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Old 28-01-2020, 13:16   #1
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Favorite website for estimating solar production?

Do you have a favorite website for estimating solar production?

We are currently in the Florida Keys and our daily average production in January has been 6.6KWh, with a maximum day of 9.56KWh and a minimum of 3.45KWh. These numbers are recorded from my three Victron 100/50 MPPTs' "history" CSV output and dumped into a Google Sheet.

I've used this site https://www.suncalc.org/ to casually observe that when we are in New England for June/July/August the boat should be producing more solar energy per day even at that high latitude than we are in January at such a southern location. Sun angle and length of day coming in strong for the summer months!

Any solar calculators I've found so far give values in annual production, rather than breaking it down to monthly, weekly, or daily, based on time of year. Being mobile, that kind of matters
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Old 28-01-2020, 22:09   #2
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Re: Favorite website for estimating solar production?

I doubt you'd get more production with more sun. because you'll never produce more then you consume. with those numbers you must already br producing what you consume. because 600ah a day of consumption is huge.

moving to more sun with the same consumption will just produce the same amount.
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Old 28-01-2020, 22:45   #3
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Re: Favorite website for estimating solar production?

The old industry standby is PVWatts. It’s not the friendliest to use online, and it’s geared toward grid-tied systems so you’ll have to set some of the loss/efficiency values a bit different than defaults but it works.

The default output is a table by month, but under that there’s a link to download hourly for the whole year. Useful at least for showing relative production by location.
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Old 29-01-2020, 07:11   #4
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Re: Favorite website for estimating solar production?

Loud, I'm supposing that what you want for practical use is the ability to predict about what you are going to get from your solar array under your conditions, whether you are north or south at the time. There are bunches of variables unique to your setup. Perhaps the most practical approach would be an ammeter and a logbook, so you can record power generated under specific conditons (latitude, sunny, at anchor, month, etc.) at various times of the day. Within a year you would have enough data points to know the effect of a cloudy day or season or whatever interests you on power production, perhaps even as a percentage of your best case conditions.

Consider the possibility that using high tech ways of solving simple problems might create more barriers to your understanding your boat's solar system than they solve.
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Old 29-01-2020, 10:29   #5
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Re: Favorite website for estimating solar production?

I use PVWatts and it has given me useful results.

FWIW: I'm in NC and I get a little more solar production at home on sunny days in the winter than I do in the summer. Even with shorter hours. That's due to two factors:
• Better panel efficiency when it's cold and windy.
• I tilt my panels to optimize for: Summer 12° (almost Horizontal), and Winter 55°

You may not be able to get a 55° tilt on a boat but it makes it huge difference. I'd guess bigger than the cold weather.
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Old 02-02-2020, 16:54   #6
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Re: Favorite website for estimating solar production?

Quote:
Originally Posted by smac999 View Post
I doubt you'd get more production with more sun. because you'll never produce more then you consume. with those numbers you must already br producing what you consume. because 600ah a day of consumption is huge.

moving to more sun with the same consumption will just produce the same amount.
I have no problem using electricity. It's simple, more frequent longer hotter showers. Followed with air conditioning.
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Old 02-02-2020, 16:55   #7
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Re: Favorite website for estimating solar production?

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Originally Posted by Dsanduril View Post
The old industry standby is PVWatts. It’s not the friendliest to use online, and it’s geared toward grid-tied systems so you’ll have to set some of the loss/efficiency values a bit different than defaults but it works.

The default output is a table by month, but under that there’s a link to download hourly for the whole year. Useful at least for showing relative production by location.
Thank you - I'll give it a look.
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