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Installed an 80 watt thin flexible solar panel and mppt controller. Getting up to 7.2 amps at peak sun times. Nice to be free of the power cord.

 

Very nice bbay. Can you tell us more about your setup and what it performs like in overcast conditions? I'm keen for something similar myself although I also want a semi-portable option so as I can remove it when I am racing.

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Isn't watts/volts=amps the theoretical max? i.e 80/12=6 and a bit.

Correct, but now do the math again using a higher voltage, like 13.8 or maybe a tad more even, because it depends on what the panel/mppt controller is punching in. 12V wouldn't do much in the way of charging the bank.

And yes, Panels lose performance over time. 20yrs time, they could be as much as 50% down in performance, but it does depend on panel quality slightly. So a cheap panel today may not be so cheap against an expensive one in 15yrs time.

This is one reason why Russel Norman's idea of Solar panels for 30,000 homes is a stupid idea. People will have just paid off their $15K loans and at the time that they then expect to make a profit from supplying excess power, the panels will need replacing. Not to mention Battery banks if they went that far, although I expect they wouldn't have.

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Its an 80 watt panel which are $225 on trademe. You can get more efficient panels (19%) from the same guy which means they are a bit smaller. The above panel fitted my dodger roof perfectly so I did not need the extra small size.

This panel seems to work well even at late evenings , early morning. I drained my batteries down to 12.6 volts after installing the system and when I took the towel off it pumped in 7.2 amps for a while then went down to 3 or 4 and then 0.3 at 14.2 volts then 13.8 volts.

We are going for a cruise later in March up around the Bay of Islands so I'll be able to report on how it copes. We are a simple fit out though.

http://www.trademe.co.nz/Members/Listin ... ber=829264 panel

ahttp://www.trademe.co.nz/Members/Listi ... er=3073130 controller

I like these mppt controllers because the panels can be hooked up in series so as to keep the amperage down so can use smaller wires. I get 19.95 volts. Supposed to give 4.45 amps but apparently our sun is a bit stronger than what they use to rate the panels (20%) so 7 amps is close.

Its hard to know how many amps it gives because I need to run the batteries down to get it to pump.

So 19.95 / 13 =1.5346 x 4.45 amps= 6.8 amps plus a bit more for our brighter sunshine so the above 7.2 amps is in the ballpark. I hate doing maths in front of a bunch of Engineers! :lol:

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I like these mppt controllers because the panels can be hooked up in series so as to keep the amperage down so can use smaller wires.

You can do that with a standard controller too, but the thing with the mppt is that it offers the best load to the panel over its operating range, which constantly varies, so the maximum power output curve as the Sunlight intensity changes on the panel.

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Isn't watts/volts=amps the theoretical max? i.e 80/12=6 and a bit.

Correct, but now do the math again using a higher voltage, like 13.8 or maybe a tad more even, because it depends on what the panel/mppt controller is punching in. 12V wouldn't do much in the way of charging the bank.

And yes, Panels lose performance over time. 20yrs time, they could be as much as 50% down in performance, but it does depend on panel quality slightly. So a cheap panel today may not be so cheap against an expensive one in 15yrs time.

This is one reason why Russel Norman's idea of Solar panels for 30,000 homes is a stupid idea. People will have just paid off their $15K loans and at the time that they then expect to make a profit from supplying excess power, the panels will need replacing. Not to mention Battery banks if they went that far, although I expect they wouldn't have.

 

Solar panels on houses that are hooked up to the grid do not normally use battery banks, instead they use the grid as a bank exporting excess power during the day and importing it at night, which means a lot less expense and maintenance. Also panels will often still perform to their rating after 20 years , after dropping perhaps 10% from the performance when new. I think it is a good idea on houses although solar hot water should come first. :thumbup:

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I agree that hot water heating would be by far the better scenario. With it being cheaper, it may have a greater number interested rather than just 30,000.

But you will find many panels are significantly down, as much as 50% down by 20yrs. It varies and as I said, it is where the money starts coming in to a panel. Cheap is cheap for a reason. But cheap is the biggest selling point in panel these days. Plus it depends on the type. And I am also talking of the current technology. The new stuff still to be seen on the market may or may not change that.

Oh and the other issue with having a Solar installation and having power to sell, is that the supplier ends up selling at the Wholesale rate, not what they pay for power. So unless you use a lot of power 24hrs per day, you will struggle to actually make money. That's the thing with Solar, you need to have the system working at capacity to be economical. No point in having lots of Panels and only idling the system or not working at all during the day when you are at work for instance. Which of course would be when the least power would be needed back on the grid.

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I'll get back to you in a couple of days Ferrari. Hey Wheels most panels are normally guaranteed for 25 years to have 80% of their rated current.

This thin panel is so nice, hardly notice it on the yacht.

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I got 80watts of panels on the marauder. Got 2 x 6v batteries with 220amp hour capacity

 

Runs everything including the electric frige and dumping power most of the time

 

Capacity is king, so if u go big panels go big batteries as well

 

It is great not having to worry about power

 

Now where is that water maker......

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Depends on the type of regulator, but some, especially the older ones, do exactly that. They dump the current to a load which I remember on some, where no more than a heater element. The idea was to keep a load on the gen so it did not take off freely and throw itself apart. Now days, we have decent cheap electronics that can handle high currents with ease and the charge reg's are a lot more complex and trickle charge as well as break the gen when no current is needed. Still "wasting" power as such, but not the heat due to no heating element being the load, but no place else to easily send it. If you wanted to get complicated, a design that switched the load to a Hot water element or some other demand could be designed, but it tends not to be worth the cost usually.

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Clever devices! Looks like it will look after the batteries really well. Mine has a "load" outlet that can be set up to switch itself on at sunset and off again at dawn which I have hooked up to the anchor light. I might run the Nav light over as well and put a switch in line so I can choose the Nav or the anchor light to come on. This "load" is just from the batteries obviously.

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Clever devices! Looks like it will look after the batteries really well. Mine has a "load" outlet that can be set up to switch itself on at sunset and off again at dawn which I have hooked up to the anchor light. I might run the Nav light over as well and put a switch in line so I can choose the Nav or the anchor light to come on. This "load" is just from the batteries obviously.

 

Yeah the Tracer controller I chose has the same option. It also has an option to plug in a display that shows the current/voltage from the solar panel, charge state of the battery and the current drawn from the "load" port. The only slight concern I had on mine was the manual indicated the controller has an ability to equalise the batteries. I was a bit worried about the battery releasing explosive gases in a confined space during this phase.

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Yes mines a Tracer. Agree it would be good to have contol over the equalization phase. I guess these are designed for street lighting.

I guess we could just have a switch with a load like hot water heater ( a kettle would be great) attached to the batteries and then just switch it on when there's plenty of power in the system and lots of sunshine. That is to save wasting the power.

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We've had solar hot water for 9 years.Set up cost $4500.Saves about $300 a yr.On 3rd panel.Next panel won't be warranty and won't be cheap.Plus electrics ,pump etc.Do the maths.As we eventually discover there's nothing for nothing.Like the Greens Dream solar is an expensive nightmare when it stops.Maybe the Greens get a commission from the solar manufactures just like the temperance league was secretly funded by breweries.The greenies will bring us to our knees if we don't look further than our noses!

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