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Comment by dpcx | Hacker News Reader

Compared to the office buildings leaving their entire office illuminated all night even though the parking lot is empty, this is less than miniscule. In the grand scheme of things, yes, it matters. But start with the big fish and you'll be less hungry.

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While I agree with the overall sentiment (fix the big problems first to maximize payoff), the issue is one of attitude. Keeping a "save where possible" mindset, no matter how large the immediate payoff (within reasonable limits) has a much greater chance of success.

You have that effect in many areas of life. A quite obvious example is working out. Of course it won't make much of a difference if you skip today's workout or abort your 40 min run today halfway cause you don't feel like it. But it's the mindset/attitude. It makes you a quitter. It enables you to do the same thing again. And again. And in the end, the cumulative damage of the change in mindset is magnitudes worse than the single event.

> Keeping a "save where possible" mindset, no matter how large the immediate payoff (within reasonable limits) has a much greater chance of success.

Ironically that is what kept me from setting up solar power. Being in Scandinavia, solar has a somewhat limited potential given that days are 7 hours long during winter, and December often has less than 20 hours of sunshine in total. My calculations for the "payback" time of the solar panels said that _MAYBE_ they would have saved something before their "expiry date" some 20 years into the future.

Considering the "energy and material waste" involved in creating solar panels, this task can be handled by energy companies much more efficiently than i ever can.

I am still considering a share in a windmill though :)

This isn't the same thing - you've actually calculated that you're unlikely to save in this situation. You made a sensible decision that the payback period is so long for your own uses that it runs the risk of not actually paying back/being beneficial. The "save where possible" mindset would be more like "I calculated it would be better, but my impact is less than my workplace doing X, so I won't".

Everyone should be calculating payback on these investments every couple of years, because the calculus changes depending on incentives/tech/other factors (e.g. EV purchases, or massive cost of living changes)

So did the other poster - the energy to cool it from room temp to what they need exceeded (or nearly so) the energy to keep it running.

As a Norwegian looking into solar for my garage, all the products available now produce power when it's cloudy, snowy, rainy etc.

First Google result: https://www.energy.gov/eere/solar/articles/busted-common-sol...

I’m not saying it wouldn’t produce energy, and it would probably also contribute most of the year, but the time where I need the most energy (heating and light) is also the time where it is least likely to produce any.

We have an annual power consumption of 6-8k kWh, with about half during winter (heat pump, yay). More energy is required during night time due to dropping temperatures and it being dark, so realistically, I could probably save about half.

At normal energy prices of €0.3/kWh, that means I would save €1200/year, and that’s without taking into account reduced electricity taxes for electric heating.

Taking those into account, all electricity used beyond 4000 kWh/year would be around €0.12/kWh. Taking that into account, I could save €480/year, still assuming I could save 4000 kWh/year out of 8000 total.

A solar panel installation _without_ batteries is about €13500, and saving €480/year means it would take 28 years to get back the investment.

I’m aware batteries can change that equation somewhat in my favor, but it’s ever harder to calculate anything usable with those as it depends if the battery can get charged during the day. In any case, a solar panel installation with batteries is around €20000.

Yes, the ROI takes years to achieve but the alternative is to keep throwing money at the power company (and some of that energy will likely be from coal nowadays).

Since I bought an electric car I've been drooling over the idea of having the car powered by the sun. I go into the office only on occasion so I don't need to charge fast either. But you need an available roof and an okay topography.

But in Scandinavia, I bet most energy goes to heating so improving insulation and adding ground thermal will probably be more efficient. The idea of a sun powered car is just so enticing, however. It's kinda sci-fi.

> but the alternative is to keep throwing money at the power company (and some of that energy will likely be from coal nowadays).

This is Denmark, where a large part of our power grid is based on renewables, and backup power is based on natural gas. There is no coal involved. When we import power it's from Norway/Sweden or Germany, so either renewables or nuclear. We're not at Norwegian CO2 levels (yet), but it's getting better :)

You can check for yourself here : https://app.electricitymap.org/map

> Since I bought an electric car I've been drooling over the idea of having the car powered by the sun.

Denmark has outlawed sales of new ICE cars from 2030, so at that point solar will make MUCH more sense, as i can charge my car for "free", and the time to ROI will be much shorter.

> But in Scandinavia, I bet most energy goes to heating so improving insulation and adding ground thermal will probably be more efficient.

I thought so to, but currently, in no small part due to the Ukraine situation, lots of people are replacing oil and natural gas heaters with heat pumps or central heating, and the central heating providers are installing large heat pumps as well.

As part as getting a heat pump, my house (built 1970's and renovated 2010's) has a total heat demand of roughly 13000 kWh. Assuming a heat pump with a SCOP of 3.5, that means i will need about 3700 kWh of electricity to heat it, which means that our total electricity consumption ends up around 7500 kWh, so about half the energy (in my case) being used for heating.

Or, with how people work, harping on the little things causes them to run out of shits to give for even the big things and most will tune you out.

In my experience, anyway.

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