System check.

pa_broon said:

55.9533° N, 3.1883° W

I'm just about to clambour onto the roof with these panels. If you hear a thud, that'll be me landing.

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This is Spring, not Fall.?

Just some images of the first set up there. (That fourth battery isn't connected, I'm waiting for cables.)

I know this is difficult to judge from pictures. But looking at the last one there, (the screen shot of what the SC is doing), I'm suspicious of how I have this set up, and my expectations of it all.

Looking at the battery capacity (25%), the voltage (11.75v) - it's low. Sure, I had stuff switched on which dragged it down - but, what I can't understand is - why the controller isn't pulling more watts off my panels?

I have 6 x 205w panels, and fair enough, they've only been in sunlight for a couple of hours - but I'm just not sure this is all set up correctly (or that I've got the right set-up?) Although the battery pack is low (either from the controllers pov, or actual usage), even under ideal circumstances (full blazing sunshine, well, as much as that's possible in Scotland), I've never seen the controller pull more than 300w from the PV array.

First Questions -
What's the point in me having 6 x 205w if that capacity is never fully used? (If it's slightly dull, patchy cloud, between my six panels, are they only managing to generate about 8-9w each to give that paltry 48w, or is the charge controller - knowing the batteries are low - only asking for 48w?)

Second question -
Is this an issue with the rate at which the batteries can be charged? If so, do I need different batteries, or do I need to dive in and get some sort of grid-tied hybrid controller inverter so I can fully utilize the panels I have? (I have another 6 x 195w panels to go somewhere...)

(I like mechanical things where I can see what's happening. If it's not working, you can see what fell off, snapped in half, or caught fire... ;-) )

I also now have a second array at the back of the house - 6 x 120w panels connected to a (terrible) 'Perfect Suitor' charge controller (seriously, it's rubbish - it's making a disturbing clicking noise as I type this. I tapped it and it stopped...) That in turn is connected to two 130Ah lead acid leisure batteries (connected in series), which in turn are connected to an Edecoa 300w MSW 24v inverter which I got quite cheap.

The idea with this second array is to power stuff in the kitchen - which for me is a fridge, a kettle, and probably an air fryer. (Not all at the same time though.) I know I'll need to improve battery storage on this system. And, the panels are south east facing, so will get the brunt of their sun pre-midday.

pa_broon said:

I know this is difficult to judge from pictures. But looking at the last one there, (the screen shot of what the SC is doing), I'm suspicious of how I have this set up, and my expectations of it all.

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I noticed the time in your last picture. 10:22 where you are is still about 3 hours from Solar Noon. Can you confirm that Solar Noon is 1:14pm?
Considering the 38.33 degree sun angle you will have at culmination (solar noon), I would not expect much production from your panels at the time of your screenshot.

pa_broon said:

Looking at the battery capacity (25%), the voltage (11.75v) - it's low. Sure, I had stuff switched on which dragged it down - but, what I can't understand is - why the controller isn't pulling more watts off my panels?

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I don't think it had any Amps to give.

pa_broon said:

I have 6 x 205w panels, and fair enough, they've only been in sunlight for a couple of hours - but I'm just not sure this is all set up correctly (or that I've got the right set-up?) Although the battery pack is low (either from the controllers pov, or actual usage), even under ideal circumstances (full blazing sunshine, well, as much as that's possible in Scotland), I've never seen the controller pull more than 300w from the PV array.

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The controller can't pull what's not there. Your sail has no wind.

pa_broon said:

First Questions -
What's the point in me having 6 x 205w if that capacity is never fully used? (If it's slightly dull, patchy cloud, between my six panels, are they only managing to generate about 8-9w each to give that paltry 48w, or is the charge controller - knowing the batteries are low - only asking for 48w?)

