Re: solar panel


Sv Garulfo
 


I usually find that a slight overcast yields better output, but i don’t know if it’s related to the potentially lower temperature of the panels or the dispersion of the solar rays.

My skin also agrees; an slight overcast is an easy way to get sunburnt. 

I also think some manufacturers promote better guaranteed output over the life of the product, even if it means having to put forward a lower power rating to start with. So your panels may start with a better output than promised and end within the advertised  range. 

Scott,
With 900W of solar, occurrences of 35+ amps are pretty rare for me. It needs an almost vertical sun. I don’t think you’re missing out much.

Best,

Thomas
GARULFO 
A54-122
Huahine, French Polynesia 



On 20 May 2021, at 18:29, Nick Fowle SM 404 Rascal via groups.io <svrascal@...> wrote:

I have similar experience with my two LG360s on the arch. According to Victron I have benefited on a few days in excess of 900wts  peaks , and regular days in excess of 800-840wts peaks. Ironically the 900 days are not highly correlated to the highest total power days, where I can get around 4kwh out of the panels. However with the weather changing down here the overall yield has declined significantly recently, but I do continue to get some days of peak output which is slightly higher than rated, but the total yield  during the day rarely gets above 3KWh and is bound to decline further. 

The Bimini ones (2*220) rarely exceed rated output, but when they do, they can exceed the combined theoretical total by around 10-15%. They are not as consistent given shading etc . As per the LG’s there appears (according to Victron) to be very little correlation between peak power days  and highest overall yield during the day so now I largely ignore peak power. 

Best days I’ve had around 5.8-6.2 KWh  from the four panels, and these were sailing days back in early April, not on anchor. Now, on a good day here in Carriacou I get around 4-4.75kwh and last week , as low as 1.5kwh across the four. The weather was pretty special in Southern parts of Grenada last week. 

Both sets are wired in parallel. I recently switched the Bimini ones from being in series (as per instructed ) to parallel but  haven’t a really seen a  material difference in performance. It’s hard to make any meaningful comparison/ analysis on the switch over mainly I think due to changes in the weather here in Grenada over the past few weeks. This week the weather in Carriacou has been pretty good but hazy (Sahara sand apparently) but the Bimini panels now in parallel have performed worse than when in series. Will continue to monitor, too many variables to make any meaningful conclusions right now. 

I have to run the genset roughly once a week at anchor, mainly for the water maker. My 3KW Quattro overheats after about 30mins if I am running the water maker off the Quattro/ battery bank alone. As the season changes further, the genset hours will obviously increase, until I move on after AZ2 jab scheduled for mid June. 

Bill , if you come up with a plan for the insulation please share. Like you the fridges and freezers are a significant portion of the overall daily consumption, even when taking into account that I cook / bake on electric. 


Nick
SV Rascal
SM 404
Tyrell bay, Carriacou 

Sent from ProtonMail for iOS


On Thu, May 20, 2021 at 9:29 PM, Bill Kinney <cruisingconsulting@...> wrote:
Scott,

Dean has given a great explanation of how solar panel manufacturing tolerances and marketing interact.  We bought our panels when they were new on the market, and we lucky enough to have gotten a pair with well above rated output, but it's a crap shoot. We will see above rated output most sunny days for about an hour either side of local noon.  But of course peak output is not REALLY what matters.  Total daily energy output is really what we care about.

Our two arch mounted, horizontal, 315W rated, panels generate between 3.25 and 3.5 kW-hrs on a typical sunny day in south Florida in the spring.  In June we will see as high as 4.0 kW-hrs.  This is on those days when our batteries are accepting a bulk charge all day.  Our normal daily power consumption at anchor is about 6 kW-hrs, so the solar panels give us a bit more than half our total usage.  We run the generator every other day to bring the batteries up to about a 93% charge in the AM, and the solar panels then bring them up to 100% full by 14:00.  It is a set up that has worked really well for us.

Most of the 6kW-hr power usage is refrigeration.  We run two freezers, and a fridge, and the Amel installed insulation is not the greatest. A serious upgrade of the insulation is on our wish list.

Bill Kinney
SM160, Harmonie
Hollywood, FL



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