ᐅ Evaluation of Solar Power System Proposal with Battery Storage

Same Sungrow system including the storage. However, 24x 425W Trina Solar modules. All-in (including scaffolding, etc.) just under 19,500 euros.

Hello, thank you for your comments. I will try to compile the consumption data and determine to what extent we can actually discharge the storage system in the evenings and at night.
Of course, you have to consider that the children will grow up, maybe we will get an electric car at some point, and I cannot predict the future. Currently, we definitely use relatively little electricity and between 10 p.m. and 6 a.m., apart from the standard devices, we hardly consume any power.

I just thought of something else: The heat pump can also cool in summer. Would that still be relevant? Although the majority of consumption probably occurs during the day here as well.

sysrun80 schrieb:

Same Sungrow system including the storage. However, 24 x 425 watt Trinasolar modules. All-in (including mounting structure etc.) just under 19,500 euros.

Thanks for the comparison

We have a 5kWh (6 kWh) battery storage system and rarely manage to fully deplete it during the summer. This is despite having a very high energy consumption due to numerous systems such as controlled ventilation, an air-to-water heat pump, smart home technology, cameras, networking equipment, servers, and so on.

All this equipment together uses about 250W. However, a 5kWh (6 kWh) battery can still supply power for almost 20 hours, and even in the depths of winter, the nights aren’t that long. As a result, in winter, the battery storage sometimes doesn’t fully charge for several days, and in summer, it doesn’t fully discharge during some nights.

This means we cycle the battery about 220 times per year. For us, the battery only makes sense because, thanks to KFW40+ standards, it was almost free.

How Kati fully depletes such a large battery every day is still a mystery to me.

Further questions/feedback regarding points mentioned by @kati1337:
- Hot water with a heat pump: This should use a maximum of 2kWh (2.4 kWh) per day and can easily be scheduled around midday instead of at night.
- Gaming: What is the power consumption of your gaming PCs? A current gaming console uses about 200W, plus 100W for the TV. So even if you game for a few hours in the evening, you won’t empty the battery. For example, 4 hours would only use about 1.2kWh (1.4 kWh).
- Home office: For most people, this ends when the sun goes down (except in winter, but then the battery is rarely fully charged anyway).
- Electric car: Especially during home office days, you usually charge it during daytime, not from the battery storage at night.
- Do you have any charts showing when different consumers are active and what the baseline power consumption is when the gaming PCs and heat pump are not running?

RotorMotor schrieb:


I still find it a bit of a mystery how Kati manages to empty her huge battery storage every day.

Additional questions/feedback on points raised by @kati1337:
- Domestic hot water with heat pump: should use a maximum of 2 kWh per day and it’s perfectly possible to schedule it for midday instead of nighttime.
- Gaming: How much do your gaming PCs consume? A current gaming console requires about 200 W, plus 100 W for the TV. So if you play a few hours in the evening, you wouldn’t empty the battery storage either. For example, 4 hours would only be about 1.2 kWh.
- Home office: For most people, work stops when the sun goes down (except in winter, but then you usually can’t fully charge the battery anyway).
- Electric car: Especially when working from home, you obviously charge it during the day, not at night from the battery.
- Do you have any graphs showing when which devices run and how high the base load is when gaming PCs and heat pump aren’t operating?

- I’m still waiting for a proper introduction to our heat pump systems from the plumbing company regarding domestic hot water. We would need the network module to connect the heat pump to the system, but we’ll buy it when we have some spare money. Currently, I’m still somewhat in the dark with the heat pump. We will probably disable the heat pump’s nighttime hot water generation once I know the exact size of our battery storage and so on.
- Both gaming PCs have 650 W and 700 W power supplies, plus 4 monitors and various other small devices in the office. These run significantly longer than 4 hours a day.
- When the home office computers are off, the personal computers turn on. There’s always something running: YouTube, news, eBay, emails, communication—everything goes through the PCs here. The TV is only switched on once a week in the evening.
- We do charge the electric car during the day, for sure.
- The base load at night is about 400 to 450 W.

When I look at live consumption in the evening (after the kids are in bed and we’re on the computers), we’re drawing around 1500 W.

kati1337 schrieb:

- We will still turn off heating water at night once I know how big our storage tank is, etc.
- We charge the electric car during the day, of course.

That’s already a good start!

kati1337 schrieb:

- Both gaming PCs have power supplies of 650 and 700 watts, respectively, plus 4 monitors and various other small devices in the office. These run significantly longer than 4 hours a day.
- When the home office computers are off, the private ones are on. Something is always running. YouTube, news, eBay, emails, communication – everything goes through our PCs. The TV is turned on only once a week in the evening.

Just because the power supplies can handle such a peak load doesn’t mean they actually consume that much. Especially for YouTube, news, and similar use, the power consumption should be quite low even on modern gaming PCs. It is quite surprising, though, that despite work, kids, and a new house, you manage to spend well over four hours on them daily.

kati1337 schrieb:

- The base load at night is around 400-450 watts.

That is really quite high! I would definitely get an overview of all the devices contributing to that load. It’s not only bad for the environment but also unnecessarily heats the house and ultimately increases costs.

RotorMotor schrieb:

That’s really quite a lot!
I would take a look to get an overview of all the appliances involved.
It still harms the environment, unnecessarily heats the house, and ultimately also generates costs.

What would be a normal value?
Maybe I overestimated a bit; I only looked at one night as an example. I think 350–400 is more realistic.
We also just thought about what our appliances run at night. We usually turn off the computers completely. I guess this is the classic standby trap. We have a large house, so there are many sockets with quite a few devices plugged in. The usual suspects come to mind: refrigerator, second fridge/freezer, two dishwashers, four monitors (which turn off by themselves but probably still draw standby power), a few game consoles, stereo system, several Alexa devices, baby monitor, washer/dryer, network equipment in the utility room, child’s night light—each of these probably doesn’t use much on its own, but adding them all up + whatever I’ve forgotten, it adds up.

Edit: The game consoles can’t really be counted yet; only the PS4 is currently plugged in. I don’t know yet what the heat pump consumes during summer operation. But the ventilation system probably draws a lot as well. I’m missing the network connection info; it’s possible it’s running full power day and night without switching to a lower setting.