Author Topic: Where do I start with solar?  (Read 1187 times)

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Online paulca

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Re: Where do I start with solar?
« Reply #25 on: January 10, 2018, 05:49:36 AM »
Charge controller and battery arrived.  Battery arrived with 12.38V so it's not broken.  I don't have a load capable of capacity testing it properly, but I'm not that fussed as long as it does the job.

Wired it up, partially anyway, and the charge controller powers up and while it says it's daylight due to indoor lighting, it obviously isn't getting enough to put anything into the battery.

I'm not going to run it until the weekend when I'm present and it might take me a bit of time to trust it to run while I'm out at work.

I have a metal cased fridge I don't use.  I'm tempted to put the charge controller and battery inside it as some minimal fire protection.  How worried should I be?
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Offline metrologist

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Re: Where do I start with solar?
« Reply #26 on: January 10, 2018, 06:05:34 AM »
I have not taken any precautions with my batteries. One is for motorcycle and the other for a typical family car. Since they are wet cells, I would not put them in the house, but on the bench in the garage seems fine. The e-bike Li-ION batteries get moved around as shrink-wrapped battery packs would.

I would not even worry about SLA - most backup power supplies use them, so just don't short it out.

I used some automotive aux lights to test my system - something that would drain more than the system could output. I should run that all day to see what the system could actually cope with.
 

Online paulca

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Re: Where do I start with solar?
« Reply #27 on: January 10, 2018, 08:05:08 AM »
I have got a 5A DC load I built, but it would take nearly 5 hours to drain the SLA (26Ah).  I also have some 100W power resistors, but they are 1Ohm and 0.1Ohm, so that's what on 12V...  The 1 Ohm would draw 12 amps / 144 watts.  I might have two of them, in series they might make it, 6Amps, 72 watts shared between them.  Still going to take 5 hours and not something I would leave unattended.  The 0.1Ohm would make fire.

Anyway, I wired a load up to it and it's charged it's first LIon pack (via a Turnigy charger mind).

So... do I put the panel in the window and risk leaving it when I go to work?  I'm thinking, no.  I can't confirm the MPPT portion does not have a fault that will let smoke out while I'm at work.  I don't want to come home to a broken in door and bill from the fire service (as it will set off the building wide fire alarm) ... or much worse.

Saturday then.  Which will give me time to discharge the SLA a bit and give the panel something to do Saturday morning.
« Last Edit: January 10, 2018, 08:07:13 AM by paulca »
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Offline mtdoc

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Re: Where do I start with solar?
« Reply #28 on: January 11, 2018, 03:35:10 PM »

I have a metal cased fridge I don't use.  I'm tempted to put the charge controller and battery inside it as some minimal fire protection.  How worried should I be?

With a SLA battery you have nothing to worry about. No need for metal enclosure. Even with FLA batteries - you only have to worry about significant amounts of hydrogen gas venting during equalization and then it's only an issue if you have a large battery bank (> kWh worth).  Large FLA battery banks require enclosures with venting to outside.

Since they are wet cells, I would not put them in the house, but on the bench in the garage seems fine.

In the house shouldn't be an issue unless you plan on spilling electrolyte on your carpet...    Of course as above, a large FLA battery bank needs an enclosure and venting to the outdoors.
 

Online paulca

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Re: Where do I start with solar?
« Reply #29 on: January 14, 2018, 08:32:58 PM »
I have solar power!  Woohoo!

Put the panel in the window yesterday, but it was the darkest, wettest, miserable of days.  The CC did register charging, but 0.0A.

This morning however it's blue skies (for now) and the sun isn't up above the houses across the street and I have registered my first amps to battery, 0.1A.

Will see how far that gets when the sun is up properly before the weather closes in later again.

EDIT:  And when the sun came out from the behind the houses I have 1.1Amps.  Oddly the charge controller has not switched to PPT mode, it's sitting at 14V, the max power point of the panel is 17V.  I read this about the Tracer, at low power levels it remains in PWM mode and just sustains a charge voltage for the battery.  Maybe if the sun comes up out of the horizon haze it will improve.

I'm not expecting the full panel 50W behind a window, but 25W would be nice to see in direct sun light.  Any more would be a bonus.
« Last Edit: January 14, 2018, 09:10:55 PM by paulca »
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Online paulca

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Re: Where do I start with solar?
« Reply #30 on: January 18, 2018, 08:28:41 AM »
Our weather sucks.  There has been virtually no sun this week.  I started with a battery voltage of 12.2V and I now have a voltage of 12.6V.  I've taken no load off it.  I have also taken to switching the battery off at night and back on in the morning to save the little the charge controller is pulling.

I did manage to get it all fused and switched up properly.  Makes me feel a bit safer leaving it unattended.

I bought an RS485 to USB adapter and played with it's software, but I want to log the data.  So in the post is a MAX485 board and another ESP8266.  It can send it's data to my existing data logging set up (originally for home heating but now generic enough that it will accept any data over the network).  It will create RRA archives and graphs for the panel volts/amp/power and battery/volts/amps.

I also plan to sleep the ESP overnight, once the panel voltage drops below 5V or so it can deep sleep and wake up periodically to check for dawn.  It will be running of the charge controllers RS485 5V.

Interestingly(?) I was going to add a "light level" sensor to my data logging system, but monitoring panel power seems a lot easier than messing about with calibrating LDRs.
« Last Edit: January 18, 2018, 08:30:51 AM by paulca »
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