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Old 18-10-2012, 00:42   #16
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Re: Solar Setup Adequate?

Immensely helpful!!

That's funny, I was just looking at the link to MacGregor's mods this afternoon - the rest of the site is just great.
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Old 18-10-2012, 05:00   #17
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Re: Solar Setup Adequate?

Re diodes - check your panel first - some have diodes in the connector box already and adding more would only drop voltage. Our panels (75W, 12V, one Neste, one Chinese copy) do not require extra diodes.

I think the choice of battery is largely up to how you use the stored energy. I would probably stick with plain, smaller batteries for daily use/charge systems. Bigger and deep cycle units will probably deliver their best in systems that are charged over longer periods, then discharged deeply, then charged again over a couple of days. In a daily cycle one can get better buck/value by simply getting a plain battery of say 110 Ah rather than a deep cycle one of, say, 90 Ah.

In any case, try to size the elements so that the batteries get fully charged, even if this does not happen in every cycle.

There are solar mounts that can be bought off shelf. With the right mast/pole, they allow you to tilt and rotate the panel.

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Old 18-10-2012, 06:58   #18
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Re: Solar Setup Adequate?

Quote:
Originally Posted by barnakiel View Post
Re diodes - check your panel first - some have diodes in the connector box already and adding more would only drop voltage. Our panels (75W, 12V, one Neste, one Chinese copy) do not require extra diodes.
All 12v solar panels have bypass diodes. These serve a different function to blocking diodes.
If you open your solar panel connection box and there are diodes fitted, don't assume they are blocking diodes. They are much more likely to be bypass diodes.
However,blocking diodes will do no good and only reduce power, if your solar controller disconnects the panels at night, (most of them). Even if your solar controller does not have this feature (or you have no controller) blocking diodes are of very marginal benefit for most panels.

Because blocking diodes reduced the rated output if the panel they are rarely fitted these days. Some instalations wll benefit from fitting a blocking diode, but most will be better leaving out any additional diodes.
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Old 18-10-2012, 07:32   #19
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Re: Solar Setup Adequate?

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Originally Posted by SunDevil View Post
I don't have a critical need for a lot of power, and it does cost 3-4x more, but Lithium batteries will last longer and take more abuse... I switched to one with that solar panel system above and it works fine.
However, they are substantially more than 4x the price of flooded lead acid batteries. If you don't have a critical need you are wasting dollars.



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Old 18-10-2012, 09:51   #20
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Re: Solar Setup Adequate?

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Originally Posted by noelex 77 View Post
All 12v solar panels have bypass diodes. These serve a different function to blocking diodes.
If you open your solar panel connection box and there are diodes fitted, don't assume they are blocking diodes. They are much more likely to be bypass diodes.
However,blocking diodes will do no good and only reduce power, if your solar controller disconnects the panels at night, (most of them). Even if your solar controller does not have this feature (or you have no controller) blocking diodes are of very marginal benefit for most panels.

Because blocking diodes reduced the rated output if the panel they are rarely fitted these days. Some instalations wll benefit from fitting a blocking diode, but most will be better leaving out any additional diodes.
Yep. There is probably more than one way the diodes were used (or not) by various manufacturers. I believe nearly all regulators today cut off at night but I am not sure if any diodes are necessary upstream from the regulator when more than one panel are connected to the regulator (?)


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Old 22-10-2012, 08:33   #21
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Re: Solar Setup Adequate?

Here's the thing, mono-crystalline panels seem to be slightly more expensive compared to their poly-crystalline comparative; but are they worth the price considering their better efficiency? If that's the case, perhaps home depot still has the best deal.

190watts for 315$, but does this mean that a MPPT controller is necessary for the around 36v's max its putting out?

ALSO - why is the amperage about the same for a 100watt and 190watt? - (5.4amps) Doesn't amps directly relate to amount of power being expressed? OR is it that you only need a larger watt panel if your trying to run higher voltage? - which in our case, is not necessarily.

Greatly appreciate all the input

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Old 22-10-2012, 08:57   #22
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Re: Solar Setup Adequate?

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Originally Posted by RoccoFreya View Post
Here's the thing, mono-crystalline panels seem to be slightly more expensive compared to their poly-crystalline comparative; but are they worth the price considering their better efficiency? If that's the case, perhaps home depot still has the best deal.

190watts for 315$, but does this mean that a MPPT controller is necessary for the around 36v's max its putting out?

ALSO - why is the amperage about the same for a 100watt and 190watt? - (5.4amps) Doesn't amps directly relate to amount of power being expressed? OR is it that you only need a larger watt panel if your trying to run higher voltage? - which in our case, is not necessarily.

Greatly appreciate all the input


Product Comparison Page
Solar panel effeciency is just related to size of the panel for the amount of watts.
So a more efficient 100w panel won't put out more power than less efficient 100w panel it will just be physically smaller.
There is considerable overlap in efficiency of mono and poly panels, so you have to sums to see how efficient the panels are. The 100w panel in the link is 0.64 sq meters which is reasonably good.

Yes an MPPT regulator is necessary with the larger panel because of the higher voltage of the panel. If a MPPT regulator is used with the 190w panel it will convert the extra voltage for current and the 190w panel will put more power into the batteries than the 100w panel.(roughly 1.9x as you would expect)

Another way of understanding it looks like both the 100w and the 190w panels use the same cells in their construction, but the 190w panel has more of these cells.
Each cell adds about 0.6v @ 5.4A as the cells are in series the voltage goes up, but the current stays the same. To feed the battery with more current we need to trade the volts or amps which needs a MPPT regulator.
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