Currently I have 2 strings of Risen 325W panels. These are not made anymore. In the overcast weather we've had lately the system has struggled and could not charge the battery. On sunny days it will be charged usually by 11.

So I thought I might upgrade the north facing string so I have a bit more woema.

I looked at Canadian 550. I did the numbers. The inverter will accept 6 of those in series (just like the current string). But questions arise.

The Risen are polycrystalline, the Canadian are mono. Is this significant?

My east facing string wakes up early in the morning as the rising sun hits them, but the North string turns on (125V for my inverter) quite early. Conversely at 14:00 the east facing string is still producing 25 to 30% of the power, even though the sun is striking them from the side and at a shallow angle. Is this a property I can expect from all brands of panels? I have no idea if this is exceptional or not.

Other than that it looks OK. The proposed replacements are a little bigger, but I have room. An extra 30kg doesn't worry me. I'm assuming the existing wiring can be retained.

Oh... The protection. I'm attaching a shot of the DC board to show what is in place for each string. Can these be retained?

2 minutes ago, Bobster. said:

Currently I have 2 strings of Risen 325W panels. These are not made anymore. In the overcast weather we've had lately the system has struggled and could not charge the battery. On sunny days it will be charged usually by 11.

So I thought I might upgrade the north facing string so I have a bit more woema.

I looked at Canadian 550. I did the numbers. The inverter will accept 6 of those in series (just like the current string). But questions arise.

The Risen are polycrystalline, the Canadian are mono. Is this significant?

My east facing string wakes up early in the morning as the rising sun hits them, but the North string turns on (125V for my inverter) quite early. Conversely at 14:00 the east facing string is still producing 25 to 30% of the power, even though the sun is striking them from the side and at a shallow angle. Is this a property I can expect from all brands of panels? I have no idea if this is exceptional or not.

Other than that it looks OK. The proposed replacements are a little bigger, but I have room. An extra 30kg doesn't worry me. I'm assuming the existing wiring can be retained.

Oh... The protection. I'm attaching a shot of the DC board to show what is in place for each string. Can these be retained?

You can leave all the protection as is. If the fuses are a tad too low you can go up to 32A which should be fine.

There is a market for your size panels. On a regular basis I see guys looking for such panels to match their old system.

No need to worry about mono vs poly. If a panel is rated at 400W for either that is the output. During certain conditions the theory is that mono do produce more power. It could be so but of theoretical importance for a system working 364 days a year.

I have both and different makes and they all perform the same relative to the rating plate.