Living offgrid with small solar system(s)

[Muhendis]

The diodes on the back of the panel are bypass diodes which are there to provide a current path in the event of the panel becoming faulty when wired in series with others. These are the ones in the sealed box on the back of the panel. When the panels are connected in parallel then each panel needs to have a blocking diode to prevent current from a higher output panel trying to flow into a panel with a lower output. This can happen if one panel is shielded from the sun and the other is not. If there was no blocking diode, the voltage of the exposed panel will then appear at the terminals of the shielded panel with catastrophic results.

This may help to understand the functions of the diodes about which you are asking.

http://www.electronics-tutorials.ws/diode/bypass-diodes.html

The blocking diodes for my system are, rightly or wrongly, mounted in the combiner box together with the fuses for each group of panels and a DC isolator for each group plus lightning arrestors.

[Jing Joe]

The diodes on the back of the panel are bypass diodes which are there to provide a current path in the event of the panel becoming faulty when wired in series with others. These are the ones in the sealed box on the back of the panel. When the panels are connected in parallel then each panel needs to have a blocking diode to prevent current from a higher output panel trying to flow into a panel with a lower output. This can happen if one panel is shielded from the sun and the other is not. If there was no blocking diode, the voltage of the exposed panel will then appear at the terminals of the shielded panel with catastrophic results.

This may help to understand the functions of the diodes about which you are asking.

http://www.electronics-tutorials.ws/diode/bypass-diodes.html

The blocking diodes for my system are, rightly or wrongly, mounted in the combiner box together with the fuses for each group of panels and a DC isolator for each group plus lightning arrestors.

YUP. M is spot on. BUT You could have all the diodes down below only IF you ran a positive wire from each panel down too. One common black negative would suffice. But why contemplate this? It would be a different answer again if you had anything other than the 12V system we know you have.

George; I don't think you mentioned your purpose in your question? Diodes are (usually) as M says in the sealed box on each panel. Why change this?

[Jing Joe]

Question:

If i connect panels parallel can i put the diode of each panel inside the house before the fusebox?? I always see examples whereby the diode is placed behind the panel (in the waterproof connector box).

Looking at your Q closer;- Again George, the diode of each panel could only near the fuse-box (and be of any use) IF a separate wire was run from each panel.

Trying to imagine why, and even if you were contemplating charging two separate batteries,?? you would have just two feeds coming down, but the diode/s would still be up top in the panel/s.

M's advice is best.

[George Harmony]

Ok...thanks for all the answers above.

George; I don't think you mentioned your purpose in your question? Diodes are (usually) as M says in the sealed box on each panel. Why change this?

I recently bought some panels and there are no diodes (pre)installed.

The first panel i bought months ago was a diode preintalled.

Why solar systems need diodes that i understand. Im just wondering why the diodes must be on top of the solar-chain. If the wires of each individual panel goes in to my control center inside my house i am able to measure each individual panel inside. If this is the case i thought why not connect the diode inside.

[Crossy]

Ok...thanks for all the answers above.

George; I don't think you mentioned your purpose in your question? Diodes are (usually) as M says in the sealed box on each panel. Why change this?

I recently bought some panels and there are no diodes (pre)installed.

The first panel i bought months ago was a diode preintalled.

Why solar systems need diodes that i understand. Im just wondering why the diodes must be on top of the solar-chain. If the wires of each individual panel goes in to my control center inside my house i am able to measure each individual panel inside. If this is the case i thought why not connect the diode inside.

If you are bringing the individual panel connections down then putting the diodes at the non-panel end is fine. In the normal arrangement of several panels in series the bypass diodes are at the panel because that's the easiest way to wire it.

[Muhendis]

Pros and cons of where to place the bypass diodes.

If they are in the box on the back of the panel then it's a case of fit and forget.

If they are in the junction box in the house then when you wish to expand/change your system to wire the panels in series you will need to move the bypass diodes again unless of course you have buckets full of money and have two wires for each additional panel.

I don't know how you feel about this but I am the sort of person who would only wish to do that once (I'm lazy). As Crossy says it is far easier to wire the panels together locally and future accessibility could also be a challenge.

[George Harmony]

Once again,thanks for the answers,remarks and tips. It has no negative consequences to put the diode(s) at the end.

Its indeed more work and ofcoure more costs...pffff perhaps not wise to lead the wires of each panel inside.

[Jing Joe]

Ok...thanks for all the answers above.

George; I don't think you mentioned your purpose in your question? Diodes are (usually) as M says in the sealed box on each panel. Why change this?

I recently bought some panels and there are no diodes (pre)installed.

The first panel i bought months ago was a diode preintalled.

Why solar systems need diodes that i understand. Im just wondering why the diodes must be on top of the solar-chain. If the wires of each individual panel goes in to my control center inside my house i am able to measure each individual panel inside. If this is the case i thought why not connect the diode inside.

