a few questions regarding panel changes

Re: a few questions regarding panel changes

It won't be perfect--But you should get a DMM with a 10 amp (or whatever is the maximum current of your panels) and measure the Isc (short circuit current). That and measuring Voc (voltage open circuit) will find most of the bad panels.

To find the rest of the "bad panels"--if they are Vmp~15-17 volts, you can attach them temporarily to your car battery (watch polarity--you can instantly ruin your panels if wired backwards) and measure ~Imp (there are a few types of failures where Voc and Isc look good, but the panels still don't work correctly).

For an array with more than two parallel connected strings--I would use a fuse/breaker that is around 2x Isc or Imp... You will not get false trips and you should not get too much current and reduce the chance of a fire (from overheated panels/wiring in the case of a short).

If you have only one or two parallel strings behind a solar charge controller, you don't really need a series protection fuse per string.

-Bill

Re: a few questions regarding panel changes

I am not sure I understand you 100%--But you only need one fuse/breaker per series string (say you have two "6 volt panels" in series--that is one "12 volt string). With a mix of panels, the fusing/breaker setup does get to be a bit of mess. With larger arrays, the protective fusing/breakers is important if there is a short or broken panel. The other panels can back-feed the short and over heat the wiring or cause an arc which can light-off debris in the area.

For paralleling panels--ideally the Vmp of each string should be around 17-18 volts (at STC).

Depending on the controller type PWM--cheaper type--You can parallel panels just fine as long as the Vmp is >~15-16 volts. If you have panels with Vmp over ~21-24+ volts--then you should look at a MPPT type charge controller for those "higher voltage" Panels. With large voltage miss-matches (for parallel connections), you can loose quite a bit of energy.

For MPPT type charge controllers, the Vmp of each string should match all of the others within ~10%.

For series connections of panels, their rated Imp current should be within ~10%.

I am not sure about the drain holes for the frame--If you are talking about on the top near the glass--Be very careful, those are typically made from tempered glass an any nicks or pressure (and heat) at the edge of tempered glass can cause the whole pane to shatter (instant useless panel).

I personally, would not drill/work around the edge of the panels attempting to drill / file / cut drain areas. I think you are left with soap and bleach to keep the moss down.

You can try small zinc or copper strips (stripped copper house wiring?) silicon glued to the top edge of the glass (let the metal ion containing rain water wash down the face of the panels)--out of the way of the solar cells--I have not tried it, but zinc and copper is supposed to be a decent biocide for moss growing on roofs--perhaps it would work here--attach the zinc/copper directly to the glass--you don't want to risk corrosion if there is an electrical connection to the aluminum frame.

Don't know if it would work--but might be worth a shot on a couple panels and see what happens.

-Bill

Re: a few questions regarding panel changes

deepspace wrote: »

The controller here is a Trace c60 (I know trace is no longer but the same controller is available under new name).

They are now Xantrex/Schneider Electric... But from what I understand, still pretty much the same product shipping today.

So the query is would I gain anything by changing out the bayonet type fuse in the disconnect opting for a breaker? Since I have all this torn apart.

If the fuse is protected from the weather and not causing you any issues--There is no pressing reason to use circuit breakers instead. Some people like the ability to turn off panels/strings using the circuit breaker like a switch to work on system, check the output of each string, etc...

As always, having a couple spare fuses (or even circuit breakers) on hand is always a good idea. Fuses and Breakers tend to be the most unreliable parts of an electrical circuit (by design).

Really a personal choice vs costs.

One other question I have a DR series (1512) inverter which the transfer switch fuse appears bad I have not been able to find a replacement. Not a diy project?

It can be very difficult to find parts for any electronics that are over 10 years old--most vendors have dropped support/repair services for such devices, and the independent repair shops also are limited to old spares and cannibalizing used equipment.

Although--fuses are usually pretty much the same decade after decade. Perhaps you can post the name/part number of the fuse or a photograph of it...

-Bill