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Forum Index : Solar : 200W of panels for the educational experience
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| lizby Guru  Joined: 17/05/2016 Location: United StatesPosts: 3150 |
I live in Nova Scotia, where I can't imagine it will ever be economical to use solar panels in the winter (or spring, for that matter, since until right about now, early June, it's likely to be more gray than sunny, and on the chilly side). But I would like to have a play with some of the concepts. I have this WindyNation 200 Watt (2pcs 100 Watt) Solar Panel Kit , battery, and 2kW inverter. I am entirely comfortable with the wiring needed to set up testing, and with microprocessor monitoring and control with picaxe, micromite, or perhaps preferably because of wifi, ESP8266/ESP32 using Annex basic. What I don't know is the best way to monitor through the fine Nova Scotia summer how much power I'm getting from the panels--maybe over a kilowatt a day. I can set it up to charge the battery and to discharge under program control to any number of 120V plug-ins, including perhaps most conveniently a 50W LED shop light and/or a 300W halogen light. Suppose I'm charging the battery. At what voltage should I turn on one of the lights, and how do I monitor the power used (battery to inverter I assume)? And then at what voltage do I turn off the lights? I've seen poida's excellent projects, with the monitoring which he does. I will never attempt anything so heavy-duty. So for the sake of self-education, what is my best way forward? PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Monitoring should be easy with one of the low cost Turnigy watt meters. This provides readings of instantaneous voltage, current, and power, as well as accumulated watt hours. Very accurate, and good resolution. It can be powered directly from the system being monitored, or if you wish to retain the accumulated readings at night, from a small dry cell battery. I have two of these, and very happy with them. https://www.ebay.com.au/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=turnigy+precision+watt+meter&_sacat=0&LH_TitleDesc=0&_odkw=turnigy+monitor&_osacat=0 Cheers, Tony. |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
Not familiar with that exact controller but it looks Chyneese generic. Like them all, says you can turn the load on and off at set parameters. I have an old 400w panel up the back charging an N150 Battery. I have the fan and LED bar it is driving for ships and Giggles come on at 13.5 V which is any time the sun is out and turn off at 13. Basically it runs off the panel without discharging the battery. If I manually turn off the loads, even late in the afternoon the battery will hit float again in a minute or 5. My personal belief with SLA batteries especially is the float Voltages especially for Cyclic use are a bit High. They tend to cause the batteries to dry out quicker if not by boiling or gassing, by seemingly coming close to it. I prefer to use the lower float charge rates even if the battery is cycling a bit. In the way I am using them as above I think they are more floating that cycling due to the minimal discharge so maybe thats what I should be using anyway. IMHO, if the things are above 12.8, they are charged anyhow. Battery Voltages are a topic of endless debate so use whatever you feel is best. That's just my take on them and is as questionable as anyone else's ideas. :0) If you just want to bleed the power for fun and measurement, I'd suggest something like that. If you want to actually use the power at night, i'd still go the same way. You can manually over ride most of the controllers I have seen but I note they are all 3 Button where the one you appear to have is 2 Button. The 3rd Button on mine switches the load on and off so very easy to use that way. Yours might be a double press or a hold function somewhere. My first solar setup was 8 180W panels, what turned out to be a really Good PWM controller that are now sought after because of their functionality and an inverter and UPS. I powered a Fridge and a hot water urn pretty much this way. The old car batteries were never really discharged except for a 2nd controller I used to drive a relay for the fridge at night but it never took much power anyway. Running the urn came pretty much direct from the panels and in the end, was Direct as I set up to bypass the controller and power the batteries and Inverter direct due to the loads. I also ran a PWM controller so I could turn the max use of the urn down to what the inverter could handle and have it simmer once up to heat at about 50W. Enough to keep the water hot enough when turned up to boil in seconds but not enough to boil it all away before I could drink it. I learned a lot with that setup as I Imagine you will too. Funny how the availability and price of panels varys so much in different places. I went and checked out a couple of piles of panels yesterday sitting round at installers yard I get them from. One lot were 220W and I couldn't even be bothered picking them up. Even 250's are a bit common now and getting harder to sell. Mate in the US thought he hit the jackpot when he got given 4x 100W panels recently. Hard to find anything that small here unless they are " camping" panels but I did come across some 120's I think they were yesterday. Thinking about getting some of those as they are a curious panel that has a VMP of about 17v so could be good for battery charging. They are also about a metre square which is Odd. Made in Germany, I bet they were over $500 ea, maybe 1000 when new. Have fun with your setup. You know now you have something solar, it's going to be completely gray and overcast for the next month where you are now.... |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3150 |
Thanks for that. As far as I can tell, that module just displays the volts, amps, and accumulated amps. What I would like to do is be able to take a reading with a microprocessor so that I can produce graphs over time like those poida has (but on a much smaller scale as far as amps go). This sounds very like the setup that I intend, and the 13.5V and 13V upper and lower bounds will make a good starting point. I will want to figure out how to record the usage. Too true. I am jealous of the prices I hear about in Australia. Much higher in the U.S., and even higher in Canada. That would be very disappointing since we are now approaching what I call the season of perfection in Nova Scotia--day after day of beautiful weather, with only the occasional too-hot day. Starts to make up for winters here. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| bob.steel Senior Member  Joined: 27/02/2020 Location: AustraliaPosts: 188 |
You might check out Craigslist for second hand panels these days . Many systems are being replaced . Whether for micro inverters or larger capacity panels . The often sell the entire shebang with rails and hardware cheap. I was lucky here getting 20 off 250 watt panels brand new and a 5kw Solax inverter , rails and hardware for $500 AUD. Couldnt get there fast enough.Inverter had never been installed . Strange but I never look a gift horse in the mouth. |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 458 |
You may be surprised at how much power the panels give on cloudy days. I live on a mountain where we get clouded in quite often in winter. Mountain fog plus clouds. Depending on the light we can still get quite useful amounts of power. Not long ago the rain eased and the sky lightened a little and I saw nearly 700 watts going into our batteries. We have about 4kw of panels but on a good day the regulators throttle back pretty early in the day. Also our SLA batteries don't seem to like taking much more than around 60 amps anyway. I use a Blue coloured Battery Monitor, it logs all the stuff you want but will not output it to a graph. Sounds like you want a data logger, don't know much about them but I have heard of people using them to assess solar and wind sites. Have fun Pete |
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| Davo99 Guru Joined: 03/06/2019 Location: AustraliaPosts: 1578 |
I tend to be more amazed how much power 20+ Kw of panels DON'T give on cloudy days and in winter!! :0) I remember last year doing something like 80Kwh one day and less than 12 a couple of days later. There is a lot with orientation and some with tilt as well although not as much with that as often made out. You can vary from the ideal angle at the time by a significant amount and still be within a 10 % fall off from optimal. What has surprised me many times is how much power you can get with cloud edge effect. You look around and the light levels seem well down but the inverters are going off their nuts. I have seen several times outputs a touch over full panel rating. |
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