MEP803A low output for solar system backup

[jrhunter]

I have a MEP803A that charges my batteries when there is no solar. I have 24-300w panels that will put out more than their rated capacity of 7200 watts. I have Schnieder solar contollers, inverters and chargers. When my MEP803A turns on, it rarely exceeds 5500 watts of input into this system. It is installed at 5800' in Montana, so I know there is some altitude derating taking place. I just can't figure out why the genset won't produce equal power to the panels. Any ideas? Thanks.

 

[Coug]

If it's not loading down the generator, then I'd say it's likely that the bottleneck here is your charge controller only asking for 5500 watts of power, rather than the generator not producing the power. Just because the solar panels are capable of producing more than 7200 watts doesn't always mean that it's all being used.

Is the generator getting bogged down and straining to produce this power, or is it just chugging along like normal?

 

[DieselAddict]

How is the generator connected to the system? Is the generator failing to put out its full rating or is the system not demanding enough from the generator?

I have a XW6848 running my system and on that unit generator load is programmable in the inverter. There are also settings such as minimum voltage that can affect how much power is drawn from the generator.

I don't think we know enough about your situation to provide better input.

 

[jrhunter]

If it's not loading down the generator, then I'd say it's likely that the bottleneck here is your charge controller only asking for 5500 watts of power, rather than the generator not producing the power. Just because the solar panels are capable of producing more than 7200 watts doesn't always mean that it's all being used.

Is the generator getting bogged down and straining to produce this power, or is it just chugging along like normal?

It seems to be chugging along without effort. According to my system, the system seems to be using all the output for loads and battery charging.

How is the generator connected to the system? Is the generator failing to put out its full rating or is the system not demanding enough from the generator?

I have a XW6848 running my system and on that unit generator load is programmable in the inverter. There are also settings such as minimum voltage that can affect how much power is drawn from the generator.

I don't think we know enough about your situation to provide better input.

 

[jrhunter]

It seems to be chugging along without effort. According to my system, the system seems to be using all the output for loads and battery charging.

The generator has an auto start and the power leads are connected directly to the power distribution panel. When the system is close to a full charge the generator and solar output is reduced to what ever level is required to charge the batteries. When the generator starts it takes about 3 minutes to start supplying power to the power distribution panel. The generator does not really speed up when the output begins, but I can tell the generator is under a little load. I don't know if it is operating at 1800 rpms, but it never seems to idle down when the generator is shutting down. Could I have a problem with the governor? Thank you.

How is the generator connected to the system? Is the generator failing to put out its full rating or is the system not demanding enough from the generator?

I have a XW6848 running my system and on that unit generator load is programmable in the inverter. There are also settings such as minimum voltage that can affect how much power is drawn from the generator.

I don't think we know enough about your situation to provide better input.

 

[Coug]

These generators don't change speed when running. Or at least not more than a very slight amount. It's not enough to really notice compared to the increasing amount of noise from the extra work the gen is doing with a heavy load. The volume gets louder, the tone deepens a little, but the frequency of the noise doesn't do much.

The 3 minute wait at startup is probably a function built into your charge controller to allow the generator to warm up a little before being put under a load. There will also be a cool down period at the end where the controller lets the generator run for a few minutes to make sure it's cooled off enough to safely shut down.

If the generator is chugging along not dropping in power (have you looked at the HZ meter? multiple that x30 to get engine RPMs) then the generator is doing it's job properly.

Basic lesson in generators.
The generator head will put out the amount of power the load is trying to draw. If the load is trying to draw too much power, then one of two things will happen. Either the engine bogs down because it doesn't produce enough power to keep the electromagnetic fields in the generator spinning against the resisting field created by the load drawing power, or somewhere in the system a wire is going to get hot from too much amperage going through it and you'll melt that wire, creating an open circuit through which no power will flow, or two wires will melt together through the insulation around the wires resulting in a short circuit.

If your unit is producing the required voltage, and is running at the proper speed to produce 60hz power, then what you are talking about is not a problem with the generator. The generator is likely functioning how it's supposed to.



Reading through the manual for the Conext SW charger/inverter it looks like AC input is limited to a 30 amp breaker, or 7200 watts. You never specified what model of equipment you're running, so I'll go with this one for now.

(When you say 5500 watts input, does that mean 5500 watts total, or is that 5500 watts going to the batteries to charge them? If it's 5500 total and not just to the batteries, you can disregard the next part, as it's mostly speculation about what could be occurring)

So maximum your system (if it's this model) would be able to draw is 7000 watts or so before tripping the breaker. That 7kw is going to go both to charging the batteries and bypass the inverter to output to your house/load as well. If your house/loads are drawing 1500 watts of power, then the battery input at that point will be 5500 watts or less. It doesn't convert all the generator power into DC power to charge the batteries just to convert it back to AC again.

