Amen
Well-known member
Kevin Means said:
So at peak 45 amps ..is that per panel or total? That would mean you're putting out a total of 270 amps of power at peak? Sorry if I don't understand it correctly.
BTW..Nice looking rig!!
Ken
Solar panels
- Thread starter Sunseeker2016
- Start date
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So at peak 45 amps ..is that per panel or total? That would mean you're putting out a total of 270 amps of power at peak? Sorry if I don't understand it correctly.
BTW..Nice looking rig!!
Ken
PJ Stough
Well-known member
I believe that Kevin is getting 45 amps total output.amyken said:
JDOnTheGo
Well-known member
One can safely assume 45 amps total. 960 watts at a charging voltage of 13.5 volts is about 71 amps. Given the losses of flat mounting, 45 is reasonable.
I have two 327 watt panels (650 watts total) which are flat mounted. On a good summer day, total actual output is just over 80% of rated power (~550 watts). On a good Arizona winter day, total actual output is about 50% (300-325 watts). The number of good "sun hours" during the summer is greater than the winter as well.
There is a price to pay for flat mounting as well as for the sun sneaking down low on us during the winter months. This is why many people who flat mount have more total capacity than they actually require.
I have two 327 watt panels (650 watts total) which are flat mounted. On a good summer day, total actual output is just over 80% of rated power (~550 watts). On a good Arizona winter day, total actual output is about 50% (300-325 watts). The number of good "sun hours" during the summer is greater than the winter as well.
There is a price to pay for flat mounting as well as for the sun sneaking down low on us during the winter months. This is why many people who flat mount have more total capacity than they actually require.
Kevin Means
Site Team
Hi amyken... they are correct, the six panels are putting out a total of 45 amps in direct sunlight. Those are instantaneous measurements, so as conditions change, so does the panels' output. If clouds block the sun, you can see the output drop. As the sun rises in the morning, you can see the output increase, and as it sets, you can see it decrease.
How multiple panels are wired, and the type of controller you have will also affect how much power you can get out of your panels, and how long you can get it. Yeah, there's a bit more to this solar stuff than just slapping some panels on the roof.
Kev
How multiple panels are wired, and the type of controller you have will also affect how much power you can get out of your panels, and how long you can get it. Yeah, there's a bit more to this solar stuff than just slapping some panels on the roof.
Kev
JDOnTheGo
Well-known member
As you said, available roof space is a major factor. Additionally, the desired voltage and mounting method CAN big factors. From there, unless I am forgetting something, I think it largely boils down to which myths and opinions you decide to believe.
I have a huge amount of space and went with large and very high voltage (60 volts) panels and relatively small size cables (thanks to the high voltage). I've seen some not like this idea because the warranty might not cover the installation (imo, silly for such a low cost item) or are scared of the higher voltage. Of course, this voltage requires an MPPT charge controller - some don't like that and want something less complex and less costly.
It really is a system design issue. If a person chooses to just buy a kit and skip the system design, they get what they get. If one chooses to actually design, you get to evaluate the pros and cons of every option and then choose the options that work best for you.
I have a huge amount of space and went with large and very high voltage (60 volts) panels and relatively small size cables (thanks to the high voltage). I've seen some not like this idea because the warranty might not cover the installation (imo, silly for such a low cost item) or are scared of the higher voltage. Of course, this voltage requires an MPPT charge controller - some don't like that and want something less complex and less costly.
It really is a system design issue. If a person chooses to just buy a kit and skip the system design, they get what they get. If one chooses to actually design, you get to evaluate the pros and cons of every option and then choose the options that work best for you.
Kevin Means
Site Team
Shading is a crucial consideration when trying to decide what size of panel(s) to install on an RV's roof. Solar panels are made up of interconnected solar cells, and to a large degree, each cell is dependant on the other cells to enable the panel to generate its full output. For example, if a panel were only 10% shaded, (2 out of 20 cells), you'd think that the panel's output would be reduced by only 10%. In reality, its output will be reduced by about 90%, rendering that panel, and any others that are wired in series with it, useless.
Just because there's physically enough room to mount larger solar panels on an RV's roof, doesn't mean it's the best way to go. We've got quite a bit of room to play with on the roof of our 43 foot coach, but look at the picture I posted - at how our panels are installed. They're staggered between other objects on the roof, so as the sun rises and sets throughout the day, shadows cast by those other objects won't shade the panels until late in the day - when panel-output is nil anyway. If the panels are so big that they must be mounted right up against an air conditioner, vent or other object, just so they'll fit on the roof, they'll quickly become shaded and will no longer be able to recharge the batteries.
Kev
Just because there's physically enough room to mount larger solar panels on an RV's roof, doesn't mean it's the best way to go. We've got quite a bit of room to play with on the roof of our 43 foot coach, but look at the picture I posted - at how our panels are installed. They're staggered between other objects on the roof, so as the sun rises and sets throughout the day, shadows cast by those other objects won't shade the panels until late in the day - when panel-output is nil anyway. If the panels are so big that they must be mounted right up against an air conditioner, vent or other object, just so they'll fit on the roof, they'll quickly become shaded and will no longer be able to recharge the batteries.
Kev
John Hilley
Well-known member
William52 said:
Actually only 450ah of battery. To get 12 volts the 6 volt batteries have to be connected in series, thus two sets of series connected batteries connected in parallel.
JDOnTheGo
Well-known member
William52 said:
This is a recurring question that I am never sure how to answer. With solar on a S&B's it is a bit easier. Firstly, there is a huge "convenience" benefit that is impossible to put a number on. This convenience includes quiet. There must also be a dollar value as well but I don't think it is easily determined. One option, I suppose, is to multiply all the Kw's that the meter says has been created by the going rate for electricity. However; that probably is not the actual cost as you would have likely had to run the generator for these Kw's if you did not have solar and I suspect generator electricity is more expensive than power company electricity. Then one probably also needs to factor some amount of generator maintenance in. Someone once told me that without solar they needed to run their generator four hours per day. I saw another person report that they ran their generator 14 hrs/day over a two week period (WOW!). I can only guess that running a big generator 2-3 hours per day would require at least a gallon of fuel. So, at $3/gal, that is something around $1,100/year.
In my opinion, my solar paid for itself after about two weeks of quiet (because quiet is valuable to me). If someone is more of a facts person, it certainly paid for itself within the first year.
Obviously the calculation would be different for occasional use.
ArdraF
Well-known member
- Joined
- Feb 12, 2006
- Posts
- 10,695
JD, we figure we use about 1/2 gallon of diesel per hour to run the 10kw generator. And, you're right. That 14/hr. day amount is unusual. Maybe they use their air conditioner when boondocking or have some other need such as power for a hobby or business.
ArdraF
