Comment by fpgaminer | Hacker News Reader

Comment by fpgaminer | Hacker News Reader

I'm so absolutely excited for solar power. Tesla's Solar Roof, their PowerWall batteries, electric cars. It's all just painting such a bright future. Certainly Tesla has no monopoly on it, but they've made it sexy and are pushing the bleeding edge forward. Props to them.

We recently signed a contract to do an installation on our house (with a local contractor, not SolarCity). It can't happen soon enough! We'll have enough panels and batteries to be 100% off-grid throughout the entire year, plus get a good chunk of change back from the Net Metering every year. Pay off is only 8 years!

That installation is enough to cover our normal electric usage. Longer term I want to replace our gas appliances with electric and replace the car with a Tesla. Then we can double our solar installation to keep pace and BAM we will be 100% clean energy and off-grid. All while saving a bucket of money.

The thought of running off grid in the middle of a Southern California suburb? People might think me crazy, but guess what? At least we're doing our small part to save the planet, and saving money doing it. So who's the crazy one?

Going off grid means you need a lot more batteries, which need materials and energy to make.

Switching from gas to electricity for heating is a bad idea if there's still coal power stations in use, if you're not selling your excess power to the grid, they're going to turn on that coal power plant again.

Sharing power is a much better idea than trying to store it in batteries, unless those batteries are in a car

> Switching from gas to electricity for heating is a bad idea if there's still coal power stations in use

You misunderstand. Our solar installation will be expanded to cover the appliances. We'll be 100% off-grid.

> Going off grid means you need a lot more batteries

We only need 3 PowerWalls to cover all our needs (~1 for our needs now, 3 for when we have electric appliances and a car). That's not "a lot more".

> Sharing power is a much better idea than trying to store it in batteries, unless those batteries are in a car

Huh? Why would sharing power be a better idea? Solar panels generate the majority of their power in ~4 hour window. Energy storage is _mandatory_.

Sharing power via net metering is better (for the environment) because there's no conversion loss from charging a battery.

Perhaps I'm not understanding the argument. My interpretation is that y'all want me to dump all my excess power during the day into the grid, to power other homes that don't have panels, instead of charging a battery. And that's somehow better for environment.

But ... when night falls, and I'm not generating any more power, where am I supposed to get power? Do I just live without power every night? And everyone else does too? Cause the only alternative is to burn fossil fuels to power everyone's homes during the night. Fossil fuels being perhaps the most inefficient solar batteries available to us.

And yes, fossil fuels _are_ batteries. Solar batteries in fact. It's just that they have an unimaginably terrible conversion loss, not to mention they're highly destructive to the environment, and take millions of years to charge. If they ever do recharge, which is unlikely, since our planet is not likely to revisit the eras that gave rise to significant quantities of them again.

I think I'll stick with lithium cells with their "conversion loss" of 80%, that take up a small portion of a wall in my house, and last for decades.

My points are: 1. To go completely off grid, compared to 80% off, takes many more batteries, and is therefore inefficient.

2. Using those batteries a lot every night wears them out more.

3. There are many alternatives to fossil fuels at night, wind, tidal, solar salt heating, nuclear, biofuels. Whether it's better to share or store would depend on many factors.

a) What power sources are used on your grid b) What the demand is at each point in the day c) The transmission efficiency vs the battery conversion efficiency d) The resource cost of the batteries

Until the power companies start devaluing your power because there's a surplus of solar on your street and they don't need it.

There are still a lot of places where the cost/efficiency of natural gas makes more sense.

Water heaters, stoves/ranges, etc.

>All while saving a bucket of money

I'd double check my math, because economic law says that's unlikely.

We're paying ~$19.5k for solar panels + installation. After the tax credit, that's $13,650 in cost. We spend ~$960/yr on electricity right now. The solar installation will cover all those needs, plus pay us $711/yr. So we're saving $1,671/yr. Pay off is thus ~8 years. The panels are good for 25 years. That's $28k in savings by the time the warranty runs out. They'll probably last longer.

The batteries are a different matter. I believe net meter makes them irrelevant, so the equation stays the same for most "sane" people. For me, I want to be off-grid, so I'm happy to pay a premium for batteries. That said, SGIP makes them roughly free if we get lucky. We'll see what happens.

That's much cheaper, than this article. Where is this?

SoCal

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