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The point of having a bunch of panels is to capture as much energy as you can. The only "moment" your panels will produce 100% rated power is when the sun is directly above and the panel is pointed directly at the sun. Most folks agree that very few ever achieve 100% of the rated power production.

pa_broon said:

Second question -
Is this an issue with the rate at which the batteries can be charged? If so, do I need different batteries, or do I need to dive in and get some sort of grid-tied hybrid controller inverter so I can fully utilize the panels I have? (I have another 6 x 195w panels to go somewhere...)

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I don't think the batteries are the cause, unless there is no liquid in them.
Could there be poor connections between the panels and the controller? That's a relatively easy check, as long as you don't shock yourself. Have you inspected the connections in the junction boxes on the back of the panels?
That's about the best I can offer and I could be wrong.

Thanks for your reply.

I understand the panels won't produce anything like what they say they will, and I understand the controller will only use what it needs. I need to do some reading on what the MPPT function is all about.

You're right too, the screenshot was early in the day - the sun was not at it's highest. Later on the batteries got to 100% very quickly, and I saw the controller pull 500w plus from the panels at one point.

I rewired all my batteries this afternoon - to double check connections and to tidy up. I think that's my system's weakness just now - not enough storage.

I still have a concern, that when I'm working during the day, I'm using power, (about 3-400w). Come 5pm-ish, when I finish, even although it's been sunny, the controller hasn't topped the batteries up - they're never at 100% come teatime and because the sun is moving round, it's too late for the system to catch up. (I'm going to add another three panels facing west to catch the early evening sun.)

The thing is, will the controller use that last wee surge and charge the batteries? (This is why I need to do some reading on the MPPT function.)

Also, as a footnote, those horrible 'Perfect Suitor' controllers... Quick note, they'll do a 24v system, even auto-recognises the batteries. But. The load output also goes to 24v. I melted some LED assuming it would be at 12v.

Oh well. At least I was in when they caught fire... (I'm joking, it was just a wee bit of smoke... ;-)

pa_broon said:

Thanks for your reply.

I understand the panels won't produce anything like what they say they will, and I understand the controller will only use what it needs. I need to do some reading on what the MPPT function is all about.

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After you figure that out, share with me so I know. I still think of that magic box as "Smoke and Mirrors" technology.

pa_broon said:

You're right too, the screenshot was early in the day - the sun was not at it's highest. Later on the batteries got to 100% very quickly, and I saw the controller pull 500w plus from the panels at one point.

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Yea, I sometimes run up and down the street screaming "the sky is falling the sky is falling". Luckily Boss Lady reminds me it's just rain.

pa_broon said:

I rewired all my batteries this afternoon - to double check connections and to tidy up. I think that's my system's weakness just now - not enough storage.

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Are you using any compound on your terminals and connections? Are you testing the resistance of your wires, tip to tip?
I know how to do that, I don't know how to test for load carrying capacity. I'm tinkering with a 35 year old Chevy and have come to the conclusion it needs new battery terminal post clamps. I think the little tiny bit of NOT CRAPPED UP connection is showing me lots of volts, but the starter can't get the Amps it needs through the little tiny bit of good connection that still remains.
Which terminal post connections are you using? They look pretty, hopefully they carry the Amps without getting too warm.

Cool thread on connections and how to put them together properly to prevent corrosion.

pa_broon said:

I still have a concern, that when I'm working during the day, I'm using power, (about 3-400w). Come 5pm-ish, when I finish, even although it's been sunny, the controller hasn't topped the batteries up - they're never at 100% come teatime and because the sun is moving round, it's too late for the system to catch up. (I'm going to add another three panels facing west to catch the early evening sun.)

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With what I know now, I just think "the bigger the sail, the more wind you catch". So yep, more panels will help.
Do you shut down all your drains and your inverter at the end of the day?

pa_broon said:

The thing is, will the controller use that last wee surge and charge the batteries? (This is why I need to do some reading on the MPPT function.)

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I think it will help.

pa_broon said:

Also, as a footnote, those horrible 'Perfect Suitor' controllers... Quick note, they'll do a 24v system, even auto-recognises the batteries. But. The load output also goes to 24v. I melted some LED assuming it would be at 12v.

