Current monitor for mini-solar panels (18V, ~20W)

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SteanX
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by SteanX »

[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Sun Sep 01, 2024 2:53 pm It is still hard to understand if is really a valid economic solution to install solar panels considering the cost vs the efficiency.
This question changes completely when your country's power provider runs out of steam (excuse the pun) and you start having blackouts every day :-) Where I live, we had 289 days of the 2023 year with some form of power outage, normally 2 hours a day, but sometimes repeated more than once. Worst case you would have 4 x 2 hour outages a day and if you were unlucky, when power returned there was an overload and some infrastructure got damaged. In such cases you could be off for whole the rest of the day and maybe the next few days too! While you can get away with an inverter and some batteries for the short outages, solar just becomes essential when you don't know when (or even if) power will return.

But yes, where best to put them and how to orientate the panels? You can of course just get the panels, move them around and measure them. But that becomes a lot of effort when you have a few of them that weigh in at around 23kg each, especially on a roof! Or you can use small little panels and measure like in this awesome post. As an alternative, you can also use a light intensity sensor and use that to compute what you might experience with real panels. I did this back in 2019 with a MAX440099 I2C light intensity sensor connected to an 8266-based D1 Mini. It's super easy to connect with Annex, and you can easily move it around your yard and leave it for a while to find the best place/orientation.

Here is an example of the sort of measurements it gave for a given location:

Image

I've got a little writeup on it with the simple Annex code here if anyone is interested?
Last edited by SteanX on Tue Sep 03, 2024 4:30 pm, edited 1 time in total.
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PeterN
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by PeterN »

Thanks BeanieBots,
An Impressive installation1

I particularly agree with you about the temperature dependency.
I have mounted my panels a few centimetres away from the screens in order to have better air cooling. But I also see a strong influence of the panel temperature.
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by cicciocb »

[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Tue Sep 03, 2024 4:12 pm
[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Sun Sep 01, 2024 2:53 pm It is still hard to understand if is really a valid economic solution to install solar panels considering the cost vs the efficiency.
This question changes completely when your country's power provider runs out of steam (excuse the pun) and you start having blackouts every day :-) Where I live, we had 289 days of the 2023 year with some form of power outage, normally 2 hours a day, but sometimes repeated more than once. Worst case you would have 4 x 2 hour outages a day and if you were unlucky, when power returned there was an overload and some infrastructure got damaged. In such cases you could be off for whole the rest of the day and maybe the next few days too! While you can get away with an inverter and some batteries for the short outages, solar just becomes essential when you don't know when (or even if) power will return.

But yes, where best to put them and how to orientate the panels? You can of course just get the panels, move them around and measure them. But that becomes a lot of effort when you have a few of them that weigh in at around 23kg each, especially on a roof! Or you can use small little panels and measure like in this awesome post. As an alternative, you can also use a light intensity sensor and use that to compute what you might experience with real panels. I did this back in 2019 with a MAX440099 I2C light intensity sensor connected to an 8266-based D1 Mini. It's super easy to connect with Annex, and you can easily move it around your yard and leave it for a while to find the best place/orientation.

Here is an example of the sort of measurements it gave for a given location:

Image

I've got a little writeup on it with the simple Annex code here if anyone is interested?
Yes, I live in a country where this problem do not exists.
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by BeanieBots »

[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Tue Sep 03, 2024 4:12 pm ...a lot of effort when you have a few of them that weigh in at around 23kg each, especially on a roof! ...
I had to laugh because it reminded of when I replaced one of the panels.
Back then, I was a lot more fit than I am today and decided that all I needed was a large step-ladder.
Fine, right up to the point when I went to put my foot back on the ladder (whilst still holding the panel) and managed to kick it over!!!!
So, there I was, one foot on the roof, one foot dangling in the air and holding on to a loose panel that I could barely lift with my elbow in the gutter being the only thing stopping from plunging to the ground to be follwed by the panel.
My wife came out when she heard the ladder fall and asked "are you all right?".
I replied with "does it look like it?" and politely asked if she could pick up the ladder.
Moral:- when working with ladders, always tie them to the wall and NEVER work alone. That could easily have been fatal!

