smurphy
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Post by smurphy on Mar 8, 2020 2:06:46 GMT -8
Hi all,
just realised that the lone solar array won't suffice to power my Weather Station on cloudy days. I barely get 0.5W out of it, while my installation requires 0.7W just to run. So not even some power to charge the battery.
So - if I add another solar panel 4 time 6V blocks, will it be enough for me to connect these in parallel? As each panel is connected using a Shotky diode, I suppose I can just solder the board in a parallel connection to make it work right.
Go to the @ WeatherPI Group: Weather Station / Type: Solar Array" section (way down)
Any thoughts?
PS: I found the exact same solar panels on a local shop. So I'll prolly go with these.
Question is if I solder the a multi-panel solar connector board myself, as this will probably be the fastest way for me to get it working.
Or even just solder these together :}
Could anyone provide me the part designation of the shottky diodes please? I know these are 40V / 3Amps.
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Post by SDL on Mar 8, 2020 11:16:14 GMT -8
Hi Smurphy,
Yes, those diodes should work. Which diodes are you asking for the specification? If you are talking about the multi control board, then they are:
DigiKey: 478-7814-2-ND DIODE SCHOTTKY 40V 3A SMA SD2010S040S3R0
If that is a SunControl board make SURE you have the 5.6V Zener connected across the incoming lines to the SunControl board. You WILL burn it out with more cells without that protection.
We actually use SolarMAX Lead to power our Pi3/4 systems in cloudy regions. Even here in Spokane Valley, we are using a SolarMAX LiPo system mainly because we were testing it.
GREAT build Blog. You do really, really nice work.
Best regards.
John
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smurphy
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Posts: 169
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Post by smurphy on Mar 9, 2020 0:36:01 GMT -8
Hi John, thx for the specs on the Shotky Diodes, that is fine. Why should I put a Zener Diode? The Panels are 6V only, as the ones you provide (These are actualy the same), and I will connect these in a parallel setup. Should not produce a higher voltage than the existing panels. Only thing that will change is the current that the 2 panels will provide. If I put a Zener diode in, what power dissipation will it require? Strongest I find are 5W over here.
If I look at the voltage provided by the solar panels in your Kit, it already goes up to 6.8V.  Is that not an issue?
I seem to have a power issue. Probably the switch on the suncontrol board, or is it the power that is too high?
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Post by SDL on Mar 10, 2020 15:58:33 GMT -8
When the battery is fully charged, the voltage will go up to ~7V which violates the specification on SunControl (not on SunAirPlus). You will eventually degrade and break your SunControl board without this zener diode. Check out the note on the SunControl product page: IMPORTANT NOTE:
When using the SunControl board, you need to look at the VOC (Voltage Open Circuit) of any other solar panel you have. If it is above 6V, you need to add in a 10W 5.6V Zener diode across the solar panels to protect your SunControl board and system. Connect the "+" end of the diode to the "+" side of the solar panel (or the line from the solar panel to the SunControl Board) and the "-" side to the negative ("-") side of the panel. This will get hot, so let it hang free in the air.
Unfortunately, you can’t just put 10 1W 5.6V Zener diodes in parallel. They aren’t identical and the one that is slightly lower will take all the current. You can, however, stack them in series to acquire the appropriate voltage and power dissipation. Such as stacking 2 5W 2.8V Zener diodes.10W 5.6V Zener: shop.switchdoc.com/products/10w-5-6v-zener-diodeBP |
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smurphy
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Post by smurphy on Mar 11, 2020 0:48:26 GMT -8
You should have put that Zener diode into the Kit. Because with the board (Solar panel) you deliver in your kit it actually reached 6.8V already.
I"ll see if I can find the appropriate elements over here, as I'd need them faster. Delivery to france is too expensive compared to the price of the zener diode.
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Post by SDL on Mar 11, 2020 17:44:58 GMT -8
Totally understand your comment. You should be able to find a similar zener over there. Anywhere from 5.4 to 5.8V should work fine.
BP
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smurphy
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Post by smurphy on Mar 14, 2020 4:19:21 GMT -8
I still have a question.
From the data I get from the current solar Array in place, I'd need at least double surface (means, 16W at 6V to cover for winter times.
In Summer and on Sunny days however, this will blow the Suncontrol board, as it is spec'd up to 1.8Amps, as the 2 panels would provide 2.6Amps in full sun (and the Panels actually deliver 1.327Amp on a sunny day). On a rainy day, as is the majority in my region, I barely have 1500Lux ilumination providing barely more than 150mA - this is not even enough to power the Station, as total drain for the station is around 180mA. With 2 panesl deployed, I would be able to actually power the station, and charge the battery a little (even if it won't be enough, but during the day I should be able to add ~1Ah to it even with rain.
What is the best way to go on.
1. Add a current Limiter (as I only require the full capability of the panels when the weather is bad/covered). This one limites power to 1.8A. means however it needs to dissipate 4W in full sun
2. Add a USB power supply to the Suncontrol board to charge the battery
3. Completely drop the solar-power and completely power the device through a External USB. I would actually provide 12V from my Basement to the roof, and use a 12V DC-DC 5V converter to lower the voltage. And, I would connect it to my Switch UPS in the absement, as that's where it would go out from (Using a Coaxial Cable to get the power into the Weather box.
Any advice?
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Post by SDL on Mar 16, 2020 13:44:52 GMT -8
Smurphy,
1. ) Not quite. That's not the way the SunControl controller behaves. If you try to have it charge more that 1.8Amps, the current is rejected and so the voltage climbs on the solar panels. SunControl self limits. The Zener diode protects the SunControl board and will drain the other 1A basically (in a sense). That's why you need a 10W Zener.
2) Could do that.
3) For systems in cloudy regions, you may have to move to our higher Solar power systems (with 100W solar panels) SolarMAX LiPo or SolarMAX Lead Acid. That's what we end up having to do in cloudy Washington State.
BP
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smurphy
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Posts: 169
Raspberry Pi: Yes
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Post by smurphy on Mar 17, 2020 1:43:45 GMT -8
Thx for the heads-up. I think that won't be necessary. Will probably go another approach. As I'll mount the Weather Stations at the old antenna's location, I can hook the antenna cable to a 12V power supply in the basement (Backed up by a UPS), and reduce the voltage at the Weather Station through a DC-DC converter from 12V to 5V. Using 12V here, as it will be a long cable and we'll lose quite some volts over the distance. At least this way I'll have a stable 5V power supply for the weather station. At least this way, I can control it somehow and should provide a 24/7 weather feed. The UPS in the basement only powers a 24port 1Gbps, and when the power is gone, powers it for about 4 hours. So plenty of reserve here.
I'll keep the forum posted once I have the equipment here. |
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