Solar system bust

[AndreandElisha]

We recently had 3 385 watt solar panels installed along with a victron multiplus 3000 watt inverter. Before, we had battery power for lights and used the generator for 110 power if not plugged in. Batteries held a decent charge and charged fairly quickly with the generator.
Now, when we have sun we can run basically everything in the RV except the AC. But as soon as the sun goes down, we have almost zero battery power. We can no longer charge the batteries with the generator, we have to actually run the RV engine! And we still have to run the generator if we want any kind of power. And I am talking 1 reading light. Everything else is completely shut off. Microwave unplugged, inverter off, converter unplugged, we don't even leave the water pump on.
We have a 2004 Georgetown XL 346 which has the chassis battery and 2 12v house batteries under the stairs. We would like to increase our house batteries but not sure where to put them. Plus, I don't feel that adding more batteries is going to fix the problem.

 

[flyboy013]

It sounds like the solar panels are doing a great running everything in the coach, but perhaps they are not charging the batteries with that solar power. Have you put a voltmeter on the batteries to get a reading while you have solar power? It also sounds like the generator isn't charging the batteries. Sounds like the batteries are not connected. Perhaps a shutoff switch at the battery?

 

[TJ&LadyDi]

It does sound like the solar panels are not charging the batteries. I would go back to the installer with the problem. I'm guessing something has not been configured correctly.

Another thought is how old are your batteries? Is it possible that they are bad and not holding a charge?

TJ

 

[Chuggs]

There could be lots of things going on. The quantity and type of batteries you have is truly the heart of an off grid system. How many aH of storage do you have? Did the installation manual for that 3000w inverter really recommend 2 twelve volt batteries? Were the charge parameters set properly? For example...you have enough solar to be pushing 80 amps or more. If not set up properly...this will cook your two batteries.

I would focus first on making sure you understand the inverter/Charger, and Solar Charge controller...how to adjust parameters for a specific battery type. Then...purchase some batteries designed for the demands of deep cycles with adequate storage to meet your needs for more than just overnight. I ran a test on my coach...I have eight 6v deep cycle golf cart type batteries. They can run the parasitic drains, misc router...and other items as well as our residential refrigerator for about 40 hours. That isn’t to the point of the batteries being dead...this is to the 50% point. Depending on battery chemistry, using more than this penalizes you with shortened battery life.

If you said you had 1000w inverter for charging tablets, and phone, and you ran led lights...two 12v batteries might be okay. Running a 3000w inverter...you must be doing more than phones with that. Fridge? Microwave? Coffee Maker? These can pull quite a bit of amperage. Something that you might not have considered is battery efficiency. Lead acid batteries are good at giving back the energy they stored at a 20hr rate. So, if you had a 100aH battery... over 20hours...of 5A drain. 5A at 12.6v would be 63 watts... Hmmm, so 63 isn’t close to 3000w. Let‘s say you have two of these batteries. 126w...getting closer, but still no where close to 3000w. Don’t worry...you’re not alone. Most of us are drawing more than the C/20 rate from our cells. The trade off comes with energy loss from Peukert effect. As you increase the rate of discharge...more and more energy is lost due to thermal loss ...thus due to the batteries internal resistance. So if you thought of getting 100ah out of the battery...it just won’t happen when your discharge rates are high. I have seen over 165Amps going to my 3000 watt inverter at times. What can you do? You have to spread it out over multiple batteries. Having more batteries is more than just giving you more aH of storage...it means spreading out the load so that each battery is discharged at a slower rate. At this slower rate...you have fewer aH of storage lost to heat energy.

If the previous replies are correct...and the batteries aren’t connected to your solar...well that’s a sign your installer isn’t very good at his job. To me, that is already evident...he sold you a system that is that large...and didn’t explain to you how poorly designed it was due to the fact that two batteries aren’t going to meet your needs. I also think the batteries could have been damaged, if they were connected, but not charged with the proper amperage. Lifeline AGMs and Lithium batteries are about the only ones capable of very high charging amperages. If you have flooded lead acid batteries...they will boil off at those high rates. 80A of charge would be more appropriate for 800aH worth of batteries.

That‘s a really nice solar panel array, and inverter....but they simply need more storage, and good quality storage.

 

[Jim]

We recently had 3 385 watt solar panels installed along with a victron multiplus 3000 watt inverter. Before, we had battery power for lights and used the generator for 110 power if not plugged in. Batteries held a decent charge and charged fairly quickly with the generator.
Now, when we have sun we can run basically everything in the RV except the AC. But as soon as the sun goes down, we have almost zero battery power.

I have a stupid question.

It seems everyone feels the solar panels are doing a great job running everything. But how do we know that the solar panels are doing the work? If the batteries are dead at the end of the day, maybe it's actually the batteries that are doing the work and the solar isn't getting to the batteries.

Like I said, probably a stupid question.

 

[TJ&LadyDi]

I have a stupid question.

