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Comment by parl_match | Hacker News Reader

If you spent 10 minutes running the numbers, you'd probably answer your question pretty handily.

If I fully decked my roof out I can generate a good 20kWp

I'm assuming OP isn't actually serving out of home (starlink won't help with it's CG-Nat), so it's not like they're running 5kW of servers. 10kWh a day seems perfectly reasonable amount to keep going.

Given just running a generator it going to eat 20 litres a day on lowest load, over 3 weeks that's 400 litres you'd need to store.

With a battery setup even if you had to charge from a generator you'd be able to run it more efficiently for a shorter period.

So having spend 10 minutes I reckon the answer is "yes, OP should certainly get a solar/battery system set up"

That's crazy. There are huge differences is costs and use cases.A generator is $500, and mine can run for 24hrs on 5 gallons of gas. A 5kw solar system is about $25k to 35k in my area before batteries.

Solar is far cheaper than that in my location - especially if you put the panels up yourself, and storing 100 gallons of gas (400 litres) to run for 3 weeks is far more expensive.

I realize this isn't the case for everyone, but I already have a large propane tank that supplies the house. My generator is tied in to that. So I'm not storing fuel specifically for the generator, but if it came down to it I could probably power the house for a couple months at least. And our geography and flora are pretty unfavorable for solar. So as with most things, it just depends.

Storing 400 litres of gas in my area would cost about $250 USD for 2 new 55 Gallon barrels, maybe more if you want a nice pump.

I had a 10,000 gal tank put in for agricultural diesel, and that cost about $5,000.

> A 5kW solar system is about $25k to 35k in my area before batteries.

Do you live on the moon?

Earlier this year I installed a 7.8kW system in Canada for $13k CAD all in, inc the inverter and labor. (Then I got a $5k subsidy to bring it to $8k out of pocket.)

It’s cheaper now, panel prices fall every month.

California - the moon might be cheaper. The whole system here is corrupt due to regulatory capture.

There are high permitting costs, high cost hardware requirements, and high cost of labor.

The state requires a 4 years of training to become a solar installer, so there is little competition.

Also, with every new house required by law to have solar, installers know they have a captive market and are milking it for all it is worth.

I dont think we have yet seen the cost impact of the new Tariffs on Chinese solar panels and batteries, so it will keep going up.

> California - the moon might be cheaper. The whole system here is corrupt due to regulatory capture

I'm always amazed at how for regular life things it seems you guys has less "freedom" than we do.

It's my house, so I got up on the roof and installed the panels myself (with a friend). I did pay for a licensed electrician to wire the inverter into the main house breaker and double check everything, and he did get a permit for that work (which was $150, IIRC). Then I emailed the electric company, three days later they came out and installed a bi-directional meter for $32 and I'm good to go.

Depends on the price of batteries, which are rapidly declining. Within the next few years the numbers will change in favor of batteries. Though it also depends on the load and having enough space/sunlight for the solar array

I can buy a used diesel/propane/gas/pick your fuel generator today for a few hundred bucks that could power most of the essentials in my house. I bought a brand new one during an extended power outage due to storms last year for $500 CAD. That and 80L of gas (~$120 CAD) can run my sump pumps, fridge, freezer, the electronic side of my furnace, my homelab server rack (including 6 PoE access points), my workstation, and key lighting - for 5 days. If I cut that back to essentials, closer to 3 weeks. That’s roughly 200kWh for $120, plus $500 up front.

Currently, the absolute cheapest I can find lithium batteries (I am planning a solar+grid load-balancing setup) is about $160CAD/kwh. To prepare for the worst case (i.e. minimal solar generation during and following the storm - say, middle of winter/happens to be cloudy/panels are damaged/etc) I’d need to spend over $30,000 in batteries alone to have the same capacity as $120 of gas. Not to mention the sheer amount of space that would take. And the cost of solar panels (10kW actual generation capacity, minimum, to keep essentials running), at roughly $1/W in Canada, adds another $10,000 to that estimate. And that’s not including the cost of installation, which based on what I’ve heard, probably adds another $10-20k.

While there are some interesting advances being made, I do not believe that battery capacity costs will decrease by 3-4 orders of magnitude “within the next few years,” unless you anticipate gasoline/diesel/etc prices to go parabolic. It’s very obvious why people would much rather have a generator and some Jerry cans for a few hundred bucks than a solar + battery setup that costs more than their car.

> I do not believe that battery capacity costs will decrease by 3-4 orders of magnitude “within the next few years,”

Fair call for lithium chemistries, which will probably drop closer to one order of magnitude within 2-3 years (if the trend from the last year-to-date holds). But if we're talking about sodium ion, I wouldn't be surprised if that did drop by a couple of orders of magnitude, which is already sitting about ~140USD/kwh for consumer packs (but before shipping from China). It has a weird discharge voltage curve and needs a more capable inverter to handle it though, but at the prices I'm seeing, overcapacity is plenty affordable.

The solar and batteries have much lower emissions, and can be used as all times (not just during power outages) to lower the cost of electricity. Anyway it doesn't have to be generator or solar + batteries... Why not both? Have the solar, reduce emissions and utility bills. Have the generator as a backup if power is out and batteries are empty.

That's what I'm currently in the planning phases for. Break-even is still the better part of a decade on parts alone, unless you get very creative (for instance, where I live, I can choose to have a special time-of-use electrical billing program where overnight electricity is ~60% cheaper than usual; you can make use of this to charge batteries overnight, rely on solar when it's sunny, and batteries during the more expensive times-of-use).

The overall point though, is that solar and/or batteries are not a viable alternative for emergency backup power, nor will they be "within the next few years." Within the next few decades, maybe.

My quick math came up short on batteries. But as you say, it's worth running those numbers every year. I can't imagine I'll be sitting here in 2030 saying "batteries aren't there yet".

> I can't imagine I'll be sitting here in 2030 saying "batteries aren't there yet".

Or if you're looking now at sodium ion. It's only just hitting the consumer market, but it's already cheap enough for energy storage at the scale GP is talking about. Might take a few years for cell quality, inverter, and charging technology to improve, but by 2030 it will be so dirt cheap to the point that it would be economically sensible for any household.

Last year, when I did the math, batteries still had a 15 year payoff time. I'm not going to be in this house in 15 years. If the state subsidized it more (it is kind of a public good imo), or I could easily roll it into house value, I'd do it.

I'm trying to move to a nicer house. When I do that, I'll almost certainly just go for it.

I'm not sure whether you read my comment, but I was specifically talking about sodium ion which are absurdly cheap even before efficiencies of scale enter the equation. I don't think many are doing the math on that because it's only just become available on Alibaba. BMSes and chargers don't really exist for it yet, but there are whole battery packs for sale.

No, I read your comment. I was just thinking about 2030.

Also, no offense, but I'm not trusting a brand new energy storage technology bolted to the wall of my house. I'll businesses trial it out first for a few years.

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