ᐅ Solar power system quote for our single-family home

Neubau2022 schrieb:

We want to build a carport and probably install photovoltaic panels there as well.

Plan everything beforehand. It’s easy to make mistakes that later make upgrades unnecessarily expensive.
(The best approach is, of course, to build everything at once from the start, but I understand that’s not always possible.)

Question for the experts (mainly Deliverer, but others are welcome too :p )

We are now planning to install modules on both roof sides (just as a reminder: 25° pitch, north / south).

Theoretically, 26 or 27 modules (depending on the position of the roof vents) fit on each side. The model is:

JinkoSolar solar module Tiger NE HC N-Type sw JKM410N-54HL4-B

Questions:

--> Should we really fill the north side completely with 27 modules? (I already have an idea what the answer might be)

--> One large inverter or two inverters, meaning one per roof side?

--> If two inverters, does the 70% limit apply to both combined or to each inverter separately?

--> Do I need to consider anything regarding snow guards? Should they be higher than normal so that snow does not simply slide over the modules and the guard into the garden?

Elias_dee schrieb:

--> Completely fill the north side with 27 modules? (I already suspect the answer)

Generally yes, ultimately it depends on the cost. An additional advantage with north/south orientation is that the strong midday peak on the south side doesn’t constantly trigger the 70% power limitation.

Elias_dee schrieb:

--> 1 large inverter or 2 inverters, meaning one per roof side?

Each roof side will be a separate string. So you only need one inverter with two inputs, which is almost always the case.

Elias_dee schrieb:

If 2 inverters, does the 70% limit apply to both together or each inverter separately?

The 70% limit always applies to the total generator capacity. The inverter ratings don’t affect the limit.

Elias_dee schrieb:

Do I need to consider anything regarding snow guards? Should they be higher than regular ones so that the snow doesn’t just slide over the panels and the guard into the garden?

My snow guards are simply installed with a bit of space below the lowest row of panels. The main issue is that the snow really stays on the panels until it completely melts. Sometimes I wish a bit of it would slide off and clear the photovoltaic area :p

Fuchur schrieb:

Each side of the roof will be a separate string. So, you only need one inverter with two inputs, which almost every inverter has.

I guess that won’t be enough. Definitely just one inverter, but 26 modules are probably too many for a current inverter in one string. So, it will likely be two strings of 13 modules connected in parallel to each input. Possible shading should be distributed evenly across all strings.
Since 27 is hard to split into two, you should either remove one (or better yet, add one more if there is space on the smallest roof area, or something like that ;-) ), making it again two times 13.

It’s best to avoid snow guards wherever possible. Shorten the vent pipes and build over them. Any carpenter can handle that.

Otherwise, as you suspected, the system will be fully packed. A 20 kWp system size is reasonable. Even in poor weather, you’ll get about 10% of the maximum output, roughly 2 kW. That’s usually enough for a bit of electric car charging and easily covers the heat pump including base load. Great!

Thanks to Fuchur and Deliverer! :-)

Regarding snow guards: I don’t want to leave them out. I currently live in a rented apartment with a garden, and in winter, snow and ice avalanches repeatedly crash heavily into the garden. This might not be life-threatening for us humans, but potentially dangerous for my two cats (who also go outside in winter) ;-)

--> However, snow guards don’t make sense if they are too low and the panels are installed right next to them. The attached photo was found in another forum, where the person wrote that the snow is not caught but simply slides over the panels, which of course should be avoided.

Regarding roof layout: in the second attachment, you can see the south-facing roof layout planned by the solar installer (which I also want to have exactly the same on the north side). The roof is completely full with 27 modules (it’s not a very large roof). Currently, there is no space for snow guards. The only solution—if I don’t want to omit an entire row of panels—might be to extend the roof overhang a bit... I still need to discuss this with the general contractor.

Thanks for the other tips regarding the inverter and strings!