200w solar system expectations...

[Rednecktek]

OK, so your controller is a PWM so realistically you will not see more than 75-ish watts out of it, but in direct clear sun each panel should be putting out about 5a. The controller is taking that 20v the panel is producing and cutting it down to the 14v the batteries want.

That is normal for a PWM controller.

What is NOT normal is that it's cutting it down to 12.6v which is "Almost Dead" for a battery, and only putting in 2.2a with 3 panels connected up.
Things to poke at:
1: Check the Batt+ and Batt- terminals with a meter, see what the voltage there is, it Should be about 14v give or take. If not, your SCC isn't doing its job.

2: Unplug and test each panel one at a time. If one panel is bad it could be nerfing the others. If you get about the same amperage on all 3 individually (3a for example) and then again when together (still 3a) then your SCC is shot. If one or more shows 0a in good sun then there's more testing that can be done.

3: I would HIGHLY recommend getting a proper MPPT controller. Even if the PWM is working perfectly, you're losing 25% of your panel's power Per Panel so best case you have effectively 3x 75w panels capability. You don't need a Victron or Outback, an EPEver or HQST or Rich Solar would be great, in a pinch PowMr will turn PV power into battery power just fine. If you can swing it, get a larger SCC than you need so you can grow into it in the future. Pro Tip: If it has USB ports on it, it's not MPPT, it's a dirty, dirty LIAR!

4: Lift up your panels! As a rule-of-thumb your panels should be at your latitude for best general year-round performance. If your panels are flat you're going to take another 30+% hit on performance. As an example, my camp is at 44deg N and change so I cut my frames at a 45deg because it's easy on the saw. They Should be tilted depending on the time of year but it's close enough to get real performance out of them. You can go outside at noon and point them directly at the sun and that's going to be about perfect.

EcoWorthy is pretty much the bottom of the barrel for quality so you're starting out at a significant disadvantage right out the gate. Add in that it's PWM and that's another big hit.

So let's add it all up on the napkin math here:
100w panel - 15% marketing factor = 85w
85w - 25% PWM inefficiency = 63.75w
63.75w panel - 30% for laying flat = 45w
45w panel * 3 panels = 135w of usable power, * 4 hours of sun = 535w per day of generation
135w / 14v = 9.5a that you SHOULD be seeing out of your SCC, not 2
So best case scenario you're almost breaking even on average.

IF you get a decent MPPT controller and get your panels tilted right napkin math:
100w panel - 15% marketing factor = 85w
85w - 5% cheap MPPT inefficiency = 80.75w
80.75w panel at the right angle = 80.75w
80.75w * 3 panels = 242w * 4 hours per day of sun = 969Wh
242w / 14v = 17.3a, or almost DOUBLE what your current setup can do.

Just for giggles and perspective, let's do "Perfect World" napkin math:
100w Panel * 3 = 300w
300w * 4 hours of sun = 1200Wh a day
300w / 14v = 21.4a to the batteries

Does that all make sense?

Did you ever find the No Load Draw for your inverter?

 

[crossy]

Just for giggles and perspective, let's do "Perfect World" napkin math:
100w Panel * 3 = 300w
300w * 4 hours of sun = 1200Wh a day
300w / 14v = 21.4a to the batteries

For a splash of perspective, from our real-world system.

Here in sunny Thailand 300W worth of panels will generate, on average, 1kWh per day. Some days much better, other days rather less good (OK total carp!).

Right now, we are getting about 40kWh per day from our 10kWP system, I expect that we will be down to 10kWh when the rain really sets in

 

[MichaelK]

As RNT mentions, what you've got is a PMW controller, even if they said it was MPPT when you bought it. There are a lot of fake products out there. A PMW controller only controls the amps going into the battery, so any voltage above the 12.6V the battery wants is basically wasted.

PMW is OK for the smallest of systems, but I think the breakeven point is around 300W or so. Above 300W, you save money buying the more expensive MPPT controllers, because they allow you to use much cheaper/W grid-tie panels.

If you switched right now, I think you'd see about a 40% increase in amps going into the batteries. If you decide to get more panels, then definately get a better controller. BTW, MPPT will allow you to wire all your panels in series, which will also get another modest gain in power due to losses via voltage drop.

