Today's Hebel: Are Solar Panels and Batteries Really Necessary? 'Calculating the Cost-Effectiveness of Natural Energy'

Today's Hebel.

When building a house, natural energy equipment like solar panels and storage batteries is often considered something you 'should install'.
They are excellent for environmental considerations and disaster preparedness, and they are standard equipment recommended by housing manufacturers.

I initially accepted this as 'just how it is,' but they are by no means cheap purchases.

Depending on the size and specs, I've heard that solar panels cost roughly 1 to 1.5 million yen, and batteries cost around 2 million yen.
Thinking that this alone would increase construction costs by 3 to 4 million yen, I couldn't just easily decide to go ahead with it.

So, instead of blindly accepting the benefits touted by society, I decided to simulate what would happen in my own home over a long-term span of a 50-year loan.

To conclude, my home's choice was:
'Install as many solar panels as possible'
'Skip the storage batteries and EcoCute'
Here is a simple summary of the calculated results.

[Solar Panel Simulation]

Conclusion: Adopt (Positive cost-effectiveness)
* Initial cost: Approx. 1.2 million yen
* Monthly loan increase: Approx. 2,600 yen (at 1% interest, 50-year loan)
* Electricity sales income: Approx. 3,000 to 4,000 yen per month (selling surplus electricity)
* Savings from self-consumption: Approx. 5,000 to 6,000 yen per month (savings from not having to buy expensive electricity during the day)
* Nighttime electricity purchase: Approx. 8,000 yen per month (you buy it normally since there is no sun, but this occurs regardless of whether you have panels or not)
* Net balance: Approx. 6,000 yen surplus per month
By incorporating it into a long 50-year loan, the monthly repayment burden drops to just 2,600 yen. Meanwhile, the value generated by the panels (sales + savings) far exceeds that.
It doesn't mean the electricity bill becomes zero, but when comparing 'with panels' to 'without panels,' the calculation shows that several thousand yen remain in hand even after subtracting payments. There is no reason not to install them.

[Storage Battery Simulation]


Conclusion: Skip (Cost-effectiveness does not match)
* Initial cost: Approx. 1.5 million yen
* Daily savings: Approx. 70 yen (details below)
* Total recovery over 15 years (estimated lifespan): Approx. 380,000 yen
Now, those who are good with numbers will have a question here.

'If you are paying 8,000 yen a month (about 260 yen a day) for nighttime electricity, wouldn't you save much more dramatically if you used a battery to cover nighttime electricity?'

Actually, this is the biggest trap in storage battery simulations.

The electricity stored in the battery is 'surplus electricity generated by solar power during the day'.

If there were no battery, this electricity would have been 'sold' to the power company at about 16 yen per kWh.
In other words, even if you cover expensive nighttime electricity (about 30 yen/kWh) with a battery, you don't save the full 30 yen. You are just 'avoiding buying 30 yen worth of electricity' while 'throwing away the 16 yen you would have received if you had just sold it'.

The actual economic benefit is only the difference, which is '14 yen per kWh'.

Even if you cover 5 kWh per day with a battery, 14 yen x 5 kWh = only 70 yen per day.

It calculates to only about 25,000 yen saved per year.

Paying 1.5 million yen and only being able to recover about 380,000 yen by the end of its lifespan.

In my calculations, the cost-effectiveness never worked out.
There is also the idea of 'insurance during a power outage,' but in an area that hasn't had a power outage in the last 10 years, if I were to invest 1.5 million yen in that risk, I would choose to sleep soundly on the night of a power outage.

I also skipped the water heater (EcoCute, etc.).

I understand the rationality of late-night electricity, but I am an avid bath lover.
Worrying about running out of hot water in the winter while asking 'how many more liters can I use?' is a bit different from the freedom I was looking for in a custom-built home.

Also, I couldn't shake my personal resistance to the hygiene aspect of a structure that reuses hot water stored in a tank.

In the world of NARUTO, there is 'Sage Mode' that incorporates natural energy.

It is very powerful, but if the user does not perfectly balance their own chakra with external energy, they will turn into a stone frog statue.

The equipment for building a house might be the same.

If you incorporate things that are said to be 'good' without a plan, your household budget balance will collapse, and you could end up as a heavy stone statue named a loan.
Recalculating based on the size of our own lives was, in a way, like training to avoid turning into stone.

...And so, I have spoken as if I had done meticulous calculations, but in fact, I just threw the costs and specs of the equipment at an AI and had it calculate everything.

I'm worried about whether to install storage batteries and solar panels.

Calculate the cost-effectiveness.
It gave me the above just by telling it that, so I just followed it.
My, what a convenient era we live in.
To be continued.

#HomeBuilding
#CustomHome
#HebelHaus
#MyDessin