ᐅ Evaluating the Proposal and Technology of a Photovoltaic System

Created on: 30 Jan 2023 12:00

hanghaus2023

Hello,

I am planning to equip my house with a photovoltaic system.

Electricity consumption: 7100 kWh per year
Southwest orientation, roof pitch 45 degrees

Most affordable photovoltaic offer:

23 * modules
Jolywood JW-HD108N-420W (frame: black, backsheet: glass)
- Best price-performance ratio: high nominal power of 420 W per module and an efficiency of 21.51%.
- Linear power warranty for 30 years (minimum 87.4% after this period).
- 25 years product warranty from the manufacturer.
- Half-cut cells: two separate cell areas connected in series reduce shading losses.
- Front and back glass with anti-reflective technology.

23 * modules DC installation including scaffolding

1 * Sungrow SBR096 9.6 kWh
- High-voltage lithium iron phosphate battery with multi-level protection concept and comprehensive safety certifications.
- Up to 30A continuous charge and discharge current with high efficiency and 100% usable energy.
- Plug & Play, no wiring required between individual battery modules.
- Of the total price, €4,476.16 net is allocated to the battery storage.

1 * Sungrow Hybrid SH8.0RT
- Three-phase hybrid inverter for residential use.
- Fast charging/discharging to easily manage consumption peaks.
- High self-consumption through optimized integrated energy management system.
- Remote firmware updates and customizable settings.
- Quick and easy installation, commissioning via smartphone.

1 * AC installation for Sungrow SBR096 9.6 kWh battery with Sungrow inverter(s)

According to the provider, the meter cabinet does not incur any additional costs.

Note:
The cost for the required additional electricity meter is not included in the purchase price. Your local grid operator is responsible for installing this meter and will charge you separately for this service.

Net price: €26,192

The provider is relatively new to the market and has 150 ***** reviews on Google.

Previously, I received offers with lower specifications starting above €50,000.

Is there anything to consider regarding taxes?

Honestly, I have no expertise in this area. Is there an expert here who can technically and financially evaluate the most affordable offer for me?

Thank you very much for your help from

hanghaus2023

RotorMotor19 Sep 2023 19:59

#79

kati1337 schrieb:

Well, we’ve been doing this for 19 days now, and we’ve fully charged the battery 19 times and fully emptied it 19 times in the morning?
In the mornings, we draw between 0 and 4 kWh from the grid, that’s it so far. This is not overly optimistic, it’s simply the current reality.

At some point, the fun of fully draining the battery every day might wear off and you might start consuming electricity during the day as well.

kati1337 schrieb:

Unless, for some reason unknown to me, September happens to be an exceptionally good month for photovoltaic power?

Not for photovoltaics, but the transitional season is indeed the best time for storage. The nights are already quite long (yes, including the evenings), yet there is still enough solar production to fully charge the battery.

kati1337 schrieb:

But with dual home office plus our appliances, the battery complements us exceptionally well.

Why would a battery be particularly useful for home office?
Especially then, you have the opportunity to charge the car during the day, run the washing machine, dryer, etc.

So despite your facts, I can guarantee you won’t fully charge and completely drain the battery every day.

kati1337 schrieb:

The battery is only allowed to supply the house. We have a PTH metering concept, where it is not permitted to charge or discharge the battery via the grid. Since we feed in surplus power, it must be ensured that no electricity from non-renewable sources is fed back into the grid.
Currently, we draw a maximum of 3–4 kWh from the grid, precisely when the battery is empty in the morning, so I am fairly certain that we are consuming our own generated electricity.

Your electricity meters are phase balancing.
You have three phases, and depending on the battery, it either feeds into one phase or all phases.
However, most of your loads are single-phase and likely draw power from different phases.
So even if the net balance is zero overall, it is quite likely that you are using grid electricity from, for example, coal-fired power while feeding your photovoltaic/storage power into the grid on another phase.

kati1337 schrieb:

But you surely notice: for us, the battery was also an ideological bet.

How can a battery be justified ideologically?
It doesn’t generate electricity.