 

[DieselAddict]

The generator has an auto start and the power leads are connected directly to the power distribution panel. When the system is close to a full charge the generator and solar output is reduced to what ever level is required to charge the batteries. When the generator starts it takes about 3 minutes to start supplying power to the power distribution panel. The generator does not really speed up when the output begins, but I can tell the generator is under a little load. I don't know if it is operating at 1800 rpms, but it never seems to idle down when the generator is shutting down. Could I have a problem with the governor? Thank you.

Can you list the model numbers of the equipment?

These are constant speed generators. They should start and run continuously at 1800 RPM.

 

[csheath]

You need to disconnect the generator from the system and load test it. Keep an eye in Craigslist for a free or cheap electric range.

What voltage do you have it set for?

 

[jrhunter]

These generators don't change speed when running. Or at least not more than a very slight amount. It's not enough to really notice compared to the increasing amount of noise from the extra work the gen is doing with a heavy load. The volume gets louder, the tone deepens a little, but the frequency of the noise doesn't do much.

The 3 minute wait at startup is probably a function built into your charge controller to allow the generator to warm up a little before being put under a load. There will also be a cool down period at the end where the controller lets the generator run for a few minutes to make sure it's cooled off enough to safely shut down.

If the generator is chugging along not dropping in power (have you looked at the HZ meter? multiple that x30 to get engine RPMs) then the generator is doing it's job properly.

Basic lesson in generators.
The generator head will put out the amount of power the load is trying to draw. If the load is trying to draw too much power, then one of two things will happen. Either the engine bogs down because it doesn't produce enough power to keep the electromagnetic fields in the generator spinning against the resisting field created by the load drawing power, or somewhere in the system a wire is going to get hot from too much amperage going through it and you'll melt that wire, creating an open circuit through which no power will flow, or two wires will melt together through the insulation around the wires resulting in a short circuit.

If your unit is producing the required voltage, and is running at the proper speed to produce 60hz power, then what you are talking about is not a problem with the generator. The generator is likely functioning how it's supposed to.



Reading through the manual for the Conext SW charger/inverter it looks like AC input is limited to a 30 amp breaker, or 7200 watts. You never specified what model of equipment you're running, so I'll go with this one for now.

(When you say 5500 watts input, does that mean 5500 watts total, or is that 5500 watts going to the batteries to charge them? If it's 5500 total and not just to the batteries, you can disregard the next part, as it's mostly speculation about what could be occurring)

So maximum your system (if it's this model) would be able to draw is 7000 watts or so before tripping the breaker. That 7kw is going to go both to charging the batteries and bypass the inverter to output to your house/load as well. If your house/loads are drawing 1500 watts of power, then the battery input at that point will be 5500 watts or less. It doesn't convert all the generator power into DC power to charge the batteries just to convert it back to AC again.

 

[jrhunter]

These generators don't change speed when running. Or at least not more than a very slight amount. It's not enough to really notice compared to the increasing amount of noise from the extra work the gen is doing with a heavy load. The volume gets louder, the tone deepens a little, but the frequency of the noise doesn't do much.

The 3 minute wait at startup is probably a function built into your charge controller to allow the generator to warm up a little before being put under a load. There will also be a cool down period at the end where the controller lets the generator run for a few minutes to make sure it's cooled off enough to safely shut down.

If the generator is chugging along not dropping in power (have you looked at the HZ meter? multiple that x30 to get engine RPMs) then the generator is doing it's job properly.

Basic lesson in generators.
The generator head will put out the amount of power the load is trying to draw. If the load is trying to draw too much power, then one of two things will happen. Either the engine bogs down because it doesn't produce enough power to keep the electromagnetic fields in the generator spinning against the resisting field created by the load drawing power, or somewhere in the system a wire is going to get hot from too much amperage going through it and you'll melt that wire, creating an open circuit through which no power will flow, or two wires will melt together through the insulation around the wires resulting in a short circuit.

If your unit is producing the required voltage, and is running at the proper speed to produce 60hz power, then what you are talking about is not a problem with the generator. The generator is likely functioning how it's supposed to.



Reading through the manual for the Conext SW charger/inverter it looks like AC input is limited to a 30 amp breaker, or 7200 watts. You never specified what model of equipment you're running, so I'll go with this one for now.

