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Solar Panel Questions (lemmy.world)
submitted 2 days ago* (last edited 2 days ago) by [email protected] to c/[email protected]
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I have recently purchased a home with solar panels. The previous owner didn't have a ton of information on them as she inherited the house from her mother who passed away. She has the purchase agreement, but the company that did the installation in 2014 has gone bankrupt (in 2020).

I'd like to somehow figure out how much energy I'm getting out of the panels. I got information from the previous owner on their electric bill, which shows me I won't be paying much. But that doesn't really answer my question about electricity generation.

Looks like I have 14 solar world Mono Black panels with model number 275.

Any advice on how I can go about figuring out exactly how much energy generation I'm getting?

Ancillary Information: the panels are owned outright. They were originally purchased with cash so no loan or lease on them.

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[–] [email protected] 17 points 2 days ago* (last edited 2 days ago) (2 children)

Looks like the model name is the wattage. Your panels are each making a max of 275w. With 14 of them, the max power they will generate is 3850w, or 3.8Kw. That's a pretty small solar deployment, about 1/4th the size of a array intended to provide full power to a US home. Still nice to have, but sized more to offset power costs than to eliminate them.

That means if you have one hour of full sunlight hit your panels, it will generate 3.8kw of power. If you go to this site it will estimate how many sunlight hours your roof will get per year. Multiple the sunlight hours by 3.8Kw to find your total possible power generation per year.

To find out how much you'll save, you need to know how much a Kwh costs from your local power company, likely between $0.10-$0.30/kwh.

So just with made up totals, if you get 1000hrs of sunlight/yr, you will generate up to 3,895kwh. At $0.10/kwh, you'll save $389.50/yr.

[–] [email protected] 1 points 16 hours ago

That means if you have one hour of full sunlight hit your panels, it will generate 3.8kw of power.

I think you mean kWh of energy, not kW of power, since you multiplied it by time.

[–] [email protected] 9 points 2 days ago (1 children)

Thank you! This is very comprehensive. I have a place to start now.

[–] [email protected] 2 points 1 day ago* (last edited 1 day ago)

Glad to help. I've been investigating my own solar install, so have been digging into the specifics a lot.

Note that the above are the "best case" numbers. Panels can put out less power for lots of reasons. They tend to lose a little bit of efficiency when they get older. Think 1%/year, but that's just a rule of thumb. Being dirty can affect them, cloud cover, angle and position, and hilariously counterintuitively, if they get too much sun. Solar panels get less efficient the hotter they are, so an especially sunny day will lower the power output.

Leads to some complex effort to optimize, but honestly its power that just hits your house for free. That's a fine thing in any circumstance.

[–] [email protected] 9 points 2 days ago

Pictures of the system and any identifying stickers would help. There should be an inverter somewhere between your panel and the solar panels.

[–] [email protected] 6 points 2 days ago (2 children)

As others have mentioned look for the inverter. It is also a good idea to call an electrician, it'll cost you, but they can double check everything is still in good working order and can answer all questions.

[–] [email protected] 6 points 2 days ago (1 children)

Call the inverter manufacturer first. As others said, they most likely can help you connect it to the internet and check to see what's working and what isnt. With their help, even if you do need to call an electrician, you'll at least know what the issue is and can make the electrician's job easier, faster, and probably cheaper for you.

[–] [email protected] 2 points 2 days ago

Good idea!

[–] [email protected] 2 points 2 days ago

Thank you. I will ultimately get a professional in and am hoping to do some... Homework first. This helps.

[–] [email protected] 6 points 2 days ago

I know my panels connect into a box on the side of the house that I can connect to and check data on power generation. Do you have any kind of box like that on the house that you can't id?

[–] [email protected] 4 points 2 days ago (1 children)

Around here it is common that the inverter collects such data and makes it available in a mobile app or on the manufacturer's website.

So you would look for the make and model of your inverter first.

[–] [email protected] 1 points 2 days ago

Great idea will do.

[–] [email protected] 3 points 2 days ago (2 children)

My inverter has a setting for a static IP adress and an ethernet connection, so if I browse to that adress I can read some statistics of previous usage.

[–] [email protected] 1 points 1 day ago (1 children)

That's a neat feature. Most of the ones I've seen just offer "cloud monitoring" with no mention of local access. Can I ask what inverter you have?

[–] [email protected] 1 points 18 hours ago

I have a Steca brand, model Stecagrid 5503.

[–] [email protected] 1 points 2 days ago

Interesting I'll have to take a look.

[–] [email protected] 2 points 2 days ago (2 children)

The 275 number probably isn't (just) a model number but the max generated wattage. That'll give you some idea of the generated power. In practice you'll never hit that number but I just got a peak of 315w at noon on my 355w rated panels.

[–] [email protected] 1 points 1 day ago

Yea most roofs are unfortunately not positioned ideally for PV.

[–] [email protected] 2 points 2 days ago* (last edited 2 days ago)

Indeed, it's actually Wattpeak. For my work I make a difference between actual Watts and solar Wattpeak. I normally multiply by 0,75 to get the MAX power. This max power only occurs around noon as the sun goes up and down again. For energy in my home (Lithuania) I hope to get in the summer with 1kwh/M2/day from the solar panels.

There are geological overlays graphs available that give indication on how much kWh you can get. Solar atlas is one of them. Look for kWh/kWp, multiply it by your solar installation size and you have your average available intake of energy. You can find the kWh/kWp on average per year,month and day. So you know in winter that you produce a lot less than summer