Hi,
my photovoltaic system planning is likely going to end up at around 38 kWp (kilowatt-peak). The pitched roof will be fully covered on the south and north sides.
My main concern is that I was told (in the relevant forum) that the inverters get quite warm and that I shouldn’t install them in the utility room. We don’t have a basement, and our utility room is about 8.3 m² (90 sq ft). It will be a KfW 40 energy-efficient house. The garage is on the opposite side of the property and is planned to be built later, not directly connected to the house. A carport is planned directly adjacent to the utility room. Currently, I would probably try to install the inverters there. We will have two inverters because of the system size and string configuration. However, our house manufacturer uses a very light plaster, and the inverters are too heavy to mount directly on it. So I would need to mention this during the final selections and have wooden beams installed under the plaster, which would be expensive. Alternatively, I could somehow mount them on the carport itself, but I don’t want to significantly reduce the driveway width since it’s already quite narrow. I could also take the risk and install the inverters in the utility room after all. However, I have heard of cases where temperatures of 40°C (104°F) were reached there. Some people use fans to get rid of the heat. In our KfW 40 house, that probably wouldn’t even be allowed.
I can hardly find any information about this online. Some people report no problems even with 2 m² (22 sq ft) utility rooms; others have temperatures around 30°C (86°F). There is never information about the type of houses, and some posts are up to 10 years old. We are building a 103 m² (1,109 sq ft) bungalow for two people, with an Alpha Innotec Hybrox 5 (70 m² to 150 m²) air-to-water heat pump and a decentralized ventilation system.
Has anyone here had experience with inverter heat? How would you approach this issue? The battery storage obviously has to go in the utility room; it can’t be installed elsewhere.
my photovoltaic system planning is likely going to end up at around 38 kWp (kilowatt-peak). The pitched roof will be fully covered on the south and north sides.
My main concern is that I was told (in the relevant forum) that the inverters get quite warm and that I shouldn’t install them in the utility room. We don’t have a basement, and our utility room is about 8.3 m² (90 sq ft). It will be a KfW 40 energy-efficient house. The garage is on the opposite side of the property and is planned to be built later, not directly connected to the house. A carport is planned directly adjacent to the utility room. Currently, I would probably try to install the inverters there. We will have two inverters because of the system size and string configuration. However, our house manufacturer uses a very light plaster, and the inverters are too heavy to mount directly on it. So I would need to mention this during the final selections and have wooden beams installed under the plaster, which would be expensive. Alternatively, I could somehow mount them on the carport itself, but I don’t want to significantly reduce the driveway width since it’s already quite narrow. I could also take the risk and install the inverters in the utility room after all. However, I have heard of cases where temperatures of 40°C (104°F) were reached there. Some people use fans to get rid of the heat. In our KfW 40 house, that probably wouldn’t even be allowed.
I can hardly find any information about this online. Some people report no problems even with 2 m² (22 sq ft) utility rooms; others have temperatures around 30°C (86°F). There is never information about the type of houses, and some posts are up to 10 years old. We are building a 103 m² (1,109 sq ft) bungalow for two people, with an Alpha Innotec Hybrox 5 (70 m² to 150 m²) air-to-water heat pump and a decentralized ventilation system.
Has anyone here had experience with inverter heat? How would you approach this issue? The battery storage obviously has to go in the utility room; it can’t be installed elsewhere.
B
Bierwächter4 Jun 2025 18:35nordanney schrieb:
Why? Why not go directly for 25 kWh. It’s not much more expensive anyway if you’re doing everything yourself. So far, I haven’t really come across systems that large—usually up to a maximum of 11 kWh—so I never considered bigger storage. I was always assuming around €500–600 per kWh, and unfortunately, we have to watch our budget during the house construction.
I’ve also read that the battery should be cycled about 220 times a year to be worth it. In winter, it doesn’t get fully charged, and in summer, it’s not fully discharged, they say. So, I’d need to discharge it overnight. With my planned system size, it might be a bit different, although here only half of the system charges the battery with just one hybrid inverter. If the costs really aren’t that much higher, I might reconsider. However, space isn’t unlimited either.
M
MachsSelbst4 Jun 2025 20:52An electric car that consumes 20 kWh/100 km and drives 60–80 km per day would fit well into the system. If you also run the dryer, heat pump, washing machine, and dishwasher overnight via smart home control, it can make sense.
Provided this can be done at a reasonable price, without taking out a loan and with some DIY work.
If the solar specialist company handles the installation, a certified electrician connects everything, and Nordanney finances the project with a 6% consumer loan... then...
no.
Provided this can be done at a reasonable price, without taking out a loan and with some DIY work.
If the solar specialist company handles the installation, a certified electrician connects everything, and Nordanney finances the project with a 6% consumer loan... then...
no.
N
nordanney4 Jun 2025 23:23Bierwächter schrieb:
I have never really read about systems that large before, usually only up to about 11 kWh, so I never considered bigger storage. I was also assuming around $500–600 per kWh, and unfortunately, we have to watch our budget when building the house. Just to show what is possible...
That’s why I mentioned a large storage system. You shouldn’t spend more than 10k for 25 kWh.
Or as a low-voltage option (which is generally less preferred due to some disadvantages).
filosof schrieb:
I checked it today when the system was producing around 20kW. It was a bit warmer than just hand warm. The inverter is a SolarEdge SE25K-RW00IBNM4, operated with SolarEdge power optimizers (in case that’s relevant...).
According to the manufacturer, the efficiency is an "unique" 98.3%. I have the same model. When a cloud briefly passes by, you hardly notice any heat increase. But on sunny days when 25kW comes from the roof, it definitely gets quite warm. In my 15m² (161 sq ft) utility room, it gets pretty cozy. Because of that, I connected the exhaust of the mechanical ventilation system for indoor air quality directly above this room, so part of the warm air is "pumped out."
I’m not sure if it really helps much, but oh well, it makes me feel better. ;-)
Alex124 schrieb:
I have the same one. When a cloud passes by briefly, you don’t really notice much difference in terms of heat. But on sunny days, when 25 kW (27 hp) come from the roof, it definitely gets quite warm. So, in my 15 m² (160 ft²) equipment room, it does get cozy. That’s why I positioned the exhaust of the controlled residential ventilation system directly above this room, so some of the warm air is "pumped out."
No idea if it really makes much of a difference, but whatever—it gives me peace of mind. ;-) Today, 20-25 kW (21-27 hp) were present for a few hours. I placed a thermometer inside. It showed 22.5°C (72.5°F), about 1°C (2°F) warmer than the adjacent basement room without the inverter. Whether that’s really very cozy, I can’t really say.
T
Teimo19888 Jun 2025 12:06We have had a Kostal PIKO installed in the barn for 13 years. There have been no problems, but it is also installed completely protected from rain.
Then I have three SMA inverters in the attic. In summer, it gets extremely hot up there anyway, regardless of whether there are inverters or not. I would personally hang those outside as well. They probably have a few hundred watts of power loss. That definitely generates some heat.
Then I have three SMA inverters in the attic. In summer, it gets extremely hot up there anyway, regardless of whether there are inverters or not. I would personally hang those outside as well. They probably have a few hundred watts of power loss. That definitely generates some heat.
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