Monocrystalline or polycrystalline?

[morasolar]

Can someone tell me if there is a difference between using monocrystalline and polycrystalline modules?
I am concerned in terms of their properties as far as power production in relation to clouds, to extreme heat, as well as longevity.
There seems to be a price difference, is this difference related to quality?

[zoneblue]

Once upon a time there was a useful distinction, these days the gap has closed. The polys have a slight cost afvantage, i beleive that efficiency is still in monos court. But i guess you know that effeciency is only an issue for those with space constraints. Dollars per watt is really all that counts.

[atop8918]

Agreed. Poly has a lower price-point but mono has the efficiency advantage. If you've got the space for them I'd go for the cheaper option and just buy more panels.

[morasolar]

Thanks for the info, is ok to mix monos with polys. The reason I ask is that I have 4, 255w Solarworld modules, that are no longer available. I will be using them in strings of three with a Midnite Classic 200, based on this, I will have to match them up with other similar modules to provide up to 4 strings to the Classic 200, this I believe in the max for this controller, based on the specs of these modules. Any other suggestions?
Thanks.

[Westbranch]

check the polarity. i f those panels. are Positive ground it may be tough to match...

[Vic]

SolarWorld PVs are very common,  so finding compatible SW PVs should not be difficult.

Generally,  when adding strings in parallel with existing strings,  you will want the Vmps to be within 5% of what you now have.   10% Vmp variation would be the upper limit of Vmp variation.

If you were mixing existing PVs in series with new PVs,  the Imp of the new panels ideally should be within 5% Imp of the existing PVs within a string.   10% would be the upper limit of the Imp variation in a string.   This is the "standard" wisdom.

There are not many PVs that need Positive ground.  SolarWorld modules (that I have used/seen)  are NOT Positive ground PVs.

Mono PVs seem to have a slightly higher Vmp for a given power level,  vs Poly modules.

And,  as has been stated,  Monos are slightly more efficient,  so usually require a somewhat smaller area for the same output  power.

FWIW,  YMMV,   Vic

[morasolar]

Great, thanks.