I do understand the argument regarding uninterruptible power supply (UPS), though.

sysrun80 schrieb:

That alone is so typically German 😉 So utterly pointless it almost hurts.

Why is that?
What would be the point of a private individual feeding electricity into the grid that doesn’t come from a renewable energy system?
The feed-in tariff is an incentive after all, so the restriction makes perfect sense!

sysrun8019 Sep 2023 20:11

#80

RotorMotor schrieb:

What would be the point of a private individual feeding electricity into the grid that doesn’t come from a renewable energy system?
The feed-in tariff is ultimately a subsidy, so the purpose restriction makes sense!

Exactly! So why is it prohibited? Of course, it doesn’t make sense to buy electricity at 30-40 cents or even 18 cents, only to feed it back in at 8 cents 😉

But as described here: People can’t just use a dynamic tariff and charge their storage because they risk losing eligibility under the Renewable Energy Act.

RotorMotor19 Sep 2023 20:23

#81

sysrun80 schrieb:

Exactly! So why is it prohibited then? Of course, it makes no sense to buy for 30-40 cents or even 18 cents just to feed in at 8 cents 😉

Because otherwise people start doing strange things: feeding in from the diesel generator, from the car, and so on.

sysrun80 schrieb:

Just like described here: People cannot simply use a dynamic tariff and charge the storage because they risk falling outside the Renewable Energy Act.

That is of course not an issue.
You are allowed to charge the storage from the grid.
This is done occasionally and will also happen in winter when the small amount coming from the photovoltaic system goes directly to the heating, leaving nothing for the storage, which then risks running dangerously low due to its own standby consumption.
Yes, at that point the storage draws electricity from the grid—and that is allowed.

sysrun8019 Sep 2023 20:28

#82

RotorMotor schrieb:

Because otherwise people start doing strange things: feeding power from the diesel generator, from the car, etc.

Yes, some foolish ones. To repeat: technically, it’s straightforward – the aim is simply to prevent a few individuals from possibly making a few cents from this. The rest get hindered.

RotorMotor schrieb:

Of course, that’s not a problem.
You are definitely allowed to charge the storage system from the grid.
It’s done occasionally and will also happen with kati at some point in winter when the small amount coming from the photovoltaic system goes directly to the heating and nothing remains for the storage, which eventually risks running dangerously low due to its own standby consumption.
Yes, by then the storage draws power from the grid and that is allowed.

That’s clear. But that’s not what this is about here :-)

kbt0919 Sep 2023 20:35

#83

kati1337 schrieb:

Unless September is an exceptionally good month for photovoltaic power for some reason unknown to me?

The current September is already above average. You can calculate this with the PVGIS tool, and according to the latest data, my small PV system is at 131.8% of a "normal" average September.

kati133719 Sep 2023 20:36

#84

RotorMotor schrieb:

Maybe eventually the fun of fully emptying the battery every day will wear off, and you’ll start using electricity during the daytime as well.

We actually use as much electricity during the day as possible. We also load the dishwasher(s) in the evening but don’t run them until the next day when the sun is shining. The washing machine and dryer only run when it’s sunny. We optimize as much as we can that way.
The car only charges when the sun is out, not from the battery storage. That’s a personal luxury for us since we don’t commute and don’t need the car to always be at 90% charge. If it’s at 50% and it’s dark, we don’t have to charge it.
We don’t force ourselves to completely empty the storage. Instead, we try to reduce the last 4 kWh (kilowatt-hours) we have to buy at a high price in the morning. That’s why the goal is always to make the battery last as long as possible.
Right now, so much electricity is coming from the roof that we cover our load during the day, fully charge the battery, and still feed a good amount back into the grid.

PV-Dashboard: Donut charts showing PV yield 53.5 kWh and load 29.8 kWh.

PV generation 57.8 kWh and load 50.6 kWh with self-consumption and purchase.

What I don’t do, however, is give up my comfort to save electricity. I wouldn’t skip a bath in the evening just to save power. We optimize usage by time of day as far as possible, but we don’t go that far.

ᐅ Evaluating the Proposal and Technology of a Photovoltaic System

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