Energy Matters Forums

[Newt]

Back again. I am in the process of placing 8 of the 190W panels on my eastern roof. Today I mounted the racking and 4 panels in one string, tomorrow I hope to add the other 4. It seemed like a relatively straight forward process.

Questions:

What box do I need to run the two strings into? Is it mounted on the roof, or should I put it under the eaves? A junction box came with the used equipment, it has 2 circuit breakers, one for each pole - I guess it was a single string array as it was grid connect. Can I add 2 more circuit breakers and then combine them in the box before sending to the MPPT controller? The cables supplied are 4mm, but the connectors don't match the panel connections. Are diodes needed anywhere in this set up?

Any advice would be appreciated.

Cheers

[Newt]

Some images showing panel connectors which say C4. Inside junction box with two fused circuit breakers. Array isolator.

[Newt]

I now have the East panels all connected and am pleased with the harvest. Even at 4pm yesterday in cloudy conditions the panels were producing 400 W which quite surprised me, they continue to produce power well after midday and begin when the sun gets up. About 4.7kW by midday in partial cloud today. At about 1130AM today in 37C heat, the panels were producing approx 1368 W, which is about 90% of max....too hot for max of course.

Wasn't too difficult a job....I got advice from local solar installers about wiring, fuses etc, things I wasn't too sure about.

Question: Do I need to place the racking earth cable attached to the side of the house in conduit?

Cheers

[Gordon-Loomberah]

Question: Do I need to place the racking earth cable attached to the side of the house in conduit?

The PVC will deteriorate in the sun, then the Copper will corrode when it gets wet, so yes, it would be a good idea to protect it in conduit.

[Newt]

Thanks for that. Another question. Do all the roof panel cables need to be in conduit? The backs of the panels do not have a conduit suited (ready) connection as the BP ones on my ground array have. If so, I'm wondering how this is done.

The system is working well....running AC from about midday to around 6pm still charges the batteries (8 x 12v AGM) to float. At the moment I rarely drop below 10pc DOD.

Thanks for any advice.

Cheers
Mark

[Gordon-Loomberah]

I think they generally just need to be bundled up and tied in place out of the way and out of the sun. If they have free air circulation around them they will stay cooler than if touching hot metal, panel or roof.
However, I'm not a CEC certified installer, so don't know what the regulations are

[Warpspeed]

My system runs the solar panels up at around 200 to 280 dc volts, and the metal roof gets VERY hot, and PVC wiring will definitely soften at high temperatures. So for safety reasons some extra insulation up there on the roof may not be such a bad idea.

If its a 48v system or less, its much less likely to electrocute you.
But for only a very few dollars, plastic conduit is very good value IMHO.

[davidg]

I think they generally just need to be bundled up and tied in place out of the way and out of the sun. If they have free air circulation around them they will stay cooler than if touching hot metal, panel or roof.

Stainless Steel Cable ties or Solar Clips to something that supports the cables, ie array rails or the frame of the panel, cable not allowed to be "left hanging" around.