Comment by rhodozelia | Hacker News Reader

Comment by rhodozelia | Hacker News Reader

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The unit stores 40 kWh and can generate 5 kW from the fuel cell at an efficient of 62.5% and an additional 5 kW boost from a battery for short intermittent peaks. So it will basically take 5 days to use all of the stored energy with no charging if you are running 40 amps of continuous loads at 120V. That’s pretty good. Not enough for a stove or electric heat but definitely enough for all your lights and appliances and a small air conditioner.

What is great is the 30 year Lifespan vs. 5 years expected from batteries in grid scale storage applications.

80% charging efficiency and 50% round trip efficiency yields 62.5% generating efficiency. To charge 40 kWh at 80% efficiency would take two 10 hour days with 9 three hundred watt panels. But you’d want to power your loads those days too, so probably a 20-25 panel array would be an appropriate size. 25 three hundred watt panels is $8k CAD. On top of the $22k USD for the hydrogen storage. Pretty decent setup for $30k!!

rhodozelia not sure of your math there. 40kwh outputted at 5kw I make eight hours of use at max output? It's winter here so I'd say many households would empty it in less than two days easily. Equally in winter here 4kw of solar panels output about 4kwh's a day. So about two weeks to charge the battery and nothing else... Of course it's summer in Australia so much more solar output but you would be better putting it straight into your AC rather than storing it? Apart from running AC at night? $35000. That said if they can really get it to chug away for 30 years mainantance free unattended I can certainly see useful niches.

you are right it is 5 hours not 5 days!

I wonder how it would compare against Nickle Iron batteries?

https://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery

I guess the use case might be arguably different - the hydrogen storage could last a week or a month, which the battery would self-discharge.

i own a grid tied 15x325Watt system which gives me around 25 units (25kwh) if electricity in summers. i have thought of a crazy idea of a water battery that would get charged with a solar water heater as well as the solar panels to heat the house in winters...

the USD 22k is wayyyyyyy too expensive

Lol your grid tie systwm comes to 4.8kw if your (15*.375) is correct. We rip around 20kw a day on a AVG house in Aust. My folks shred through 30kw an that's just 2 people.

Given power used to be about $3k a quarter or $12k a year for them...it's only 3 years of bills to cover a 15yr battery. They already got 8kw of solar for 13k too. Not bad at all really, $45k for battery an solar, pays for itself in 4 years if your use is high enough. 11 years of savings before you replace the system.(aus dollars)

sounds good but i paid less than USD 1200 for the panels, inverter, cabling, installation.

Our monthly power consumption is around 300Kwh in summers (no need for air conditioning) and double in winter months (need heavy heating but no electricity due to low supply/heavy snow). that gets to around USD 200-250 for a year. that gives me 22000/250=88 years of no electricity bills to repay this system. Note, my Kwh is USD 0.05

the country is india where due to USD exchange rate which is INR 73:1 USD.

My god I'm jelly of those prices. Aust is 27-32cents a kWh for grid power. About 1$ per watt for solar panels. If you feed back into grid you get paid 16ish cents per kWh.

Oh. We arent paid or anything, just the reading is supposed for a year to year and I have to pay just 10% of my last bill. Say I consume 1000kWh for a year and generate and sell to them 1100kWh, then I still have to pay for 100kWh at same prices.

I could reduce my load on grid by going battery but that is very expensive and with lead acid the ROI doesnt reach as they get depleted in 3 years before any profit is made. Havent looked at lithium as its very expensive..... will see

If the policy for net metering changes in future, I will preemptively buy another 5-10 kWh panels

You have a source on the 5 years life expectancy of battery systems ?

It was relayed to me by a mathematician doing the analysis on sizing a battery system at a solar plant in Hawaii. The trade off between decreases longevity with depth of discharge or increased up front costs for more batteries that don’t get discharged as deeply.

Yeah that seems too low to me, given that a lot of electric vehicles warranty their batteries for 8 years, and those batteries typically undergo more stress in terms of peak charge/discharge and such (and also would be expected to normally last beyond the warranty period - it’s not like they all drop dead after 8 years and one day).

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