to try using this extra power for my "buzz box" and small summer projects.
I truly appreciate the diagram and input.
Out for now... BobbyP
12VoltInstalls
life passes by too quickly to not live in freedom
I don’t think that unit will run a stick welder.
And the SCC is pwm “ECO-WORTHY 3KW Off-Grid Hybrid Inverter contains a 24V DC to 110V AC Pure Sine Wave Inverter + 80A PWM Solar Charge Controller, suitable for charging your 24v battery bank with solar or mains power.”
I think an mppt with series panels is really what you need to use to get low-light charging you probably won’t get with pwm
Rednecktek
Solar Wizard
True, I was napkin-mathing there.
DerpsyDoodler
Solar Addict
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The solar charge controller in your unit is PWM and cannot handle a VoC of more than 60v.
This means you have to connect all your panels in parallel, and you won't get the full power they can provide. You'd have been better off purchasing 12v or 24v panels.
Just to second MichaelK's comments, here in the Willamette Valley I see about 10 percent production during January and February, meaning one of my 5kw arrays will put out about half a kilowatt hour of energy per day on a lot of days. Sometimes we have a bunch of those in a row, other times the clouds thin out a bit and we get a day of 20-30 percent production. That's why I have 6 days of storage in the battery system.
The other issue is that lead acid batteries are really tough in this environment because they really want to be topped up full very regularly, combined with the fact that the absorption phase, that last 10 percent, is really inefficient and seems to take forever. You will definitely need a generator to top up your batteries in the middle of the winter to keep your batteries from sulfating and being damaged.
The good news is that when it's REALLY cold here, it's almost always sunny, versus the day to day chilly and cloudy, and once you make it to March solar production really starts to increase. I've gone from 1-2 kWh per day of production in January to 20-30 kWh per day production the last couple of weeks and in another month we'll have tons of power.
One other consideration, if you can afford it, is to get a small heat pump. They put out a lot more power per watt than a radiant heater. I have a 12K BTU that does 90 per cent of my heating and it takes less than 1000 watts of power to do it.
The other issue is that lead acid batteries are really tough in this environment because they really want to be topped up full very regularly, combined with the fact that the absorption phase, that last 10 percent, is really inefficient and seems to take forever. You will definitely need a generator to top up your batteries in the middle of the winter to keep your batteries from sulfating and being damaged.
The good news is that when it's REALLY cold here, it's almost always sunny, versus the day to day chilly and cloudy, and once you make it to March solar production really starts to increase. I've gone from 1-2 kWh per day of production in January to 20-30 kWh per day production the last couple of weeks and in another month we'll have tons of power.
One other consideration, if you can afford it, is to get a small heat pump. They put out a lot more power per watt than a radiant heater. I have a 12K BTU that does 90 per cent of my heating and it takes less than 1000 watts of power to do it.
Hey Derpsy... Thanks so much as you saved my bacon. There were a lot of nice features on the Eco-Worthy inverter but I'm needing to max my system in winter and that charge controller, with your heads up, pushed me off the edge. It's scheduled for return and I just ordered a 100 amp controller and a different inverter.
It will still be a 24v set up and your sayin' wired in series will be best or will another configuration will work better?
Thanks in advance for your time and input. BobbyP out.
DerpsyDoodler
Solar Addict
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I'n ha
It's good that you scheduled the return on what you already had, but hold off on making any more orders until the folks here can help get you squared with what you'll actually need and a good plan.
You have a lot of good eyes on this thread. Read their responses and start asking questions.
Happy to help, but strongly suggest you refer to bvillebob, michaelk, and rednektek's posts, here. They are clearly on top of your plight. They have experience with solar in your area, and as they've already pointed out, you're going to need a lot more PV to do what you want and have made suggestions for more efficient ways to do what you want. You have a lot to consider at this point.
It's good that you scheduled the return on what you already had, but hold off on making any more orders until the folks here can help get you squared with what you'll actually need and a good plan.
You have a lot of good eyes on this thread. Read their responses and start asking questions.
Can do, bro
