I wrote about solar panels earlier this year. We have met with three different solar companies in our prefecture and have been crunching the numbers to see what works and doesn’t work for us. We are torn between being more off-grid while also making sure this investment is also worth it in the budget department.
The process is simple- You send them a blueprint of your house along with the annual average of your electric bill. They look at the roof angels and space and your annual average and come up with 2-3 different brands and plans for your solar panel and/or battery set. They come and scope out the amount of sunlight you get around your house and talk about their company and the plans they made up for u over a cup of tea and you get back to them if you have any questions or want to process with the contract. This is BEFORE the construction people come and make sure everything is okay. They assured me that it shouldn’t be any problem but because of COVID, they don’t want to send a bunch of construction people into people’s home beforehand. Makes sense.
My partner and I have discovered that we don’t use a lot of electricity! We used a total of 4123 kWh last year and our average monthly bill is about 7200 yen. Does this low monthly average mean that we won’t save as much with solar panels, meaning it will take us longer to pay it off?
Well, yes and no. For example, all three companies suggested 4 kWh solar panel systems for us which, depending on maker, comes to around 90 man – 100 man yen which includes construction and one free maintenance after one year. The different makers offer different size panels to fit our roof and while calculating on the low-range (more rainy days and more snow than we usually get), it will generate around 4300 kWh for us in a year.
Then we made some calculations:
Daytime (7am-5pm) usage Kwh – estimated 4300 kWh = Leftover kWh
Leftover kWh * 19 yen = how much money we will make selling our leftover kWh back to the grid.
Money we make selling + Money we would have spent on daytime usage = how much we “earn”
Price of the solar panel system / how much we “earn” = how many years it takes for the solar panels to pay for themselves
Doing this, we found that the solar panel system will pay for itself in about 7-8 years. That’s not bad since we can probably get another 12 (hopefully more) years out of the panels itself. All the companies are also offering a 25 year warranty, which is comforting.
The problem is the battery. My partner was set on getting a battery because this whole solar panel talk started because of the black outs from the snow that fell upon many parts of Nagano this year. The recently earthquake was also a cause for concerned. However, the batteries are unbelievably expensive! It seems that lithium battery is the main one used and it’s also the most expensive. Same as the solar panels set, if not more. They are also only under warranty for 10-15 years depending on which maker you go with and according to a quick google search, they have a lifespan of about 15 years.
After the ten years is up, we can no longer sell our excess battery. Our plan was the have the battery to store the power and use it during the rest of the evening and night time and hopefully can be totally off-grid if needed.
However, since we use an ecokyu to heat up our water, the battery isn’t large enough to be used for that as well as our night time usage. Without the income from selling our power combined with our rather low electric bill/usage, it will take over 20 years for the battery to pay for itself…which is insane! While Tesla’s Powerwall is the cheapest and one of the best options in Japan, there is a three year waiting list at the moment.
So there is a slight change of plans!
Ditch the battery and just go with the solar panels for now! A good and sound suggestion from RetireJapan. Our ecokyu uses up all of our night time usage at around 2kWh for roughly three hours. However, our nighttime rate is at 13yen so we aren’t hurting much from it. Who knows how much batteries will cost in ten years time and since we intended to sell any excess power for the first 10 years to maximize our earning, it won’t put a dent in any plans.
That’s all for the solar update for now. We have yet to make any firm decisions but would love to hear from all of the readers out there. For those with solar panels, have owning the system meet your expectations? Let me know!
Forever Friday- Retire in Japan 