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Comment by throwntoday | Hacker News Reader

The point of solar on a camper van is to charge an auxiliary battery used for appliances. The range gains for the main battery pack are so minimal it wouldn't make sense unless the car spent the majority of it's time parked in the sun between locations.

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> it wouldn't make sense unless the car spent the majority of it's time parked in the sun between locations.

That's exactly what people do with these things. You drive them for a few hours. Then you park it and you go off enjoying nature, or whatever it is what people do while camping for the next few days. Most cars in fact don't drive the vast majority of the time. They just sit there parked for well over 90% of the time.

It's not going to make a massive difference to range of course. But even keeping the battery at the same level or slowing down energy depletion while you are camping helps. And best case, you actually leave the camp site with a bit more range than when you arrived there. That's useful.

Which I believe is true for most consumer vehicles. They spend most of their time parked somewhere and little time actually being driven. The same is true of people, they spend 95% of their time sitting and very little time actually being active. However, in both cases peoples perceptions are warped by their exposure to the activity, they only pay attention to their interaction with a vehicle or moving when they do it, so it seems to them to form a major part of their life when actually it is quite small. A well known psychological bias. It is a big surprise for many people when they buy an activity tracker and find out they don't actually do much most of the time. I used to drive two hours a weekday to and from work, about 20,000 miles a year. Using a car continuously all year at 60mph would be 60mph x 365 days/year x 24 hours/day = 525,600 miles/year. So 20,000 miles per year means using a car 3.8% of the time. The other 96.2% of the time it could be charging via solar (and it can charge while driving also). Still, the amount of power from 600W of solar panels on a van is not huge, 4.8kWH per day for 8 hours of intense sunlight per day. Could take a week or three to charge an EV fully. People can choose where to park, so it seems like enough to be useful in many situations. Having solar panels on an EV could mean it would never be truly stranded, though having to wait a day or more to get to a charger might be bothersome. In a rainy/cloudy season solar panels would have much less value. If it was a $500 option on a mass produced EV it seems worthwhile. At $1000 I'd think twice but might still buy it.

> The panel can charge the ID Buzz while parked or driving and is capable of generating enough power to provide an additional estimated 1,864 miles of range over the course of a year. Averaged out, that's just over 150 miles of range a month, which isn't massive, but hey it's something, right?

150 miles of range a month is like a week of free gas for the average commuter.

To put it differently, if I sit my ice car in the sun for a month, I get zero or possibly negative miles.

Average miles driven per year is 13,500 or around 260 miles per week. The better way to look at it is 1864 / 13500 which maximally gives you about 13% of those yearly miles "for free."

With WFH, I wonder how those averages have changed. Some folks are using cars much less often.

However, as someone who has prior experiences with keeping a low mileage car, I'd say parking it out in the sun is a terrible goal. You really want it garaged to slow purely time-based deterioration if you are not hitting high miles per year. A power hookup in the garage is the way to go, and then get house solar if desired.

So then, this car-mounted solar is only useful during an extended outing where you are away from your usual parking. Can it ever become cost effective for the value it provides in such short bursts?

Average is probably not too useful here because there are outliers who drive a lot. Median would be more interesting.

Those numbers seem widely optimistic and probably assume the panels are always optimally generating, when panel placement is a huge performance factor.

Those panels are maybe generating 0.1 kwh in the top quartile of exposure, and have a battery over 50 Kwh in capacity.

On an amazing day you may charge a single kwh. That's a 2% increase at best.

Every single naive person asks why they can't put a solar panel on a car and get rid of gasoline. They don't understand the surface to output relationship of solar power. This is mainly a marketing gimmick. Ideally those panels could be optimally placed and generate their full potential. Using them so inefficiently is a waste.

>Ideally those panels could be optimally placed and generate their full potential.

But then you're trading drag/weight for some system that angles them optimally.

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