Charge controller - inverter wiring questions

[rickoxo]

Here's a picture of a basic wiring diagram for my solar setup:

pic of solar basics.JPG

First question, is this wiring diagram correct? If it is, here's what I don't get. The charge controller connects to the battery via the battery terminals. The inverter connects to the battery the same way, via the terminals. So doesn't that mean that the charge controller is directly wired to the inverter? Can you just skip the battery?

So, what happens if it's solar noon, the panel is producing maximum voltage, the battery is full and the inverter has something plugged in but it only needs a little power? I'm sure there's something I'm not understanding, but it seems like because the charge converter and the inverter are both connected at the battery terminals, that they end up being directly connected as well. Maybe if the battery was low on charge, some of the power could get sucked into the battery first before going along to the inverter, but what if the battery is fully charged?

Thanks,

Rick

[Sunking]

First question, is this wiring diagram correct?

Yes minus some protection devices.

If it is, here's what I don't get. The charge controller connects to the battery via the battery terminals. The inverter connects to the battery the same way, via the terminals. So doesn't that mean that the charge controller is directly wired to the inverter? Can you just skip the battery?

No and no. What you do not understand is a solar panel is a variable current source of unknown quantity. , not a constant voltage source like a battery.

[wotechsolar]

dear, Sir

Have a nice day!
Firstly, we added the photo, which can help you understand the linking way better.
the linking way is right.
there are six terminals on the controller.
two for solar panel.
two for battery
two for DC appliances.

secondly, controller---- battery---inverter--- AC Family applinaces.
if you directly link inverter with controller, will cause the current shortage. had better not do that.

[Sunking]

dear, Sir

Have a nice day!
Firstly, we added the photo, which can help you understand the linking way better.
the linking way is right.
there are six terminals on the controller.
two for solar panel.
two for battery
two for DC appliances.

secondly, controller---- battery---inverter--- AC Family applinaces.
if you directly link inverter with controller, will cause the current shortage. had better not do that.

Would some mod please Nuke this SPAMMER. That is if there are any Mods left.

[rickoxo]

Yes minus some protection devices.

No and no. What you do not understand is a solar panel is a variable current source of unknown quantity. , not a constant voltage source like a battery.

Thanks for responding. I get that a solar panel is a variable current source, but my question is about the wiring. If you look at the wiring diagram I provided, the wires for the charge controller are attached to the same battery terminals where the inverter are attached to. So that makes the charge controller connected to the inverter directly, no? If my wiring diagram is wrong (i.e. that's not how I should set it up), please let me know.

But if that is the right way to wire it (minus a battery fuse?), then how does having a battery present avoid the problems of the charge controller giving power straight to the inverter?

[billvon]

But if that is the right way to wire it (minus a battery fuse?), then how does having a battery present avoid the problems of the charge controller giving power straight to the inverter?

?? It doesn't. When the solar panel output exactly matches the inverter, and the battery is fully charged, then the output of the panel goes directly to the inverter.

However that almost never happens. What usually happens is one of the following:

1) Solar is delivering less than the load. In that case the battery supplies the balance of the power.

2) Solar is delivering more than the load. In that case the battery absorbs the balance of the power.

3) Solar is delivering more AND the battery is fully charged. In that case the charge controller allows the panel voltage to rise, effectively "rejecting" the surplus power that would have come from the solar panels.

Without the battery the system would shut down the first time there was a transient load that exceeded the panel's output (or the first time there was a cloud.)

[rickoxo]

?? It doesn't. When the solar panel output exactly matches the inverter, and the battery is fully charged, then the output of the panel goes directly to the inverter.

However that almost never happens. What usually happens is one of the following:

1) Solar is delivering less than the load. In that case the battery supplies the balance of the power.

2) Solar is delivering more than the load. In that case the battery absorbs the balance of the power.

3) Solar is delivering more AND the battery is fully charged. In that case the charge controller allows the panel voltage to rise, effectively "rejecting" the surplus power that would have come from the solar panels.

Without the battery the system would shut down the first time there was a transient load that exceeded the panel's output (or the first time there was a cloud.)