 

[Rednecktek]

BTW, MPPT will allow you to wire all your panels in series, which will also get another modest gain in power due to losses via voltage drop.

As well as potentially getting charging at lower light levels like early morning, later afternoon, and slightly overcast. The panels in series would hit operating voltages much sooner and hold onto them much later.

 

[MichaelK]

As well as potentially getting charging at lower light levels like early morning, later afternoon, and slightly overcast. The panels in series would hit operating voltages much sooner and hold onto them much later.

Actually, I see this myself early in the morning. My habit is to walk out to the utility room, coffee in hand, and watch the charge controller right at sunrise. Tuning in to the "electricity channel". My array's nominal voltage is ~118VDC, but right around sunrise, I see voltages as low as 98V. Once the batteries are fully charged though, I see the voltage bumping to to ~125VDC. So, that's a 27V spread from morning to afternoon.

 

[Entwicklung34]

If it's on your controller then 1a is only 1a @ the 12v of your batteries, or 12w. In a perfect world you should be seeing about 10a out of your controller if it's PWM, 16a if it's a nicer MPPT. Pro Tip: If there are USB ports on the front/side of your controller, it's PWM 99% of the time.


That would be 0.6w @ 12v or 7.2w. Something is wrong or you live near me where the weather is horrible.

Even in a perfect world with 200w of panel and 5 full hours of sun you're not quite getting 2 days of charge. With 3 hours of sun that's only 600wh in a perfect world. If your controller is a cheaper PWM figure you're only getting about 75% of that 200w, or 150w per hour, 450Wh per day.

I don't see your inverter in your power list. If you look up the make & model you should find an entry for "No Load Draw" or "Standby Draw" or something like that. That's how much the inverter uses just to exist so take that number and multiply it by 24hrs and add that to your daily consumption.

You should think of Watts like Grams, it takes a lot to do much and nobody gets ripped by lifting 5000g weights.

Ahhh it's 0.6amps I meant going in! Today is 2.2amps in and it's overcast so that makes more sense - sorry!

OK, so your controller is a PWM so realistically you will not see more than 75-ish watts out of it, but in direct clear sun each panel should be putting out about 5a. The controller is taking that 20v the panel is producing and cutting it down to the 14v the batteries want.

That is normal for a PWM controller.

What is NOT normal is that it's cutting it down to 12.6v which is "Almost Dead" for a battery, and only putting in 2.2a with 3 panels connected up.
Things to poke at:
1: Check the Batt+ and Batt- terminals with a meter, see what the voltage there is, it Should be about 14v give or take. If not, your SCC isn't doing its job.

2: Unplug and test each panel one at a time. If one panel is bad it could be nerfing the others. If you get about the same amperage on all 3 individually (3a for example) and then again when together (still 3a) then your SCC is shot. If one or more shows 0a in good sun then there's more testing that can be done.

3: I would HIGHLY recommend getting a proper MPPT controller. Even if the PWM is working perfectly, you're losing 25% of your panel's power Per Panel so best case you have effectively 3x 75w panels capability. You don't need a Victron or Outback, an EPEver or HQST or Rich Solar would be great, in a pinch PowMr will turn PV power into battery power just fine. If you can swing it, get a larger SCC than you need so you can grow into it in the future. Pro Tip: If it has USB ports on it, it's not MPPT, it's a dirty, dirty LIAR!

4: Lift up your panels! As a rule-of-thumb your panels should be at your latitude for best general year-round performance. If your panels are flat you're going to take another 30+% hit on performance. As an example, my camp is at 44deg N and change so I cut my frames at a 45deg because it's easy on the saw. They Should be tilted depending on the time of year but it's close enough to get real performance out of them. You can go outside at noon and point them directly at the sun and that's going to be about perfect.

EcoWorthy is pretty much the bottom of the barrel for quality so you're starting out at a significant disadvantage right out the gate. Add in that it's PWM and that's another big hit.

So let's add it all up on the napkin math here:
100w panel - 15% marketing factor = 85w
85w - 25% PWM inefficiency = 63.75w
63.75w panel - 30% for laying flat = 45w
45w panel * 3 panels = 135w of usable power, * 4 hours of sun = 535w per day of generation
135w / 14v = 9.5a that you SHOULD be seeing out of your SCC, not 2
So best case scenario you're almost breaking even on average.

