I am having this dilemma from some months now, and I never thought ASR could be a place to ask.... but everywhere else I asked, the answers become fast political and are of little help.
Ok, the economic side:
I live in Luxemburg and even though my roof has a pretty good orientation and the government helps with the initial investment, the climate and the incredibly high installation prices vs neighbor countries make that we would need 7-10 years to break even, and at that point we might have to start thinking on replacing the battery (? not sure what is the state of the art). All in all it seems a pretty bad investment on my book.
That break even time was pretty typical for PV installations a couple of years ago. Should be slightly lower today, but maybe it isn't in Luxemburg due to the high labor costs.
After 10 years, you absolutely do not need to replace the batteries. You can always have bad luck and see individual cells die an early death, but battery warranties today are 10 years already for the big brands! With LFP cells, you can expect a lifespan of
more than 5000 full cycles. That's over 13 years if you assume a full cycle every day, which you will not reach in real life. And at that point, the batteries are not dead - they are just around 20% degraded, which doesn't prevent you from using them in any way. It is more likely that you might need to replace the inverter after 10-15 years, but that cost is manageable.
People tend to counter this saying that the panels allowed them to have the AC running full power all summer, but we are more windows wide open kind of people, I wouldn't want air conditioning even for free.
On the environmental side things get much more complex, and this is the part I struggle more having a meaningful conversation with anyone, as people tend to rely on very simplistic arguments.
Filling the house with hundreds of kg of electronics, batteries and structural elements that for sure carry a heavy footprint to have them working well below their possibilities in central Europe doesn't seem like a no brainier to me unless someone shows me the numbers. And most especially when a good chunk of the electricity we buy today is from renewable sources. I know there are a lot of caveats here,and that my money will also help suppliers to keep advancing the technology, but my point is that I don't have enough information to make an informed decision.
The equivalent specific CO2 release per kWh for PV over the full life cycle is
significantly lower than that of the grid in Luxemburg for pretty much any installation type except maybe for those on facades facing north.
Another argument to postpone the investment is the expectation that the technology evolves further, especially on the battery side. Also reverse charging (or whatever it is called) using a car battery sounds attractive, but is not available where we live at the moment.
Would love to hear your opinions and would love to be proven wrong. Thanks!
The car battery is nice in theory, but useless for most people in practice:
- The car needs to be at your home for this to work. So if you are at work from 8 - 16 o'clock, you can only charge for a couple of hours in the evening (+ limited to the summer) and you need some of that charge to actually drive the car
- You will significantly increase the wear of the battery and - in contrast to home batteries - a degradation of 20% after a couple of years is relevant for a car due to the reduced range
I'm sure there are even more arguments against it. Vehicle to grid might be useful in the future for short term grid stabilization (minutes), where you rent out a couple of kWh of your car battery to some utility company or an intermediate broker. For home storage, I'm convinced that it is and will stay useless, because it's not available for large stretches of the day.
Concerning the technology advancing: It always will. Outside of a small window of early tech adoption where teething problems are expected, I would not use this as a counter-argument for any evaluation of tech investments. If it is economically feasable right now, it's a good time to buy. If you wait, prices may drop further but you also miss out on the return on invest within that time frame. And there could just as well be another random global crisis tomorrow driving up lithium prices and making batteries much more expensive for years. Nobody can predict the future.
and I have done it in the past with other large (for me) investments. To give you an idea, at the he of 50 I have only driven two cars, and one of them I bought it used.
