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Comment by Retric | Hacker News Reader

In terms of power / weight solar can already beat many IC engines.

The only thing more efficient solar brings is less packaging and use in extremely confined spaces like the roof of a car.

PS: The car thing should start taking off in a few years. A Tesla model 3 is 4.6 meters long 1.85 meters wide so 8.7 meters square. At 40% your talking about around 30kwh per day which could really extend the range and for less used cars minimize recharging.

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Why is weight an issue when we are talking power plants for housing?

Here's a 8.3 kW diesel generator (6.3 kW generator) from Home Depo: https://www.homedepot.com/p/Boss-Precision-Products-Inc-Port...

3900 USD.

367 lbs + fuel = 180 kg + fuel

http://www.nordensolar.se/produktdetaljer/solceller-luxor-so...

One random 265W solar panel, you need 31 off them, one is 18,6 kg gives 582 kg of solar panels to get to 8.3 kW (obviously you wont get 8.3 kW cont. from them). Not counting inverters, mounting rackets etc.

So for equal weight and way more power you have one 8,3 kW diesel generator and 402 kg of diesel.

1 kg diesel is ca 12 kWh energy. Lets guess 30% efficiency gives 1447 kWh electricty for the same weigth. That's about as much as the solar panels will produce in 2,4 months assuming 129 kWh/m2/year.

According to this site it's 3,14 USD per watt solar panel installation for consumers. https://news.energysage.com/10kw-solar-systems-compare-price...

8300 * 3,14 = 26 000 USD.

So, you can buy a generator and 22 000 USD of diesel (about 22 000 litres or 22 000 litres * 10kWh * 0,3 efficiency = 66 000 kWh electricty) for about the same price. Or about what the same dollar in solar panels will produce in 8 years with way lower peak power.

Backpacking is one example where you want lightweight solar power, but aircraft and balloons are a more extreme example. In such cases those stiff panels are a long way from what you want. Also, good luck averaging 30% effecency from a basic diesel generator for home use.

Without going to extreme: https://www.solbian.eu/en/4-flexible-solar-panels

That’s 130 W for 1.7kg. Your 8.3 KW would be 108kg which is 238 lb and thus less than the generator even excluding fuel.

Ye, of course. But the comparison was with ICEs and given that you could bring an ICE weight carrying capacity is usually not that scarce like back packing or balloons.

Depends on if you need power, or, energy over time for the same weight.

Weight is often an issue to some degree. For example the US military has adopted solar for many remote bases because moving fuel is a logistical issue.

Again, I think for the most common case the only real advantage of increased effecency is lower installation costs. I am just saying solar fits in a very wide range of use cases and sometimes say for satilites you want something very specific and paying for it is worth it.

there's an extremely efficient diesel engine called the Lister CS that became popular in the 1920s. It's claim to fame is that it can run 30-45 years without major maintenance and produce 1kwH per .125 gallons of diesel. That's 8kwh per gallon. It was banned in 2009 by the Obama administration because it was considered fuel inefficient by bureaucrats who didn't understand the design. There was a movement to try and de-list it from the ban. My dream has been trying to find one and draft it into freecad so people could 3d print cast iron molds and re-manufacture them. https://youtu.be/NhAD8D3sM2A?t=98

From what I can tell, the Lister was banned because of carbon particulate emissions, not due to efficiency. However, very slow turning engines like the Lister tend to have a more complete combustion and lower emissions.

>>can run 30-45 years without major maintenance

I think it would be better to list the number of miles it can run before maintenance is needed. Just stating the time does not provide a complete picture.

Woah, 30kwh =~ 210 km... that could eliminate charging on even moderately used cars.

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