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You'll never get 100% efficiency from power storage so the amount needed per day is much higher. Lead acid batteries are 85-95% efficient for getting power in

by jws 15y ago

You'll never get 100% efficiency from power storage so the amount needed per day is much higher. Lead acid batteries are 85-95% efficient for getting power in and back out. It doesn't change your sizing much. That said, until a significant percentage of the utility's customers are using these devices, it makes no sense to use batteries. Just sell surpluses to the grid and buy back to handle peaks. If you have no grid, then about $1000 of batteries will cover you, and need replacing every 5-10 years. Either way, your inverter is probably around $2000. I'd have already clicked to buy in, except there is a missing chunk of the efficiency. Assuming I don't have a small lava flow next to a stream in my basement, what is the total projected efficiency of these units from fuel to electrical energy? They don't seem to be addressing burner efficiency. How will it compare to a small gasoline powered generator? (You can't buy a diesel genset this small.)

SwellJoe 15y ago
If you have no grid, then about $1000 of batteries will cover you, and need replacing every 5-10 years. This is wishful thinking, both on lifespan and cost of a household battery bank sufficient to run average household appliances like air conditioning and electric water heater and such. Even deep cycle batteries in this sort of working environment will need replacing every 3-5 years (and past 3 years, you'll probably be working with maybe half the capacity of what you started with). The workload of a household running off of batteries during periods when power usage far outstrips power generation is really hard on batteries. There are very expensive batteries that are rated for 5 years or more of use, but they cost two or three times what regular deep cycle lead acid batteries cost, making the total cost much higher. You'll also need more than $1000 worth of batteries for an average American household that uses air conditioning and electric heating devices. I live in a motorhome with a $300 battery bank (a motorhome has far fewer energy users than a standard home, and I don't run AC, microwave, or electric heaters off of the batteries; I have to crank the generator to use those), and solar on the roof. I'm very familiar with the limitations of batteries, and lead acid battery technology is extremely unforgiving of discharging beyond 50% (even beyond 75% leads to degradation, but most people in RVs accept that because the weight of carrying more batteries to be able to run at 75+% charge at all times is more costly than replacing batteries more frequently). But, I agree with you that selling back to the grid is the way to deal with this problem in a home on the grid. It's more cost-effective and more environmentally responsible.

by jws 15y ago

SwellJoe 15y ago

If you have no grid, then about $1000 of batteries will cover you, and need replacing every 5-10 years. This is wishful thinking, both on lifespan and cost of a household battery bank sufficient to run average household appliances like air conditioning and electric water heater and such. Even deep cycle batteries in this sort of working environment will need replacing every 3-5 years (and past 3 years, you'll probably be working with maybe half the capacity of what you started with). The workload of a household running off of batteries during periods when power usage far outstrips power generation is really hard on batteries. There are very expensive batteries that are rated for 5 years or more of use, but they cost two or three times what regular deep cycle lead acid batteries cost, making the total cost much higher. You'll also need more than $1000 worth of batteries for an average American household that uses air conditioning and electric heating devices. I live in a motorhome with a $300 battery bank (a motorhome has far fewer energy users than a standard home, and I don't run AC, microwave, or electric heaters off of the batteries; I have to crank the generator to use those), and solar on the roof. I'm very familiar with the limitations of batteries, and lead acid battery technology is extremely unforgiving of discharging beyond 50% (even beyond 75% leads to degradation, but most people in RVs accept that because the weight of carrying more batteries to be able to run at 75+% charge at all times is more costly than replacing batteries more frequently). But, I agree with you that selling back to the grid is the way to deal with this problem in a home on the grid. It's more cost-effective and more environmentally responsible.