Aaaah, so the charge controller monitors the battery status and the power demand of the inverter? That's pretty impressive. So why can't it do that without the battery? It would seem like it would be able to do exactly what you described in #3, and reject any surplus power, and match the power demand from the inverter?

One more question, so I get a battery, the panels charge during the day and the pump I have connected to the inverter pumps during the day. When the panels stop charging, the pump keeps going sucking power from the battery. What happens when the battery gets too low to power the pump? That's not a problem, I don't need it to run all night, I'm just wondering what happens? The inverter senses not enough power and shuts off?

Thanks for your help

[Sunking]

Aaaah, so the charge controller monitors the battery status and the power demand of the inverter? That's pretty impressive. So why can't it do that without the battery? It would seem like it would be able to do exactly what you described in #3, and reject any surplus power, and match the power demand from the inverter?

The charge controller is a simple voltage regulator designed to operate into the very low impedance of a battery, thus the voltage is very stable and constant.

One more question, so I get a battery, the panels charge during the day and the pump I have connected to the inverter pumps during the day. When the panels stop charging, the pump keeps going sucking power from the battery. What happens when the battery gets too low to power the pump?

What do you think happens?. You kill your your battery. Your inverter is made to do one thing, supply power when a device is connected to it demanding power. It will do so until you turn off the load device, or the battery voltage drops below it set cut-off voltage.

[billvon]

Aaaah, so the charge controller monitors the battery status and the power demand of the inverter?

Sort of. It ensures the battery's target voltages and currents are not exceeded and times the change of charge states for the battery.

So why can't it do that without the battery? It would seem like it would be able to do exactly what you described in #3, and reject any surplus power, and match the power demand from the inverter?

It can, if you add enough capacitance to provide a low AC impedance to the input of the inverter.

But again, such a system would be useless. Refrigerator tries to start? System shuts down and does not restart. Cloud comes by? System shuts down and does not restart. Since most people would not be happy with a system that runs only a few minutes per day, such systems are not widely used.

One more question, so I get a battery, the panels charge during the day and the pump I have connected to the inverter pumps during the day. When the panels stop charging, the pump keeps going sucking power from the battery. What happens when the battery gets too low to power the pump? That's not a problem, I don't need it to run all night, I'm just wondering what happens? The inverter senses not enough power and shuts off?

Yes, most inverters have a low voltage disconnect. This is more of an "emergency" shutdown than something you should rely on though. A few months of that and you'll destroy your batteries.

[Sunking]

It can, if you add enough capacitance to provide a low AC impedance to the input of the inverter.

But again, such a system would be useless. Refrigerator tries to start? System shuts down and does not restart. Cloud comes by? System shuts down and does not restart. Since most people would not be happy with a system that runs only a few minutes per day, such systems are not widely used.

That is what a battery does except batteries have much higher capacity.

[rickoxo]

Sort of. It ensures the battery's target voltages and currents are not exceeded and times the change of charge states for the battery.

It can, if you add enough capacitance to provide a low AC impedance to the input of the inverter.

But again, such a system would be useless. Refrigerator tries to start? System shuts down and does not restart. Cloud comes by? System shuts down and does not restart. Since most people would not be happy with a system that runs only a few minutes per day, such systems are not widely used.

Yes, most inverters have a low voltage disconnect. This is more of an "emergency" shutdown than something you should rely on though. A few months of that and you'll destroy your batteries.

Ok, so my system is small (60 watts) and I'm trying to power a small pump (320 gallons/hour, it says .35Amp, but that seems crazy low) and a small air pump for an outdoor pond. Nothing else, nothing kicking on or off, but clouds do come by and I'd like the system to work/charge during the day and work/drain during the night. Should I shut the system off at some time at night before it has a chance to fully discharge? I take it from what you're saying, fully discharging batteries is not good. I was reading that a good battery for a system like this is a 12V golf cart battery (or 2 6 volts tied together).

I've used solar for years to run DC pumps that just pump as much as they have power, this is my first try at going AC and adding a battery. Any suggestions would be greatly appreciated.