IF you get a decent MPPT controller and get your panels tilted right napkin math:
100w panel - 15% marketing factor = 85w
85w - 5% cheap MPPT inefficiency = 80.75w
80.75w panel at the right angle = 80.75w
80.75w * 3 panels = 242w * 4 hours per day of sun = 969Wh
242w / 14v = 17.3a, or almost DOUBLE what your current setup can do.

Just for giggles and perspective, let's do "Perfect World" napkin math:
100w Panel * 3 = 300w
300w * 4 hours of sun = 1200Wh a day
300w / 14v = 21.4a to the batteries

Does that all make sense?

Did you ever find the No Load Draw for your inverter?

This is brilliant, thank you!

I'll get the multimeter out and check out the numbers across the panel/s and battery. The battery has been charged up to 14.4v before but I think my wife drained it with her hair dryer which made the SCC cut out the supply and it hasn't fully charged since I feel. Will check what it's on tonight as it does seem to have increased today. From your figures I'm way down on amps going in... Devastating!

I'm guessing it might just need a little time with all the inefficiency you outlined to get the battery back up to 14.4v...

What you've said there makes perfect sense and I will have to look at upgrading the charge controller if I want the system to be worthwhile! I can't believe that the charge controller that came with the kit is so poor... I never expected losses from the charge controller. It's a bit gutting because I've invested so much already to get going and now I'm looking at least at another £100 by the looks of it! Any thoughts on this one? https://www.ebay.co.uk/itm/22456797...ar=523359359694&widget_ver=artemis&media=COPY


Also, I looked through the booklet that came with the charge controller, I couldn't find anything related to standby power drain. I will do some online research for that.

Quick question - I have inline fuses on the positives of each panel and I know I need one on the positive cable from the batter to the charge controller... I just need to know what amp size I would need - can anybody help me with the calcs you use to figure that out please?

Thanks so much for all info and advice so far - it is very much appreciated!

 

[Entwicklung34]

For a splash of perspective, from our real-world system.

Here in sunny Thailand 300W worth of panels will generate, on average, 1kWh per day. Some days much better, other days rather less good (OK total carp!).

Right now, we are getting about 40kWh per day from our 10kWP system, I expect that we will be down to 10kWh when the rain really sets in

I can certainly imagine 300w of panels being much more effective in Thailand thank the UK!! ?

 

[timselectric]

125% of the rated output of the SCC.

 

[Rednecktek]

Also, I looked through the booklet that came with the charge controller, I couldn't find anything related to standby power drain. I will do some online research for that.

Inverter. The charge controller is negligible and I wouldn't worry about it much.

It's a bit gutting because I've invested so much already to get going and now I'm looking at least at another £100 by the looks of it! Any thoughts on this one?

Yup, that's a good quality mid-range controller and will serve you well. You'll want a 30 * 1.2 = 36a fuse on that, which doesn't exist. You would do fine with either a 35a or a 40a as long as it's a DC rated fuse. AC fuses that you get at the hardware store don't work the same and will only give you a false sense of security.

It is quite disheartening when you pay "Tuition", which is what we call buying parts and finding out they don't work like we thought. Just look at my spare parts bin...

 

[Entwicklung34]

As RNT mentions, what you've got is a PMW controller, even if they said it was MPPT when you bought it. There are a lot of fake products out there. A PMW controller only controls the amps going into the battery, so any voltage above the 12.6V the battery wants is basically wasted.

PMW is OK for the smallest of systems, but I think the breakeven point is around 300W or so. Above 300W, you save money buying the more expensive MPPT controllers, because they allow you to use much cheaper/W grid-tie panels.

If you switched right now, I think you'd see about a 40% increase in amps going into the batteries. If you decide to get more panels, then definately get a better controller. BTW, MPPT will allow you to wire all your panels in series, which will also get another modest gain in power due to losses via voltage drop.

Brilliant thank you - one question I have here is that if I wire in series would that still be ok for my 12v batteries and the inverter? Does the mppt controller convert to correct voltage? (I'm very aware that could be a ridiculous question but my knowledge of watts amps volts is in the early stages!! ?)

