diy solar

diy solar

System check.

Capacity 100%, your batteries are full and it's only pumping through a trickle of power to keep everything topped up and the 220ish watts you're using at the moment.

Actually looks pretty good!
 
Rednecktek said:
Capacity 100%, your batteries are full and it's only pumping through a trickle of power to keep everything topped up and the 220ish watts you're using at the moment.

Actually looks pretty good!
Click to expand...
Okay.

Instead of making a fool of myself, I should probably Google this - but - if I remember correctly (I did my electrical and electronic diploma decades ago and don't use it), watts and amps can only be measured under load, because it depends on usage?

Volts stays as it is - but if my batteries were flat and the charge controller was charging them at max capacity - I'd be seeing a far higher wattage coming from the panels.

Again, I'm cringing asking these questions - I should know this stuff...

In the second image - in the Battery section, it's reporting a current of 15.61A. What is that a measure of? All I have connected to the battery is an inverter, which is drawing - hold on I'll check... 40w. There is no 12v load on the charge controller.

Cheers

Paul.
 
(I should read replies properly - MichaelK has already answered my question around current/watts measurements...)
 
pa_broon said:
Volts stays as it is - but if my batteries were flat and the charge controller was charging them at max capacity - I'd be seeing a far higher wattage coming from the panels.
Click to expand...
Exactly. Since your batteries are full there's not as much wattage being pushed through the SCC to the batteries.

pa_broon said:
In the second image - in the Battery section, it's reporting a current of 15.61A. What is that a measure of? All I have connected to the battery is an inverter, which is drawing - hold on I'll check... 40w. There is no 12v load on the charge controller.
Click to expand...
Don't you have the computer and monitors plugged into the inverter? Those should account for the rest of the amps. Either that or it's really at 99%-ish and topping the batteries off at the time of reading. 40w is about 4a on a 12v system, so another 10-ish amps of load, or 120-ish watts plugged into the inverter? Remember that laptops and monitors and other electronics usually have a standby load of their own. You mentioned that when you were only getting 115w out of the panels earlier it wasn't keeping up with the laptops and such.

Now, having said all that, if your laptops and monitors and lights are all unplugged and it's still feeding 15a then there's something wrong or it's doing an equalization charge cycle, which is normal for lead acid batteries.
 
pa_broon said:
I also don't understand the current output of the panels being 2.41A but the current going into(?) the battery being 15.61A. What is that latter value - what is it actually measuring?
Click to expand...
W = A x V

The incoming V x A = W. 93.64V x 2.41A = 225.93W. That's what you see under the PV Component section. The MPPT controller then converts those incoming watts in the battery charge voltage and battery charge current. 225.93W / 14.68V = 15.39A. Though your display shows 15.61A. I'm not sure where the extra 0.22A are coming from but that is the basic idea. The numbers have nothing to do with loads. It's simply a conversion of the incoming watts from the panel into the charging watts to the battery. Because those two are based on different voltages you get different currents. But it's still the same amount of watts.
 
Okay.

Between both your posts, I get it. What the inverter is telling me - has nothing to do with any numbers coming from the charge controller module. And what the charge controller (via the bluetooth module), is telling me has nothing to do with my actual usage. It's all about input.

Further more (and crucially, because this confused me). The battery capacity refers to the battery's charge condition according to the charge controller - and has nothing to do with usage or available percentage, (because available percentage - or charge - will depend on what I have plugged in.)

The charge controller doesn't monitor the battery's output. I'd need a battery monitor of some kind to do that.

That sound accurate?
 
Rednecktek said:
You got it! If you're wanting to keep track of all the loads in and out you need some sort of shunt monitor in the system to track the power going in and out of the battery bank.
Click to expand...
Great stuff.

Thanks.

(Give me a few days, and I'll be back with more silly questions... :cool: )
 
Me Again.

A question about charging and how the charge controller works - and I suppose by extension, me not being clear on what my panels are doing.

Current stats -

PV Component - Voltage, 89.29V - Current, 1.21A - Power, 110.12W

Battery - Voltage, 12.60v - Current 8.71A - Capacity 55%

I'm drawing about 80w according to the inverter. It's not massively sunny, but there are shadows (I have three 12v 130Ah batteries in parallel...)

My questions are -

I have 6 x 205W panels, why is the controller only drawing ~110W from them - could it not draw more (given the panels are in direct sunlight) to get the battery up to full capacity more quickly?

I 'work' (ha ha) during the day here - using those 80w (sometimes more) - and come evening, the battery capacity never gets to 100%, so when I'm sitting watching the latest thing on Netflix, I worry I'm going to run out of power - why are my panels not being fully utilised during the day?