(When you say 5500 watts input, does that mean 5500 watts total, or is that 5500 watts going to the batteries to charge them? If it's 5500 total and not just to the batteries, you can disregard the next part, as it's mostly speculation about what could be occurring)

So maximum your system (if it's this model) would be able to draw is 7000 watts or so before tripping the breaker. That 7kw is going to go both to charging the batteries and bypass the inverter to output to your house/load as well. If your house/loads are drawing 1500 watts of power, then the battery input at that point will be 5500 watts or less. It doesn't convert all the generator power into DC power to charge the batteries just to convert it back to AC again.

These generators don't change speed when running. Or at least not more than a very slight amount. It's not enough to really notice compared to the increasing amount of noise from the extra work the gen is doing with a heavy load. The volume gets louder, the tone deepens a little, but the frequency of the noise doesn't do much.

The 3 minute wait at startup is probably a function built into your charge controller to allow the generator to warm up a little before being put under a load. There will also be a cool down period at the end where the controller lets the generator run for a few minutes to make sure it's cooled off enough to safely shut down.

If the generator is chugging along not dropping in power (have you looked at the HZ meter? multiple that x30 to get engine RPMs) then the generator is doing it's job properly.

Basic lesson in generators.
The generator head will put out the amount of power the load is trying to draw. If the load is trying to draw too much power, then one of two things will happen. Either the engine bogs down because it doesn't produce enough power to keep the electromagnetic fields in the generator spinning against the resisting field created by the load drawing power, or somewhere in the system a wire is going to get hot from too much amperage going through it and you'll melt that wire, creating an open circuit through which no power will flow, or two wires will melt together through the insulation around the wires resulting in a short circuit.

If your unit is producing the required voltage, and is running at the proper speed to produce 60hz power, then what you are talking about is not a problem with the generator. The generator is likely functioning how it's supposed to.



Reading through the manual for the Conext SW charger/inverter it looks like AC input is limited to a 30 amp breaker, or 7200 watts. You never specified what model of equipment you're running, so I'll go with this one for now.

(When you say 5500 watts input, does that mean 5500 watts total, or is that 5500 watts going to the batteries to charge them? If it's 5500 total and not just to the batteries, you can disregard the next part, as it's mostly speculation about what could be occurring)

So maximum your system (if it's this model) would be able to draw is 7000 watts or so before tripping the breaker. That 7kw is going to go both to charging the batteries and bypass the inverter to output to your house/load as well. If your house/loads are drawing 1500 watts of power, then the battery input at that point will be 5500 watts or less. It doesn't convert all the generator power into DC power to charge the batteries just to convert it back to AC again.

This is really good information. I have attached 3 screen shots of my Connext Combox demonstrating the issue. The first photo shows 1880 watts of solar input, and 5168 watts of generator input. The batteries are showing a 69% state of charge and loads are 1051.
The next picture shows 2706 watts of solar, and 5193 watts of generator input. There is 1056 watts of load.
The last photo is with the solar system disconnected. The generator is purducing 5282 watts with the total load of 990 watts.
As you can see by the generator numbers, there is little difference between all 3 readings. I hope I explained this correctly. I am stumped why the generator output does not increase. Thank you.

 

[DieselAddict]

I think we have gotten down to the root of what is going on. The Schneider inverter will limit the power draw on the generator input to 80% of the configured breaker size (60A) while charging. It uses the charging current as the variable to limit the power draw on the generator input. As an example if the loads on the inverter are 10 amps that leaves 38 amps to charge the batteries.

We talked on the phone and went over the numbers the inverter is reporting. It looks like the software current limit that is exactly whats happening here. The generator is providing power to the loads in the house directly (as a pass-through on the inverter) and the inverter is taking the excess power between the load amps and ~48a to charge the batteries.

According to the documentation for the inverter everything looks to be working as its supposed to.

 

[Coug]

Generator is putting out power.
As long as the power is within the input requirements of the inverter/charger, then the generator is good. Considering it's being converted to DC power to charge the batteries, it shouldn't matter if the volts or frequency is a little off.
The ONLY thing that might possibly be the generator limiting this is if the frequency is too low, and the inverter/charger is refusing to draw power below that point. Without physically seeing the generator it's hard for me to say.
As for voltage, the AVR takes care of making the voltage stay where you set it, even if the machine

When the charger/inverter is pulling 5000 watts from the generator, have you looked at the frequency meter on it? If the meter is below 59hz, you might want to bump it up just a little and see if that changes anything. At half load the frequency should be right at 60hz. With no load on the generator it will read up to 62.5hz potentially, but more likely in the 61 or so area.

Generator only controls the voltage and frequency. After that the inverter/charger is in control. The number of Watts drawn by the inverter/charger is controlled by the inverter/charger, and NOT the generator.
My guess would be there is some type of setting in the controller to limit it below the breaker.
(just as I was typing this, DieselAddict made his post)