[Chris M]

Also Newbie with some understanding but still needing to confirm

Hi, Yes the solar voltage does fluctuate. The battery will help to regulate the voltage. From what I understand and please correct if wrong is that the load on the battery will affect the charge controller. But I too have the same question and am at the phase of testing my inverter and battery bank. I understand the connection point to the inverter is also the same as the charger. Can anyone else confirm with diagram? Thanks to all and again Im new so pls be kind... thnks

Here's a picture of a basic wiring diagram for my solar setup:

[ATTACH=CONFIG]2220[/ATTACH]

First question, is this wiring diagram correct? If it is, here's what I don't get. The charge controller connects to the battery via the battery terminals. The inverter connects to the battery the same way, via the terminals. So doesn't that mean that the charge controller is directly wired to the inverter? Can you just skip the battery?

So, what happens if it's solar noon, the panel is producing maximum voltage, the battery is full and the inverter has something plugged in but it only needs a little power? I'm sure there's something I'm not understanding, but it seems like because the charge converter and the inverter are both connected at the battery terminals, that they end up being directly connected as well. Maybe if the battery was low on charge, some of the power could get sucked into the battery first before going along to the inverter, but what if the battery is fully charged?

Thanks,

Rick

[billvon]

Ok, so my system is small (60 watts) and I'm trying to power a small pump (320 gallons/hour, it says .35Amp, but that seems crazy low) and a small air pump for an outdoor pond. Nothing else, nothing kicking on or off, but clouds do come by and I'd like the system to work/charge during the day and work/drain during the night. Should I shut the system off at some time at night before it has a chance to fully discharge? I take it from what you're saying, fully discharging batteries is not good.

Correct.

I was reading that a good battery for a system like this is a 12V golf cart battery (or 2 6 volts tied together).

Yes, T-105's are reasonable "first" batteries for a project like this. They are cheap and fairly robust, and thus will both tolerate some abuse and not cost you too much when they get too abused.

I've used solar for years to run DC pumps that just pump as much as they have power, this is my first try at going AC and adding a battery. Any suggestions would be greatly appreciated.

If you want to terminate operation after X hours without sun, there are several charge controllers (often called "lighting controllers") that will do this for you. If your drain is significant you may need the lighting controller to drive a DC relay that switches your load off. You can set it to run 1 hour after sunset, 2 hours etc. (Morningstar Sunlight is an example of this.)

If you want to terminate operation when the battery gets low, you can use something like a C40 charge controller in LVD mode. Set it fairly high (12.2 volts or so, depends on load) and the system will disconnect when the battery gets to that level. That way the system runs as long as there's power while not letting the battery get too low.

You can also use an inverter with a programmable LVD but most of the ones that I've seen that are programmable are also pricey.

Question - why do you want to switch to AC? For your purposes DC might be easier.

[sapparamesh]

HI....

Hi... Guys... I'm new to this forum and i have some doubts....

Suppose.... Its Broad Daylight and Pannels are Giving their Max Output...
The Mains (Grid Supply) to the Inverter is in OFF.. But Load to the inverter is in on state..
In the Above Condition:
1.If the battery is not in fully charged condition... Solar Pannels will supply the power for both Load and Battery (provided the pannels meet power requirement of both).... Am i right with this statement....??

2.If Battery is fully charged, how exactly will the Charge Controller controls the current flowing through the battery (i.e. seeing the battery is not over charged) and the inverter (supply current to the Load). I'm asking this Q coz Both Battery and Inverter are connected in Parallel...

I'll be very greatfull if someone responds....
Than Q.

[Sunking]

1.If the battery is not in fully charged condition... Solar Pannels will supply the power for both Load and Battery (provided the pannels meet power requirement of both).... Am i right with this statement....??

Maybe, maybe not. If the demand of the discharged battery and the connected load exceed what the panel is generating, the difference (loss) is being supplied by the battery, thus discharging the battery.

2.If Battery is fully charged, how exactly will the Charge Controller controls the current flowing through the battery (i.e. seeing the battery is not over charged) and the inverter (supply current to the Load). I'm asking this Q coz Both Battery and Inverter are connected in Parallel...

The CC will be in a float mode and at that point is a voltage source. All power required for the load comes directly from the panels. The battery is just sitting there not requiring any current or supplying any current. Example if you have a 200 watt panel that has enough sun to supply up to 200 watts, and th eload is demanding 100 watts, the panel only produces 100 watts. The other 100 watts is not being used or wasted.