It seems everyone feels the solar panels are doing a great job running everything. But how do we know that the solar panels are doing the work? If the batteries are dead at the end of the day, maybe it's actually the batteries that are doing the work and the solar isn't getting to the batteries.

Like I said, probably a stupid question.

There aren't any "stupid questions" on RVF @Jim; just questions that need answers. And, your question is actually a very good one. I'm hoping some of the solar gurus here can provide a relatively simple method of how to measure whether the solar panels are actually performing as designed.

TJ

 

[flyboy013]

You stated that you “can no longer charge the batteries with the generator, we have to actually run the RV engine! And we still have to run the generator if we want any kind of power.”

Sound like the generator is outputting 120V which is feeding the transfer switch and then 120V circuits including the inverter. I assume you can operate 12V devices (lights, etc) with the generator running. If so, the charger is working. If not then there is a cut off switch or fuse limiting the invert in providing 12V to the coach.
I’m assuming your batteries are basically dead and the only way to get power is via solar, generator, or as you have stated the engine alternator (which would also mean that the charge bridge is engaged providing the alternator power to the coach systems.

You really need to get a voltage reading at you coach batteries, ideally when you have power going to them (via solar/charge controller, or generator) AND without power feeding the batteries. I’m guessing that the voltages will be the same, and you will find that the generated power isn’t feeding the batteries. Perhaps a blown inline fuses, a switch between the batteries and inverter/solar controller is turned off, or a wire is disconnected.

You need to trace the power. Once we know what the voltage is at the batteries (with solar or generator running), we can help isolate where the disconnect/issue exists.

BTW - I’m no solar or power expert, but I am an engineer and my suggestion are based on occupational troubleshooting techniques. Others on this forum have much more expertise with solar systems.

 

[Chuggs]

There is a quick way, and a more detailed way to see if solar is working.

Lead acid batteries...as an example...if not being charged...are approx. 12.6v. If you have a voltage reading from the house batteries...if they say 12.6 or less...solar isn't doing anything. If you see a higher voltage, something other than the batteries are at play. The solar charge controller will usually do a three stage charge...BULK, ABSORB, and FLOAT. I have my controller set to Bulk Charge at 90A (Thats for 928aH bank)...it will push up to that many amps until my absorb voltage is reached, then switches to constant voltage of 14.51v. It holds this until the amperage tapers off to the tail current draw...then drops down to 13.43v to float, until sundown. So I can usually guess what solar is doing just by comparing the voltage reading of the batteries to what I expect my charge controller to do.

Now, the more accurate method is to read the controllers display. It should tell you how many watts are being output in real time, and I highly recommend a shunt based battery monitor. The battery monitor can display at a glance how many amps are either going IN or OUT...and what the battery charge state is (SOC) expressed in percentage of full.

It only takes about 150watts to maintain float voltage on my coach...so, if I see the wattage output is up around 900 or more...I know my wife probably has something in the microwave.

It takes time to learn the nuances of your system. There isn’t an overnight...know everything. It is a series of puzzling things, that you endeavor to explain logically. The more you convert these puzzling moments into eureka events....the more you will understand solar.

So, don't get frustrated....these puzzles are part of the growth of your knowledge base.

 

[TJ&LadyDi]

Good explanation, @Chuggs; thanks for helping fill in one of the many gaps in my knowledge base.

TJ

 

[AndreandElisha]

You stated that you “can no longer charge the batteries with the generator, we have to actually run the RV engine! And we still have to run the generator if we want any kind of power.”

Sound like the generator is outputting 120V which is feeding the transfer switch and then 120V circuits including the inverter. I assume you can operate 12V devices (lights, etc) with the generator running. If so, the charger is working. If not then there is a cut off switch or fuse limiting the invert in providing 12V to the coach.
I’m assuming your batteries are basically dead and the only way to get power is via solar, generator, or as you have stated the engine alternator (which would also mean that the charge bridge is engaged providing the alternator power to the coach systems.

You really need to get a voltage reading at you coach batteries, ideally when you have power going to them (via solar/charge controller, or generator) AND without power feeding the batteries. I’m guessing that the voltages will be the same, and you will find that the generated power isn’t feeding the batteries. Perhaps a blown inline fuses, a switch between the batteries and inverter/solar controller is turned off, or a wire is disconnected.

You need to trace the power. Once we know what the voltage is at the batteries (with solar or generator running), we can help isolate where the disconnect/issue exists.

BTW - I’m no solar or power expert, but I am an engineer and my suggestion are based on occupational troubleshooting techniques. Others on this forum have much more expertise with solar systems.

Our solar installer is now 1200 miles away but is helping us troubleshoot by chat. Unfortunately neither of us are electrically inclined.
We figured out how to charge our batteries with the generator. We have a converter that we were told to leave unplugged unless plugged into shore power. However, once the converter was plugged in, we were able to charge the batteries with the generator up to about 13.3.