What are real output from solar panels?
What are real output from solar panels?
Hello everyone and happy holidays!
I'm interested in photovoltaic panels, it's the future and all!
But with the subsidiaries and the general enshittification of search engines, all search results about photovoltaics leads to sites with wildly misleading information, IMO.
I don't care about a 3kWc system with installation. What even is a kWc (I know what it is) and why is nobody explaining how much power the panels would typically yield instead? Per month? During the day?
I guess it is less selling if your installation is generating near nothing in December when you need it the most?
Okay sorry, rant off. My question is, where can I find reliable information about how much panels generate every month, during the day?
I know places have more or less sun, but that's quite easy to figure out if you have the numbers for any place.
🌞
Edit: I don't need a web calculator for how many panels I need. I'd like to know roughly how many watt a typical panel produces a specific day (or better hour) in the year.
Edit2: I am not looking for how to install or calculate a typical solar panel setup. I'm looking for the typical real world output of solar panels around the day and year.
Edit3: got my information, thanks oo1@lemmings.world ! You all can now continue explaining how many panels a home needs or what a kwh is, Merry Christmas to you all!
There are web calculators where you put in your latitude, angle of the panels and total kWp of your installation. It then spits out a kWh prediction for the year. Might still be shitty to find a good one tho. I can tell you that the system i installed at my parents house with 10 kWp has produced 8.4MWh of AC output this year. I live in southern Germany which is around 48° latitude and it was pretty gray and rainy this summer so could be much better.
This is daily total generation in kWh split up by how much went into the battery vs directly into live usage in the house vs exported to the grid.
This shows the sources of all the electricity that the house used over the year on any given day. Red being imported electricity.
This. There is too much local variation in sunlight angle and weather to give a straight answer. An easy method is to take the rated output and multiply by 0.2, but even that is merely a rough average over a year.
But there should be data on weather and climate variations. So theoretically you could include that data into the calculation. Theoretically. Who's gonna do it?
Yeah, solar panels put out power in proportion to the light that hits it and its efficiency. The latter is in the specs but the former requires knowing how it will be installed before you can determine expected output.
Some calculators can also consider weather predictions (cloudy days, etc)
Some calculator sites;
https://www.omnicalculator.com/ecology/solar-panel
https://pvwatts.nrel.gov/
https://pvfitcalculator.energysavingtrust.org.uk/
Thanks but link 2 and 3 doesnt work for non US/UK? Adress needed
Link 1 seems completely useless, like no I don't want to know how many "panels" I need for an installation.
For every month? That would be helpful, just then need to convert the energy (kWh) to power (W) which is easy.
You can't convert the kWh to W, that's not how it works. The amount of sunlight is highly variable during the day and the way the sunslight gets converted into usable energy differs a lot depending on the installation.
Normally those calculators assume you can connect the solar installation to the grid and use the grid as a buffer. So when there is sun and you're not using it, you deliver the power back to the grid. And when there is no sun, you get your power from the grid. When there is a little sun, or you're using a lot, you use some energy from the solar panels and some from the grid.
It starts getting complicated depending on how your local grid works. Often supplying back energy to the grid means the power provider credits you a certain amount. Depending on your contract, this might be a day price or even hourly. Or it may be a fixed price. This often means you pay a lot more using power from the grid then you get back pushing power back into the grid. So you need to think more in terms of money and using the energy in a way that's cheapest.
If you are thinking about an off grid installation, the amount of power is almost always dependent on your equipment and not so much the solar panels. For example you can charge up a large bank of batteries from the sun during say a week. Then when fully charged, you can draw huge amounts of power from them till the bank is empty. But depending on the batteries used and the inverter used to convert DC into AC, the amount of amps it can push can be limited.
When thinking of something simple like a use case where you directly use the DC from the solar panel, the panel specs always include the Wp value. You can use that to calculate the exact amount depending on your location, time of day and angle of the panel. Weather services these days also include a watt per square meter of solar energy for different locations, which is useful. And keep in mind it only works when it's sunny, with clouds the output drops a lot.
I've seen huge swings in my pv installation year on year. So it isn't a sure thing how much energy you get from the sun.
I edited my comment and added a screenshot from my grafana dashboard to show the trend over the year and some other numbers. Batteries are expensive but they are worth imo. ~75% of the electricity usage of this house with 6 people comes from its own solar production. There is however a cut off for how much battery capacity makes sense. To get the last 20% of self sufficiency you would need a disproportionally larger battery to make up for long periods of low sun. so 80% is as good as its gonna get while staying cost effective.