......please help me with my confusion

[Sunking]

Thanks again... I see where you are coming from. I've just got off the phone with the supplier, and raised this concern with him. Hi reply was that allowing for inefficiencies, the panels will never put out the spec'd output.

Well he is correct, but not telling you everything. Could be he does not know.

Panels are current sources, not voltage like a battery. What varies is the CURRENT and it is directly proportional to the amount of Sun Lite striking its surface. So when you see in the SPEC Imp is a lab condition, not real world. In real world current will be lower, thus less power than specified. However open circuit voltage (Voc) is not affected by solar insolation. It is affected by temperature. It is a negative coefficient meaning as temps drops voltage goes up. When you look at a panel spec Voc is stated at 25 degrees C. There is also another spec called Temperature Coefficients that is used by designers to calculate Voc voltage as the temp drops. They use worse case cold numbers for your area. I am pretty sure your temps go below 25 C.

Since you are in a warm climate here is a simple formula to use. Voc x 1.25 = Corrected temp Voc. So if your CC Voc rating is 150 volts, then you know you want to keep Voc to 150/1.25 = 117 volts. So look at your panels specs, find Voc and add them up in series to see if you stay below 117 volts. I suspect thos panels Voc are greater than 117/4 = 29.3 volts. I bet they are pushing 40 volt Voc.

[Bala]

Well he is correct, but not telling you everything. Could be he does not know.

Panels are current sources, not voltage like a battery. What varies is the CURRENT and it is directly proportional to the amount of Sun Lite striking its surface. So when you see in the SPEC Imp is a lab condition, not real world. In real world current will be lower, thus less power than specified. However open circuit voltage (Voc) is not affected by solar insolation. It is affected by temperature. It is a negative coefficient meaning as temps drops voltage goes up. When you look at a panel spec Voc is stated at 25 degrees C. There is also another spec called Temperature Coefficients that is used by designers to calculate Voc voltage as the temp drops. They use worse case cold numbers for your area. I am pretty sure your temps go below 25 C.

Since you are in a warm climate

here is a simple formula to use. Voc x 1.25 = Corrected temp Voc. So if your CC Voc rating is 150 volts, then you know you want to keep Voc to 150/1.25 = 117 volts. So look at your panels specs, find Voc and add them up in series to see if you stay below 117 volts. I suspect thos panels Voc are greater than 117/4 = 29.3 volts. I bet they are pushing 40 volt Voc.

NZ would not really be what I call a warm climate, Fist time I was on the South island it snowed in January, which is the hottest part of the year. It still has a few glaciers. Depends where the OP is.

[Sunking]

NZ would not really be what I call a warm climate, Fist time I was on the South island it snowed in January, which is the hottest part of the year. It still has a few glaciers. Depends where the OP is.

Even the more reason to go 2 x 2

[j.steele]

Even the more reason to go 2 x 2

Well he is correct, but not telling you everything. Could be he does not know.

Panels are current sources, not voltage like a battery. What varies is the CURRENT and it is directly proportional to the amount of Sun Lite striking its surface. So when you see in the SPEC Imp is a lab condition, not real world. In real world current will be lower, thus less power than specified. However open circuit voltage (Voc) is not affected by solar insolation. It is affected by temperature. It is a negative coefficient meaning as temps drops voltage goes up. When you look at a panel spec Voc is stated at 25 degrees C. There is also another spec called Temperature Coefficients that is used by designers to calculate Voc voltage as the temp drops. They use worse case cold numbers for your area. I am pretty sure your temps go below 25 C.

Since you are in a warm climate here is a simple formula to use. Voc x 1.25 = Corrected temp Voc. So if your CC Voc rating is 150 volts, then you know you want to keep Voc to 150/1.25 = 117 volts. So look at your panels specs, find Voc and add them up in series to see if you stay below 117 volts. I suspect thos panels Voc are greater than 117/4 = 29.3 volts. I bet they are pushing 40 volt Voc.

Well put sunking..... although it's taken a few reads to enable me to get my head around it. Looks like it's 2x2 then! Thanks

As for the batteries, I will taiho on those for a while, as it's the dead of winter here and the cabin will not be operational before summer, so I figure no point having the batteries sitting around in the cold not being used. Plus it'll give me time to properly insulate (polystyrene) and ventilate my shed.(probably use computer fans for this) I am learning a lot about battery care as I go along, and I can see that there must be some very expensive mistakes made through lack of care/maintenance. Thanks for the help guys, I am keen to pick your brains about refrigeration, but will start another thread.

[j.steele]

NZ would not really be what I call a warm climate, Fist time I was on the South island it snowed in January, which is the hottest part of the year. It still has a few glaciers. Depends where the OP is.

I hail from the Eastern Bay, the sunshine capital of NZ, 2792 hours of the stuff per year, no snow, and usually no more than 3 or 4 heavy frosts! Tis a no brainer to try to harness this resource. We have a very basic solar hotwater setup that works even in winter. I am hoping once I get my head around the PV stuff( if ever) for our cabin, I am keen to invest in a grid tied sytem on our main house.

[Bala]

I hail from the Eastern Bay, the sunshine capital of NZ, 2792 hours of the stuff per year, no snow, and usually no more than 3 or 4 heavy frosts! Tis a no brainer to try to harness this resource. We have a very basic solar hotwater setup that works even in winter. I am hoping once I get my head around the PV stuff( if ever) for our cabin, I am keen to invest in a grid tied sytem on our main house.

Ok, i have caved and kayaked on the south Island, have only had airport stop overs on the North island.

[Streetsweaper]

How do I use a 12v timer for my led lights . Where do I connect it from ?