Oh well. At least I was in when they caught fire... (I'm joking, it was just a wee bit of smoke... ;-)

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Apparently that perfect suitor isn't your perfect suitor. If it keeps ticking, disconnect everything and use a bigger hammer.

Lots to think about there.

I'm not too concerned about the quality of connections - the batteries are indoors so there won't be any damp. (Ventilation has been mention, but my house is so drafty, it really isn't a concern.)

It's quite cold here just now, we're having a final cold snap before spring arrives - which is just in time for the energy price hike which kicked in25 minutes ago. Our energy price (per unit) has increased by up to 80%.

With summer approaching, I won't need heaters quite so much. But come October - when another price hike is expected - I'll need to have something in place. I hope to expand the solar capacity I have, but I need to get the balance right in terms of how I have it set up. I wonder if it's worth investing in solar inverters (in series). The batteries... I know I should go for Lithium, but they're so pricey. I have room for more lead acid batteries... Lots to think about, and spend money on...

I detest my electricity supplier, so it's worth it.

PS: I had a Chevy Blazer (UK car), it was a total wreck - nothing worked on it... But, it had the same problem - no power, it was as if the battery wasn't connected. But it was and it was new. Turned out it was the connector, it was on there - we could see it. Then we noticed it had obviously been a problem for the previous owner - they'd driven a self-tapping screw down between the connector and battery post to close the connection. When they sold the car, they removed it. The car was fine for a bit, but eventually the connection went again. The only reason we spotted it was because we could see where the screw had been and my pal (a mechanic) has seen it before on other cars.

Hi Folks.

Just me again.

I have a question about fuses. I have a fuse between my 50A ePever SCC and my batteries - it's a 60A fuse. I did have a 50A fuse in there, but it kept popping. Now the 60A fuse is popping. It's a 50A SCC, when it pops it is at the upper level of what it can output - around 47A.

I think the fuses are just rubbish (from Amazon.) But why am I putting a fuse between the charge controller and my battery bank anyway? It's never going to punt out more the 50A, the cable is 16mm2 (6AWG) so good for 110A. (They do get warm, but never too warm to touch.)

Since the ones I have keep popping, why do I even have it there?

As a side note, there doesn't seem to be any reason for it, just happens randomly - I will say, just now, it just keeps popping, I reset it and it pops again. It's not too cold, not too warm, it's not wet or damp, there are no ghosts I am aware of in residence here... I don't have mice...

This will be the second dodgy fuse I've fitted (same make/different value as the last one).

Thanks

Paul B

pa_broon said:

fuses are just rubbish (from Amazon.)

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Link?
Fuses and wiring are meant to be about 25% over expected amps to prevent nuisance blows.

I'm just reading some of the reviews, many are saying they blow way to early. I think I need to get rid of it and replace.
My question still stands though, if the charge controller can only put out 50A, (I appreciate it may malfunction), and the cable you're using is good for 110A - do you really need a fuse?

*edit* I've put the old 50A fuse back in and it's fine.

That is an audio breaker and is essentially junk.
Some folks do not fuse from SCC to battery. I usually do not as there are other protections like the BMS for over current.

pa_broon said:

https://www.amazon.co.uk/RKURCK-12V-24V-Circuit-Inverter-Protection/dp/B074RKG5KT

I'm just reading some of the reviews, many are saying they blow way to early. I think I need to get rid of it and replace.
My question still stands though, if the charge controller can only put out 50A, (I appreciate it may malfunction), and the cable you're using is good for 110A - do you really need a fuse?

*edit* I've put the old 50A fuse back in and it's fine.

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Yep , those are pretty well junk. I started out with those. Currently I am using these from Bussman but every so often these fail too.

I've ordered a longer length of cable, I'll just do away with a fuse - I just don't see the point.
It was fine for the rest of the day with the 50A fuse refitted.

By cheap, buy twice - as they say.

Just me, (again).

I've Googled, and I think I know the answer, (what that means is, I don't know the answer...)

