We received a quote from the electrician for a 10 kWp photovoltaic system. However, I am wondering whether investing in a 10 kWp system is really cost-effective or if a smaller system might be sufficient. Our four-person household consumes around 4,500 kWh in our rented apartment without a heat pump. In our planned single-family house (140 m² (1,507 sq ft), KfW 55 standard), there will be an air-to-water heat pump and possibly an electric car in the future. I am not familiar with the energy consumption of heat pumps, but wouldn’t 8 kWp or even less be enough? We do not want to feed electricity back to the grid, and the feed-in tariff is not a reason for us to choose a larger system.
Tolentino schrieb:
Ok, that makes sense, but how much does an inverter cost? Besides the extra space in the utility room, which I might not have...Is there perhaps a misunderstanding where you think you can do without the inverter by using power optimizers!? Unfortunately, that’s not the case and you have misunderstood something 🙁
Edit: ah, obviously I misunderstood you and you mean "an additional/second" inverter.... Sorry.
D
Deliverer2 Feb 2022 11:35Four roof surfaces on one inverter are generally not a problem. You just need two sides with the same number of modules.
Optimizers are only necessary if, for example, you want to include a dormer with two by two modules each oriented differently, or if there are four roof surfaces, two of which are heavily (and differently) shaded.
Use optimizers only as a last resort. They double the number of plug connections and introduce numerous electronic components that are exposed to moisture and extreme temperature fluctuations.
When these devices were developed, this might have been a good idea, as there were hardly any inverters with shade management at that time. Nowadays, however, this is standard, and every inverter can handle shading without any issues.
Optimizers are only necessary if, for example, you want to include a dormer with two by two modules each oriented differently, or if there are four roof surfaces, two of which are heavily (and differently) shaded.
Use optimizers only as a last resort. They double the number of plug connections and introduce numerous electronic components that are exposed to moisture and extreme temperature fluctuations.
When these devices were developed, this might have been a good idea, as there were hardly any inverters with shade management at that time. Nowadays, however, this is standard, and every inverter can handle shading without any issues.
Always consider each case individually... with around 35 modules (13kWp) at 60-80€ per module (installed), it might be worth thinking about a second or two smaller inverters 😉
For a roof with panels on all four sides, this can definitely make sense "with or without" a second inverter and optimizers, since different roof sides can be connected in one string. The reason for a second inverter is usually that each side gets its own MPP tracker, and most inverters have only 2, while the larger ones have 3.
For a roof with panels on all four sides, this can definitely make sense "with or without" a second inverter and optimizers, since different roof sides can be connected in one string. The reason for a second inverter is usually that each side gets its own MPP tracker, and most inverters have only 2, while the larger ones have 3.
Ok, I don’t know much about this, but I take it that the solar installer wasn’t completely off base.
I’m planning to install 48 panels (about 18 kWp) on four roof sides (two long, two short), and he said that using SolarEdge would be quite practical, otherwise I would need a second inverter.
He also mentioned that with a battery storage system, I would need a second inverter if all four sides are fully utilized. That’s why he only offered me full use without storage, or installation on three sides with storage.
I’m planning to install 48 panels (about 18 kWp) on four roof sides (two long, two short), and he said that using SolarEdge would be quite practical, otherwise I would need a second inverter.
He also mentioned that with a battery storage system, I would need a second inverter if all four sides are fully utilized. That’s why he only offered me full use without storage, or installation on three sides with storage.
No, there have been much different ones 😀 It will work.
Do you have significant shading? With shading, you can install these systems; without it, it usually isn’t cost-effective (minimum 2,500-3,000€).
I would install on all four sides, with two inverters for the opposite sides so that they can even be slightly smaller than the rated capacity (the sun shines more on one side, the north side gets less).
For example:
1 inverter for north-south with 8-10kW, one string per roof side
1 inverter for east-west with 6-8kW, one string per roof side
One of the two inverters could be a hybrid to also manage the battery storage.
I’m not familiar with the pricing or product range of SolarEdge inverters, but for Huawei, the 10kW model would probably be 300-500€ cheaper than the 18kW, and the 8kW would be around 1,500€ less; in return, you save about 3,000€ due to no optimizers, and small items like cables, DC isolator, fuses, etc., would of course still add up (estimated under 1,000€).
The last issue that could complicate things would be too short string lengths on the shorter sides, but that is manageable.
Do you have significant shading? With shading, you can install these systems; without it, it usually isn’t cost-effective (minimum 2,500-3,000€).
I would install on all four sides, with two inverters for the opposite sides so that they can even be slightly smaller than the rated capacity (the sun shines more on one side, the north side gets less).
For example:
1 inverter for north-south with 8-10kW, one string per roof side
1 inverter for east-west with 6-8kW, one string per roof side
One of the two inverters could be a hybrid to also manage the battery storage.
I’m not familiar with the pricing or product range of SolarEdge inverters, but for Huawei, the 10kW model would probably be 300-500€ cheaper than the 18kW, and the 8kW would be around 1,500€ less; in return, you save about 3,000€ due to no optimizers, and small items like cables, DC isolator, fuses, etc., would of course still add up (estimated under 1,000€).
The last issue that could complicate things would be too short string lengths on the shorter sides, but that is manageable.
D
Deliverer2 Feb 2022 12:16I can agree to almost everything except this part:
is really only necessary if the roof sides are significantly different. If you find two roof sides with the same number of modules, you connect them in parallel. Usually, this means north and south are connected in parallel to one MPPT, and east and west the same. Depending slightly on the roof pitch, a 15 kW inverter should be sufficient for 18 kWp. This setup would be streamlined, less prone to errors, and efficient.
borxx schrieb:
2 inverters for the opposite sides,
is really only necessary if the roof sides are significantly different. If you find two roof sides with the same number of modules, you connect them in parallel. Usually, this means north and south are connected in parallel to one MPPT, and east and west the same. Depending slightly on the roof pitch, a 15 kW inverter should be sufficient for 18 kWp. This setup would be streamlined, less prone to errors, and efficient.
Similar topics