Ah Ha George now that makes more sense than at first. You will only need One Black (thicker) common wire and one positive red for each panel (knowing that you have 12v system). The individual red wires need not be as thick as in a parallel plan, so that's a plus. You would always have the option to easily single out one/some panels for a second battery stream.

No matter how long is the run (almost) it could be a good long term investment because :- Panels deteriorate and should be covered by warranty of so much % power drop over so many years. A friend has had a couple of panels fail after 6 months.

If some existing panes have diodes; leave them there? no real challenge except they will appear to be 0.6 to 1.0 volts lower than others but you wont really notice this in the O/C approximate 17V nominal.

You could relocate them from up-top to down-below. If not just be sure of the wire identification of those panels. The haves and the have-nots again.

Just use a dummy link in the suggestion below.

Dust is misleading and partly involves panels angles versus rain as I've mentioned before BUT to be able to monitor any of this as you said does make sense George.

Its a once only investment in a bit more copper and i wish I had done it to mine because ;-

Sixteen years ago the new panes gave 34A at battery voltage 54V. Now days it is about 24A, but then could be due for a clean despite recent good rains. It usually gets better but has never been the same as new.

Being able to monitor with a M/M straight across each of your panels on 10A scale and then the 20V scale would be very handy records.

You could neatly/simply use a terminal strip with a pair of adjacent terminals for each diode. Just release one end of the diode to M/M access the current contribution of each panel -- as a third test to the above. And even the above A and V tests would be simpler to do.

I wouldn't have done your suggestion because the distribution. Mine is just two feeds i.e 12 groups of panels in parallel twice. Each group is 4 x 12V.

It would have needed 24 separate red pos wires and 24 black neg wires. I would have left the existing diodes up-top.

The best I can hope for using your monitoring principle (as mine exists now) would only determine if one group or the other was down. Then get on the roof and open each junction box on each panel.

This seems too much trouble so again;- good on ya George, no ideas in brainstorming should ever be ridiculed and whoever speaks derogatorily, does so against themselves instead of the contributor -- for all to see.

Edited March 30, 2016 by Jing Joe

[George Harmony]

The individual red wires need not be as thick as in a parallel plan, so that's a plus. You would always have the option to easily single out one/some panels for a second battery stream.

No matter how long is the run (almost) it could be a good long term investment

Thank you very much for your remarks and tips. If its a good investment for the long term i will (re)consider

[KonaRain]

Diodes might be for lightning strikes.

Brass Solar water panels are 90 percent a water sandwich.(90%+ wet)

Very efficient for water heating!

A SOLAR water tank loses 3° c in 24 HRS.

Aloha

Edited April 5, 2016 by KonaRain

[George Harmony]

Attached pict i downloaded from somewhere on internet. Lets say i make an outside wall like this and make it constantly wet, like a waterfall. Will it help to cool the room inside (a little bit)?

[splitlid]

Maybe. A little,and that is a real little. But doing so would be more trouble than it's worth. Keeping it clean would be huge issue. And then waterproofing.

Keeping the sun off the walls would work best.

[Muhendis]

Splitlid is spot on with regard to the problems outweighing the benefits. A good way to shield the walls from direct sunlight would be to plant a few trees for shading being careful of course, to keep the shade away from your solar panels Having a cavity wall makes a big difference so I wonder if batten mounted dry liner on the interior walls might help. It would create the cavity although it would not be as good as the cavity wall. You could do that to the walls of the rooms that are the biggest problem.

[George Harmony]

One outside wall is not painted yet. I thought i make like one of these.

@splitlid gave some tips. Perhaps i combine this with also a canopy.

[Crossy]

Those wet walls ^^^ are really intended as a feature rather than of any practical use.

Shade is the real answer, either with vegetation or, if not the space or inclination, a shade panel. Sort of like a flying roof on its side.

[George Harmony]

Yes @crossy. I now understand. I had already plans to make such "wet wall" and was wondering if it will help to cool the space inside. Now i will make a sort of a canopy also.

When its ready i will post some picts. For the canopy to shield the wall we will start tomorrow. Its only a 5m long wall, 3.30m high.

Thanks for all tips.

[Jing Joe]

Attached pict i downloaded from somewhere on internet. Lets say i make an outside wall like this and make it constantly wet, like a waterfall. Will it help to cool the room inside (a little bit)?

Hi George again; Evaporation for cooling usually only works in drier climates.

Don't know the exact humidity percentage or temperature considerations but the nearest example is our own bodies attempts to cool.

When our humidity here in this part of Aus. is down to 30% and cool or a bit warm, it is easy to become dehydrated when you are not obviously sweating.

Conversely, such as where you are, nearby Jakarta has 26degrees and 100% humidity TODAY and you would be sweating

profusely in an attempt to cool your skin.