I have two arrays set up. The one in the kitchen is smaller, I got a deal on a 24v inverter so go two 130Ah batteries and wired them in series. Fair enough.

I know if you put batteries in parallel, the voltage stays the same and the capacity is increased per battery.

So I have 4 x 130Ah batteries in parallel for the front array here, my voltage is 12v, and my capacity is 4 x 130Ah (Nominal. I know it isn't actually as much as that).

In the kitchen, I have two batteries in series. I know my voltage is 24v, (I definitely know this because I melted some 12v lighting with it...)

But what's my capacity? 2 x 130Ah batteries = ??? Ah

I run a lot less on the back array, just a fridge and an 1kw air fryer for maybe 10 or 20 mins (I have 6 x 195w panels, 3 x 2 in parallel). I don't leave the back array on overnight, because the voltage drops and it starts beeping in the middle of the night. Is it worth moving it to a parallel set up?

pa_broon said:

In the kitchen, I have two batteries in series. I know my voltage is 24v, (I definitely know this because I melted some 12v lighting with it...)

But what's my capacity? 2 x 130Ah batteries = ??? Ah

I run a lot less on the back array, just a fridge and an 1kw air fryer for maybe 10 or 20 mins (I have 6 x 195w panels, 3 x 2 in parallel). I don't leave the back array on overnight, because the voltage drops and it starts beeping in the middle of the night. Is it worth moving it to a parallel set up?

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In series voltages add while amperage stays the same, so you have 130Ah X 24V = 3120Wh of power. Utilizing half that, your useable capacity is 1.5kWh of power. That is not much, especially running a refrigerator. Your problem is that your battery is too small for this system. What inverter do you have, and what is it's background consumption?

Let's say your inverter has a background consumption of 75W just being left on? Someone else mentioned 75W the other day for their inverter, so let's use that? 75W X 24hr = 1800Wh of power. Also assuming you have a frig that consumes ~1200Wh of power per day (that's mine) that works out to be 1800Wh + 1200Wh = 3000wh, or basically every watt your batteries have.

Looking at your solar, you have 195W X 6 panels = 1170W, and assuming they charge your batteries at 25V and you get 85% output, that works out to be (1170W/25V) X 85% = 39.8A. Call it 40A. Assuming you want to charge at 1/8th of C, then you could be charging a 40A X 8 = 320Ah battery.

When you say "Is it worth moving it to a parallel set up", do you mean splitting the 24V bank into two 12V batteries in parallel, or do you mean buying more batteries to put in parallel with the first 24V string? No, going back to 12V is not going to improve things, and most likely will make things worse. At least doubling battery capacity at 24V is the correct way to go, and more likely expanding the battery bank to six batteries for 2S3P might be the best way to utilized that 40A of charging current. So, get at least 2, but better 4 more of the same batteries and wire them into parallel strings at 24V. This will give you enough battery capacity to get through the night, but still get fully charged by the end of the day.

Thanks for the info.

I'd done the sums, roughly anyway. The set-up in question isn't overly optimised, non-MPPT charge controller, lower quality panels, not in a prime location... I have more batteries on the other array at the front of the house - they're fine in the summer, but do struggle a bit in the winter - as one might expect.

My question really was about the Ah's, will two batteries in series have their capacity added together in the same way as two batteries in parallel? I'm assuming they do but wanted to rule it out.

I'll upgrade both systems for the coming winter. It's on my to do list.

Thanks.

pa_broon said:

My question really was about the Ah's, will two batteries in series have their capacity added together in the same way as two batteries in parallel? I'm assuming they do but wanted to rule it out.

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Dude, the answer to your question is the very first sentence of the last post!

In series voltages add while amperage stays the same, so you have 130Ah X 24V = 3120Wh of power.

Amphour capacity is NOT doubled in series. Voltage is doubled in series.

That wasn't clear to me - I didn't understand the relationship between volts and Ah's and volts and Wh's.

Just looking for clarification... Dude...