Thanks!

Inverter. The charge controller is negligible and I wouldn't worry about it much.


Yup, that's a good quality mid-range controller and will serve you well. You'll want a 30 * 1.2 = 36a fuse on that, which doesn't exist. You would do fine with either a 35a or a 40a as long as it's a DC rated fuse. AC fuses that you get at the hardware store don't work the same and will only give you a false sense of security.

It is quite disheartening when you pay "Tuition", which is what we call buying parts and finding out they don't work like we thought. Just look at my spare parts bin...

Ah yes sorry I meant inverter! (Have a bit of brain fog at the moment due to some medical issues... I'm not normally this idiotic ?)

Haha tuition I love it... It's a nice way to think about it actually. I suppose I was trying to get a cheap system going but it's expanded now I can see it working so the basic stuff isnt going to hack it!

Thanks for the advice on the controller and fuse too - that is super useful. If you have any recommendations for a good inline 40amp DC fuse/breaker that would be amazing ?... I've seen a few options online but seeing some YouTube videos showing how they don't hold up to well so that has me nervous and I'm always mindful that I don't have one on there yet and it's pretty essential!

 

[Entwicklung34]

Some pics from just now... (19:00)

Battery is charging up from this morning but not rapidly by any means.

Excited to get checking the amps for each panel now - will do this as soon as I get a spare minute.

 

[Entwicklung34]

Actually, I see this myself early in the morning. My habit is to walk out to the utility room, coffee in hand, and watch the charge controller right at sunrise. Tuning in to the "electricity channel". My array's nominal voltage is ~118VDC, but right around sunrise, I see voltages as low as 98V. Once the batteries are fully charged though, I see the voltage bumping to to ~125VDC. So, that's a 27V spread from morning to afternoon.

Thanks Michael... So when I get my new mppt charge controller I can just wire in series with the same 12v leisure batteries is that right?

 

[camelCase]

Hair dryer + 210Ah lead acid batteries (105Ah usable) = flat batteries

 

[MichaelK]

Thanks Michael... So when I get my new mppt charge controller I can just wire in series with the same 12v leisure batteries is that right?

That's right. Keep in mind that when you wire panels in series, you need to pay close attention to the open-circuit voltage (Voc). That's the voltage you read with a voltmeter when the panel wires are disconnected from the load. More economical controllers have a Voc limit of 100V, whereas other controllers may have 200V, 300V, or even 600V limits. Of course you get what you pay for. As the Vmax goes up, so does the price.

Remember that the voltage of the panels goes up as the temperature goes down. At freezing, multiply the Voc by 1.12X. At -40F multiply by 1.25X. Your max voltage string voltage has to stay below the recorded lows for the weather in your region.

 

[crossy]

It is quite disheartening when you pay "Tuition", which is what we call buying parts and finding out they don't work like we thought. Just look at my spare parts bin...

Yeah, I have a parts-bin like that too.

Cheap SCCs, cheap 32650 cells, assorted modules that didn't quite perform as promised

 

[Entwicklung34]

Hair dryer + 210Ah lead acid batteries (105Ah usable) = flat batteries

I thought that might be the case! ?

 

[Entwicklung34]

07:30 Monday... (I've turned off the inverter until the battery reaches full capacity again!

 

[conquistador]

Your expectations are too high. The solar panels give in the best case 80% of their rated output.
The issue with your system is the constantly running inverter. My 1000W AIO inverter draws 20W idle. That means 0.5kWh per day for nothing.
So put the lights to 12V, and turn the inverter on only when needed.

 

[Rednecktek]

07:30 Monday... (I've turned off the inverter until the battery reaches full capacity again!

That 2a is still less than half of what a single panel should be producing. What's the weather outside look like?

 

[StuartV]

07:30 Monday... (I've turned off the inverter until the battery reaches full capacity again!

I turn my inverter off every night, to stop battery drain.

I have an Iconica all in one, so when the sun/light hits the panels in the morning, it starts charging the battery without it being on, so no drain from the inverter.

I've had mine set up for nearly 4 weeks now, only ran out of electricity once and had 4-5 non-solar electricity days so far ?

UK weather hey! ??