diy solar

diy solar

How much "Sun" do you actually get?

jasonhc73

Cat herder, and dog toy tosser.
Joined
Oct 1, 2019
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Location
Wichita, Kansas
You can have others tell you what they think your solar potential is, or you can just measure it directly yourself.

I found a weather station that has a w/m2 meter on it.
1000 w/m2 is "The Standard Test Condition (STC)" used for the output of a solar panel.

My "sol" meter (and weather station) https://www.wunderground.com/dashboard/pws/KKSWICHI416
Compare the Solar Radiation to the panel production

Ambient Weather WS-2902A Smart WiFi Weather Station with Remote Monitoring and Alerts
About $170 USD.
 
1000W is pure theorie. Practically you can be happy if you get 250W, because between measuring and actually getting it, there is a big difference.
 
1000W is pure theorie. Practically you can be happy if you get 250W, because between measuring and actually getting it, there is a big difference.
I think you misunderstand how the standard is. A room can have more or less, but a standard condition must be reproducible, so others can make the measurement also. 1000 lux per square meter is the standard, artificial or natural it is a nice simple round number. It's just the definition of the standard. Kind of like EPA standard for mpgs. It must be defined someway
 
the problem is when you discuss with salesman he uses the same "standard" to sell you the panel, and you usually end up with way too few power.
Currently if you take 1 square meter solar panel, it usually do not exceed 150W, 250W panels are already way bigger.
your sensor indicated today over 400W/h... So unless you work in a Lab, forget the 1000W/h per square meter.
 
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I have followed this site for a number of years. It shows the hour to hour production for almost 10 years. It is surprising the amount that is produced. Many people assume that the production spikes up immediately when sunlight hits the panel. Not so. A good production day looks like a bell curve.

Toronto solar prodution chart

I like to check https://www.windy.com/ to compare production to cloud cover.

In 2018 it looks like he had to replace the inverter. Click on the the Historical graphs and logs on the right for prior history. Click on the bars in the charts to get further info.

Historical chart

Pay attention to the winter months, particularly December. Now this is a grid connected system (no batteries) so he draws from the grid during the 10 day non productive periods. Off grid systems will need to supplement production in a different way, or have extra large batteries. As @JeepHammer said "you need 5 times the panel quantity that you will need in summer".

It is not a large system but he is paid something like $0.82 per KWH for another 10 years. If he upgrades he will loose that rate.
 
The weather station is cool, but aggregating the data over several years will be a big undertaking. Or, you can use SAM where the work (with local weather) has been done for you in a lot of locations.
 
The weather station is cool, but aggregating the data over several years will be a big undertaking. Or, you can use SAM where the work (with local weather) has been done for you in a lot of locations.
You don't need several years.
The data gets aggregated automatically to the cloud. All you have to do is sign up to the services.
 
The weather station is cool, but aggregating the data over several years will be a big undertaking. Or, you can use SAM where the work (with local weather) has been done for you in a lot of locations.

OR you can work in the oil industry in SouthWest Texas and EVERY FRICKIN DAY its HOT AND SUNNY ... followed by HOT and SUNNY ... it will be 78 today and .. wait for it .. SUNNY ... of course we normally hit our solar production requirements by 1000 every day for this entire complex ...
 
Now that you've had your Ambient Weather WS-2902A Smart WiFi Weather Station with Remote Monitoring and Alerts for a while... how are you liking it? Is it proving reliable or would your recommend anything else? I tried to look at the monthly data, but it returned "no data available". (Yeah... I'm thinking about getting one ? ).
 
Now that you've had your Ambient Weather WS-2902A Smart WiFi Weather Station with Remote Monitoring and Alerts for a while... how are you liking it? Is it proving reliable or would your recommend anything else? I tried to look at the monthly data, but it returned "no data available". (Yeah... I'm thinking about getting one ? ).
I have it going up to another PWS site also. (https://www.pwsweather.com/obs/JASONHC73.html)

It is very a good system. My objective was to see if I had enough wind to see if a wind turbine is a viable option. I don't think I have enough wind to justify a turbine, now that I can just look at the data and see the graphs.

The rain measurement system works perfect. It never needs emptied.

The solar lumens measurement is my favorite bonus with it.

The screen has a nice or stormy screen on it that is usually way off. But it is only basing the screen on the changing barometer. Falling pressure means rain and storms, rising pressure means sunny and nice. It should have a better forecasting system since it is a connected device uploading to the net all the time. It should read the forecast from somewhere to get the real weather forecast, not just use the barometric pressure to say it is about to storm, when there is no clouds in sight.
 
Thanks!
Did you go to pwsweather because the Weather Underground API is going away?
 
I use pwsweather just for the data logging. It appears to keep all the data.

Wunderkind seems to only have 1 days worth.
 
My "sol" meter (and weather station) https://www.wunderground.com/dashboard/pws/KKSWICHI416
Compare the Solar Radiation to the panel production

Hovering over the "i" gives "A measure of the severity of solar proton events as depicted in the NOAA Space Weather Scales" so I am not following the comparison with panel production. There might some loose correlation but photon measurement would be directly relevant.
 
Hovering over the "i" gives "A measure of the severity of solar proton events as depicted in the NOAA Space Weather Scales" so I am not following the comparison with panel production. There might some loose correlation but photon measurement would be directly relevant.
I think this has something to do with Current UV Risk. I have seen the screen show 600ish and the UV risk was 4, while other times I saw the w/m2 show 400ish and the UV risk was 6.

To me, it's only relevant in that it is the same scale that PV (photon voltaic) panels use.
 
I think you misunderstand how the standard is. A room can have more or less, but a standard condition must be reproducible, so others can make the measurement also. 1000 lux per square meter is the standard, artificial or natural it is a nice simple round number. It's just the definition of the standard. Kind of like EPA standard for mpgs. It must be defined someway

More than just a standard, 1000W/m^2 is very close to the amount of energy from the sun that lands on the earth. See section "Irradiance on Earth's surface":


If you have a 15% efficient panel, it will produce about 150W/m^2 when oriented toward sun directly overhead.
For my Bay Area location, a fixed orientation panel gets about 5.5 hours effective sun (average year round) so 825W/m^2 average per day.
Well, that would be if the panel was at STC, 25 degree C temperature. Which it generally won't be during a season when the sun is directly overhead.

So you have to derate from STC (25 degree panel temperature) to PTC (heated by the sun but cooled by a slight breeze, for 45 degree temperature.) Some but not all vendors quote this figure. But so long as temperature coefficient of voltage is given, you may be able to calculate it.


I've had some panels that were rated "optimistically" (some panels sold at a premium for higher measured performance, but didn't seem to hold up.) Other brands have delivered as promised, and held up well.
 
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