I have 6 more panels which I've going to add to the existing array, (6 x 195w mono panels - 2 x 3 in series connected in parallel. Voltage stays the same/current doubles. All within the parameters of my current CC.) If my controller is only taking 110w when it 'knows' the battery capacity is low, why am I doubling my panel capacity?

Those are my queries.

By way of a heads-up, tomorrow I'm picking up 7 x 120W panels which I hope to use to heat water - a solar dump? I see on YouTube etc the Cybo H solar inverter. These aren't available in the UK, so I'll be looking for info on how I might tie these panels - via an inverter/controller - directly to my hot water tank. (I believe, the element will still heat, at a much reduced capacity all day - assuming the sun is out - the idea being it keeps it topped up. This will be off-grid.)

But that's for another post.

This solar stuff is addictive, although being able to escape from under the cosh of the utility companies is excellent motivation... ;-)

PS: in the time it's taken me to type all this, PV power has risen to around 260W - but it's not more sunny. I assume that's the MPPT thing doing it's job? The battery is now charging at a higher rate. (I've also just turned a small laser printer on, so it'll be heating - but the controller won't know that. (I'm blethering now...)
 
pa_broon said:
It's not massively sunny, but there are shadows
Click to expand...
This is likely the issue. How are your panels connected? All in series or ?.

Any shading on a series string, even a single panel can drag down the entire string.

The shadows are pretty long in your photo so you will not reach panel spec watts without sun high overhead.
 
MisterSandals said:
This is likely the issue. How are your panels connected? All in series or ?.

Any shading on a series string, even a single panel can drag down the entire string.

The shadows are pretty long in your photo so you will not reach panel spec watts without sun high overhead.
Click to expand...

I probably should have been more clear, (or less shadowed, haha ummm...)

Anyway, when I said shadows, I didn't mean the panels were in shadow, I meant there were moderate shadows - meaning there was discernible sunlight.

I have six panels, three connect in series and those two sets of three, connected in parallel.

You were right about the long shadows, as the day has progressed, the panel output did increased.

I think I might be overthinking things - my batteries are at full capacity now. More over - where before, the low voltage alarm had been going off in the evening on dull days - I've since added a third battery, and that's not happened since. (I also unplugged my fridge from the solar supply - that's back on mains now.)

My plan is, to increase the panels and increase the battery capacity so I can get more of the house off-grid.

I'd also like to explore the solar dump (hot water idea). I have more panels coming, so I can use those specifically for the purpose of heating water - if I can figure out how best to do it.

The plan is to go fully off-grid - so when my energy supplier threatens to cut me off, I can tell them to go ahead. :)
 
pa_broon said:
I have 6 more panels which I've going to add to the existing array, (6 x 195w mono panels - 2 x 3 in series connected in parallel. Voltage triples/current doubles
Click to expand...
Fixed that. 3 in series means the voltage triples.
 
WYtreasure said:
DC water heater elements might be a good "dump" with no inverter load.

Hey Pa, what is your latitude?
Click to expand...
That is what I have but I have my DC elements connected directly to a set of panels. Because I use most of my energy, I did not have anything to dump.
 
GLC said:
That is what I have but I have my DC elements connected directly to a set of panels. Because I use most of my energy, I did not have anything to dump.
Click to expand...
I like simple. It's hard for me to screw it up.
Details please, lots of em. ?
 
WYtreasure said:
I like simple. It's hard for me to screw it up.
Details please, lots of em. ?
Click to expand...
You will get different responses on what I did but it works for me. I purchased a 36 volt dual probe 1200 watt DC water heating element. I took the lower AC water heater element out of my water heater and inserted the DC element. Previously I tried several different wattage/voltage of water heater elements and the one I listed is the one that worked the best. I also tried from one to 4 panels and found what worked the best. I wired up 3 panels, 305 watt , VOC 45.6 volts, ISC 8.921 amps wired parallel. I put 3 panels on the south west side of my roof to get afternoon sun and wired them to one side of the dual probe heating element. I also installed 3 panels on the south east side of my roof to get morning sun and wired them to the other side of the dual probe thermostat. I get sun throughout the day heating my water. I left the upper ac water heater element in the water heater but turned down the thermostat to around 120 degrees just for days that I do not get a lot of solar gain. Also, I have always had a timer/clock on the water heater so the ac element would only come of at 5 am to 7am and then again at 4 pm to 9 pm. I do not have a thermostat on the DC elements. You will get different views on this also. I am attaching the dc element and the original thread of how I accomplished this.
Since I first did this I have added a shunt monitor that monitors the amount of solar gain that I have going to the element at any given time.
diysolarforum.com

DC water heater element?

Has anyone tried these? Just wondering if they actually work. I was wondering what to do with extra energy from the panels I have.
diysolarforum.com diysolarforum.com
 
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