One other quick thing to note. My inverter is grid tied. The irony of that is that when there is a power failure, I lose the solar too :roll:
I do have some other small 12W panels on the workshop roof which maintain a 100Ahr Pb battery just for emegencies which are rare now.
Not like the seventies when Maggi and the miners fell out and we had scheduled power outages every other day because there was no coal for the power stations. Happy days ;)
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by lyizb »

[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Tue Sep 03, 2024 4:12 pmhow to orientate the panels?
Great little device, and thanks for linking to the code.

Power where I am in Nova Scotia is pretty reliable (2 kilometers from the electrical substation and 4 kilometers from a hospital on the same net which they like to get back up on mains as quickly as possible when the grid goes out), but last year hurricanes gave us two outages of about 10 hours each. It would have been nice to have had a backup source--especially one which stepped in automatically.
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by lyizb »

[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Tue Sep 03, 2024 5:13 pmMoral:- when working with ladders, always tie them to the wall and NEVER work alone.
People sometimes ask why I have big eye-bolts screwed through the fascia board into the rafter ends on the front of my house, and at places on the barn. That's so a ladder can be strapped to them. I myself can't do ladders, but when I've had people up painting dormers, I have them strap their ladders to the eye-bolts.

Glad you made it through that experience OK.
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by lyizb »

[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Tue Sep 03, 2024 1:21 pmI live on the fourth floor at 52 degrees latitude and only have a south-west facing balcony
Very interesting. I wonder what the reason is for the 800W limit?

I had seen mention of the balcony-mounted solar arrangement, but had no idea how it actually worked. Thanks for sharing.
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by PeterN »

Hi lyizb,
just had a look at the map to see Nova Scotia in Canada. I guess you have a greater distance to your nearest neighbour than I'm used to here in the west of Germany :-)

Perplexity helped me a bit to find the proper reason for the 800W limit:
https://www.perplexity.ai/search/why-is ... m5k7qpZflQ

In the last two years, I have had the honour of helping to install 5 solarpower systems on the balconies, garages or rooftops of some friends. Fortunately, it was less dangerous than with BeanieBots :-) My friends are all equipped with much more and safer mounting space than I have. So I was forced to be a little more careful and cautious with my installation. Local building regulations also require very reliable mounting methods for heavy panels at great heights. This led me to the lightweight flexi panels.

But all my friends and I are now very happy with the modules and the grid-connected inverters. Fortunately, the last power cut was ... oh ... I can't remember ;-)
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by lyizb »

[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Tue Sep 03, 2024 6:31 pm a look at the map to see Nova Scotia in Canada. I guess you have a greater distance to your nearest neighbour than I'm used to here in the west of Germany
My nearest neighbor's house is less than 4 meters from mine, and I have grocery store, hardware store, lumber yard, and dollar store within 4 kilometers, but someone could walk out my across-the-street neighbor's back yard, head west northwest, and walk about 100 kilometers before hitting a paved road. But Nova Scotia is long north-to-south; my house is just a little more northerly than Florence, Italy.
[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Tue Sep 03, 2024 6:31 pmPerplexity helped me a bit to find the proper reason for the 800W limit:
Thanks for that. Perplexity.ai is my favorite site to ask questions like that. I have gotten some totally wrong answers, but upon prodding it has admitted it was wrong and gotten to the right answer.
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Re: Current monitor for mini-solar panels (18V, ~20W)

Post by PeterN »

Thank you for explaining your living environment, lyizb
[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Tue Sep 03, 2024 8:28 pm Perplexity.ai is my favorite site to ask questions like that. I have gotten some totally wrong answers, but upon prodding it has admitted it was wrong and gotten to the right answer.
I like that perplexity.ai accesses actual internet content and provides the link list so that you have the opportunity to critique the responses.
I have also had other positive and negative experiences with ChatGPT: https://peterneufeld.wordpress.com/2023 ... evitation/
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