I'm sure a wet wall would be useless today and possibly even when the humidity might be down to 80%, so how does today compare with other seasons there before you waste time and money on such a project?

Cheers mate.

Edited April 14, 2016 by Jing Joe

[Jing Joe]

Diodes might be for lightning strikes.

Brass Solar water panels are 90 percent a water sandwich.(90%+ wet)

Very efficient for water heating!

A SOLAR water tank loses 3° c in 24 HRS.

Aloha

Aloha KonaRain, The diodes probably would not stand a chance (totally fried) in a direct lightning strike and might just reduce some nearby strike but without going into the details of the polarity of such a surge, here is the main reason;-.

They are for protecting against power going backwards into panels from several

situations and is well and truly covered in previous posts, many pages back.

This has been a most comprehensive coverage of small solar set-ups if you are contemplating such.

Edited April 14, 2016 by Jing Joe

[Jing Joe]

Yes @crossy. I now understand. I had already plans to make such "wet wall" and was wondering if it will help to cool the space inside. Now i will make a sort of a canopy also.

When its ready i will post some picts. For the canopy to shield the wall we will start tomorrow. Its only a 5m long wall, 3.30m high.

Thanks for all tips.

Some folks make a simple evaporation system with a fine soaker hose spraying on to a hanging sheet of vege garden type U.V. shade cloth (probably the lowest % sun reduction cheapest grade)and letting any prevailing wind do the evaporation. You should experiment with this before the work and expense of building a wall that can fall over especially if its solid, and excess water in the foundations. Kids have been killed here from 2.5M solid walls..

.

Soaker hose for the lawn is typically a semi clear green PVC roll-up hose with thousands of pin holes along it. You could make/experiment your own with thin walled 1/2 inch black poly pipe and making many pin holes. e.g. drive many pins through a 300mm length of pipe as a tool to mass produce the many holes needed. Tap them into the main pipe , remove as a group and move on along the pipe.

Edited April 14, 2016 by Jing Joe

[George Harmony]

Thanks for your reply jingoe.

As decoration only i plan to make such wall with natural tiles. Ive seen many houses whereby they have to repaint each year (maintanence). I thought i fill it like above picts and circulate water and a small fishpond underneath with for example goldfishes

Perhaps with such walls you have less maintanence.

Edited April 15, 2016 by George Harmony

[Muhendis]

I have also seen these not too far from where I live. They are very relaxing to look at and a very nice feature. I'm sure yours will be no exception Ge@rge.

[Naam]

Thanks for your reply jingoe.

As decoration only i plan to make such wall with natural tiles. Ive seen many houses whereby they have to repaint each year (maintanence). I thought i fill it like above picts and circulate water and a small fishpond underneath with for example goldfishes

Perhaps with such walls you have less maintanence.

and the pump to circulate the water will be powered by 600 volts generated by an Electrophorus electricus?

Electric eels can generate an electrical charge of up to 600 volts in order to stun prey and keep predators at bay.

http://animals.nationalgeographic.com/animals/fish/electric-eel/

[Muhendis]

Don't be silly N@@m.

George will be sitting next to it pedaling away on his bicycle generator whilst enjoying a beer or two.

You know what these dutch are like about bikes.

Edited April 15, 2016 by Muhendis

[Naam]

Don't be silly N@@m.

George will be sitting next to it pedaling away on his bicycle generator whilst enjoying a beer or two.

You know what these dutch are like about bikes.

or perhaps he uses his electric drill to power the pump?

[George Harmony]

This submersible pump 12 volt and i do not need a ups for this cause it runs during the day totally free powered by the sun and in the evening it will draw a little bit from my battery. Btw, this pump can also be used as a well pump

Edited April 15, 2016 by George Harmony

[George Harmony]

And brushless for 24 hours operation also for my planned hydroponics

[George Harmony]

Talking about pumps @naam,

Plan also to make a swimming pool. Just saw this on internet which i like very much.

Im wondering what kind of pump i need to operate such a relatively small pool solar powered.

Edited April 15, 2016 by George Harmony

[Naam]

that relatively small pool is much bigger then my pool George and requires in my [not so] humble opinion a 1½hp (~1kWh) pump.

[KonaRain]

Thanks..I thought the bushes sounded goid for cooling. Hang some plastic or tarps for a few years until the plants grow. Gotta be right sized plants..we have potacarpas that grow too tall to shade dat window.

Hawaii is same latitude as LoS, so online there must be plenty stuff about landscape shading.

Nice stand alone pool, Naam

[KonaRain]

Solar panels are getting to $1 per watt and under. PV.

US made guaranteed panels. China, even cheaper. The Road Trek Eco Tek RV guys have the Li-Ion battery system like the Tesla guy, for about $3000 with hundreds of amp hours available.

I live offgrid with just a generator, so I'm looking into these battery systems, so stay tuned..

More later..

Alohz