ᐅ Photovoltaic System: How Many kWp Are Sufficient for a House?
Created on: 19 Mar 2020 09:10
L
lin0r87
Hello everyone!
We are building a semi-detached house and want to install a photovoltaic system on the roof. The orientation would be south/west and north/east. We intend to use most of the electricity ourselves. A battery is not planned, as the cost is quite high for such a system and it probably doesn’t make financial sense.
We have received an offer that includes:
- 14x IBC MonoSol 360 (there is still space on the north/east side... does that make sense?)
- SMA SB 3.6-1AV-40 inverter
- DEHNcube YPV SCI 2MPP surge protection device
- Meter cabinet (+ accessories)
- Installation
The price is about 7,500€ gross.
The system will have a capacity of 5.04 kWp.
Currently, there are three people living in the house (2 adults, 1 child). Four are planned.
Our roof is quite simple but well oriented.
We are wondering if 5.04 kWp is sufficient?
Our electricity consumption in the apartment was always below 3,500 kWh per year, but we expect it to increase with the house. We estimate about 4,500 kWh.
Regarding the 24/7 electrical loads:
There will be an air-to-water heat pump from Novelan and a ventilation system with heat recovery.
I would really appreciate some advice.
We are building a semi-detached house and want to install a photovoltaic system on the roof. The orientation would be south/west and north/east. We intend to use most of the electricity ourselves. A battery is not planned, as the cost is quite high for such a system and it probably doesn’t make financial sense.
We have received an offer that includes:
- 14x IBC MonoSol 360 (there is still space on the north/east side... does that make sense?)
- SMA SB 3.6-1AV-40 inverter
- DEHNcube YPV SCI 2MPP surge protection device
- Meter cabinet (+ accessories)
- Installation
The price is about 7,500€ gross.
The system will have a capacity of 5.04 kWp.
Currently, there are three people living in the house (2 adults, 1 child). Four are planned.
Our roof is quite simple but well oriented.
We are wondering if 5.04 kWp is sufficient?
Our electricity consumption in the apartment was always below 3,500 kWh per year, but we expect it to increase with the house. We estimate about 4,500 kWh.
Regarding the 24/7 electrical loads:
There will be an air-to-water heat pump from Novelan and a ventilation system with heat recovery.
I would really appreciate some advice.
Here are the figures from yesterday.
Overall, over the last 3 days, approximately 100 Wh have been drawn from the grid despite the battery.
Yesterday, the electric car was charged. My wife then went to the hardware store at 11 a.m. and continued charging.
By the way, the dryer consumes 6 kWh.
Overall, over the last 3 days, approximately 100 Wh have been drawn from the grid despite the battery.
Yesterday, the electric car was charged. My wife then went to the hardware store at 11 a.m. and continued charging.
By the way, the dryer consumes 6 kWh.
Specki schrieb:
Well, since I occasionally need to tow a 750 kg (1650 lbs) trailer a few times a year for my own garden and my side business, it won’t work without it.
Overall, we only drive about 12,000 km (7,500 miles) per year and don’t need to go faster than 120 km/h (75 mph).
So actually, the Ioniq would be perfect if the tow hitch had a towing capacity instead of being only for bikes.
Anyway....
So, I just read my meters.
The meters were installed on March 20, 2020. Since then, I have the following readings:
Grid consumption: 303 kWh
Produced: 5013 kWh
Fed into the grid: 4408 kWh
From this, it follows that we consumed 605 kWh of the produced electricity ourselves, and a total of 908 kWh since March 20, 2020. This results in a self-sufficiency rate of 67%, and that without a battery.
I think that’s quite reasonable.
By the way, this is for 4 adults and 4 children between 3 and 10 years old.
And yes, we do try to use electricity during sunshine hours, but we’re not going overboard about it. Thanks for the numbers. You’re currently experiencing the best period. Enjoy it. In 10 months, you’ll be glad to have 30–35% self-sufficiency, and I’ll be happy to reach 60%.
Zaba12 schrieb:
Thanks for the numbers. You’re experiencing the best time right now.Well, I don’t really see April (with some March and some May) as the "best time." I think it might be more of an average period. That’s why I’m hoping to reach over 60% throughout the whole year.But I can only say for sure after a full year.
Specki schrieb:
Well, I don’t really see April (with a bit of March and May) as the “best time.” I think it might be about average. That’s why my hope is to reach over 60% on an annual basis.
But I can only say for sure after a full year. Here we had the best month since 2017 in April with a steep south-facing system. With your east/west setup, summer might be even better, but the sunny, cool days of the past weeks were really great for energy production.
Specki schrieb:
Well, I don’t really see April (a bit of March and a bit of May) as the “best time.” I think it might be more like average. That’s why I’m hoping to reach over 60% for the whole year.
But I can only say for sure after a full year. I can already dispel that hope for you. Just consider that starting from the clock change, nothing comes in after 5 p.m., and that’s when all the household activity begins—not counting the heat pump yet (at least in our case, or do you use gas for heating?). The only way to mitigate this is by scheduling the dryer, washing machine, cooking, and baking around midday. Even then, without battery storage, I don’t expect to see 40% self-sufficiency on an annual average.
Sunshine and not too hot is simply perfect. In midsummer, at 35°C (95°F), the efficiency drops because the heat cannot be dissipated as well (this is often compensated for by more hours of sunshine), but a consistently sunny April is, of course, best! It has also been the best month for me in a long time, better than any other month last year, and last year was already extremely good overall.
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