#172506  by Nut17
 Thu Apr 29, 2021 12:07 pm
I took a photograph of the controller connected to the front three X 200 watt panels in late December at midday and recorded just over 43 Amps being produced. Potentially over 80 amps if I had the other three panels mounted and hooked up to the second controller. The motorhome is parked in exactly the same position and I have just photographed the controllers in a clear blue sky. Less than half the output - as expected. Added to this reduced production is the correspondently far fewer hours of sunlight that the panels are able to produce significant current. I estimate that in clear conditions the solar harvest over 24 hours in mid winter compared to mid summer would be around 25%. To exacerbate this situation the number of hours that electrical current is being drained from the battery without the benefit of solar input to compensate this drain is almost doubled. It is at this time of the year that having as much solar that will fit on your roof is a really sensible option. ;)
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A3EC7CC6-1CE5-4A95-8A35-489F62331BD2.jpeg
Today at 11.30 am
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December 2020
 #172507  by Neddy
 Thu Apr 29, 2021 5:09 pm
Interesting topic. Solar irradiance insolation data are available averaged over the last 22 years. This gives the daily energy in KilowattHours per square metre per day. Panels with a 20% efficiency, say, would capture 20% of this figure. Data is not available for Hastings, but the following figures are for Tauranga.
December 6.58kW/M²/Day
May 2.5 kW/M²/Day (about 38% of average December sunlight.)
IF the panels were to be tilted 53°, the May irradiance would increase to 4.12 kW/M²/Day.

Neville.
 #172508  by Gadget
 Thu Apr 29, 2021 5:20 pm
For those interested - NIWA offer the SolarView site free of charge. There, you can input your location and panel bearing/angle for comparisons. The below images show the difference in generation capacity between the different times of the year. The units are kWh/m2, but this is largely irrelevant when using it simply as a comparison tool.

This one is with panels flat (0 degrees):
0deg.png

And then with them angled at 45 degrees:
45deg.png

As you can see (click on the images to make them bigger), tilt plays very little part in the height of summer when the sun is high in the sky (actually makes it worse), but in winter, it can make a substantial improvement - as above, in winter, the cumulative day totals (with flat panels) are about 25% of summer values - by tilting the panels you can get closer to 50%.
 #172509  by Nut17
 Thu Apr 29, 2021 7:22 pm
I always like to witness real live results and in particular the extra daily hours of draw down over the winter that adds to the issue of much reduced generation.

( You need to update your signature Ben - It has been a while since you have had a Sante Fe in your fleet !!)
 #172510  by ianganderton
 Thu Apr 29, 2021 7:24 pm
Not exactly irrelevant. My understanding is solar panels are rated by testing them under 1kWm2 so if there are 5 kWm2 hours average predicted and your solar panel is 300w you could expect 1500W of power generation in the day

Sorry if I haven’t got the units correct because I can’t see the post on my phone while typing this but you’ll get the gist


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 #172511  by Gadget
 Thu Apr 29, 2021 7:26 pm
Sorry I know it’s not irrelevant as in it relates to ultimate generation, but from a comparison point of view (between seasons, elevation etc) it is - it’s just the numbers that need to be directly compared.
 #172512  by Paul-Carter
 Thu Apr 29, 2021 7:50 pm
Well its put up or shut up time for my system. We are off for our wairarapa ramble in the morning. So it will be the first time the system has fired a shot in anger in autumn conditions.
The new brakes aced the COF
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