Small Solar System For Sign

[jaggedben]

Didn't the OP say that his customer insisted that the PV module be pointed straight up? That seems silly to me, but the customer is who signs the check.

Missed that bit.
He can tell the customer that his choices are as follows:
- angle the panels
- spend something like 5 times as much on solar panels that take up 5 times the space
- not have the light guaranteed to stay on all night in the winter

 

[wwhitney]

- spend something like 5 times as much on solar panels that take up 5 times the space

The interesting thing about the numbers I posted earlier is that it wouldn't be 5 times, it would just be 2 times. Not quite as bad as expected.

Cheers, Wayne

 

[jaggedben]

The interesting thing about the numbers I posted earlier is that it wouldn't be 5 times, it would just be 2 times. Not quite as bad as expected.

Cheers, Wayne

That's what I get for not reviewing your numbers again before posting.

 

[wwhitney]

That's what I get for not reviewing your numbers again before posting.

Could use a closer look to be sure I used PVWatts correctly and interpreted the output correctly.

Cheers, Wayne

 

[Ravenvalor]

Per PVWatts, for a random point in NC (35.5 degrees Latitude), a panel straight up will see an average of 2.4 kWh/m²/day of incoming sunlight in December, vs 7.0 in June. So that's a big ratio, but December is not 0.

Tilting it just 10 degrees to the South changes the December number to 3.0 with no change in June, so is a significant improvement. (20 degrees is even better, 3.5 and 6.9.) Maximizing the minimum monthly average irradiation requires jumping up to a 55 degree tilt, for which December is 4.6 and July is 4.8 (and the peaks are in the spring and fall).

Obviously a crude analysis, looking just at monthly averages of incoming sunlight.

Cheers, Wayne

Thanks everyone for helping me design this small system.
Will you be kind enough to take a look at my preliminary design please?
Thanks again,

2 - Renogy Monocrystalline, 50watt, 12volt, 16.9% efficiency, 24" x 24" panels mounted facing straight up. Customer will clean monthly.
1 - DEKA 100amphour, deep-cycle, marine battery, buried underground in a nema 4x enclosure.
1 - Morningstar Sunlight 10A regulator.
2 - Sylvania 3", Slim Cube, 12v, DC, 8.2watt, flood lights. These will run 8-hours per night but I can probably talk customer down to 6.

 

[wwhitney]

Thanks everyone for helping me design this small system.

You quoted my post, but I don't actually have any experience designing a system like you propose, just a passing familiarity with PVWatts. Approximate latitude and longitude of the installation would help a designer use PVWatts to figure out the performance of your system.

Cheers, Wayne