TheEquineFencer
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Solar and Utility power switching sources?
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TheEquineFencer
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Bretny
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Generator transfer switch could do what your asking.
kd3pc
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marine shore power transfer switch will do exactly what you want to do.. Check out eBay for Blue Seas or other model
You'll have to BUY a generator transfer switch though. a grid tie inverter is the right move here, at least if you care about ROI. it doesn't make literal cents to draw down lead acid batteries and recharge them when you have the grid available. keep them in float charge and use the power directly.
or spend nothing and waste money.
anyways code requires you to use a transfer switch that does not allow for the possibility of feeding inverter power back into the grid.
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TheEquineFencer
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Time to get ticked off then. i'd hardly call that free. operating a solar + lead acid battery system costs more per kWh than grid power.
I already answered question 1. you need a transfer switch that cannot backfeed the grid with your inverter output.
2. yes, you can have multiple power sources feeding different panels - doesn't matter if they're solar/generator/UPS/kid-on-a-bike-power. it sounds like you need to start doing some research.
I already answered question 1. you need a transfer switch that cannot backfeed the grid with your inverter output.
2. yes, you can have multiple power sources feeding different panels - doesn't matter if they're solar/generator/UPS/kid-on-a-bike-power. it sounds like you need to start doing some research.
Bretny
Well-known member
The power you can make at home is always going to cost more than what the power company can provide you. Unless we are talking about a grid tied system and tou get ALOT of sun. Once you go adding batterys to the system and a charge controler your more expensive than the power companys power.
Buy a generator.
Buy a generator.
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TheEquineFencer
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TheEquineFencer
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TheEquineFencer
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TheEquineFencer
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TheEquineFencer
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TheEquineFencer
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TheEquineFencer
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TheEquineFencer
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HOTFR8
Banned
Would be much easier just to have a smart inverter that can connect or disconnect from the grid as I have. Otherwise why not set up the Solar to stand alone separate from your grid power and I have done this as well.
American Locomotive
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You can do whatever you want inside your own garage. Code only matters when its time to sell, you get electrocuted, or your house burns down. If you want dedicated solar-powered circuits, go right ahead and put them in. You could switch your lighting and small loads circuit with a Triple-Pole-Double-Throw contactor/relay. Make sure it's rated for whatever the feeder circuit is capable of delivering.
As to the others saying "generating your own power at home is always more expensive" - that is only true if you're actually generating power from some sort of fuel source. Solar has a fixed one-time investment cost. Provided your batteries last a long time, and you have decent panels that don't degrade fast - it'll make "free" electricity once the initial cost is paid off.
Grid-tie inverters are great if you have constant high-power draws. However if your house usually has low power draw, grid-tie may not be all that great for you during the day, and will not help you at night. Many utilities will not pay (or allow) for grid-returned power, and if they do, its usually at a lower rate than they sell power to you. Additionally, grid-tie inverters are designed to shutdown if the mains loses power.
Battery-tied solar systems allow you to store and use power as you please. If you have low-demand during the day, your batteries will charge up all day. Once night time hits, you can start drawing off the batteries. With a large enough system, it's conceivable you'd never have to use power from the grid at all. However, your limited by the size of your inverter and battery system, and it's also less efficient.
There are pros and cons to each system, and it sounds like the OP has it figured out what he wants from his solar system.
As to the others saying "generating your own power at home is always more expensive" - that is only true if you're actually generating power from some sort of fuel source. Solar has a fixed one-time investment cost. Provided your batteries last a long time, and you have decent panels that don't degrade fast - it'll make "free" electricity once the initial cost is paid off.
Grid-tie inverters are great if you have constant high-power draws. However if your house usually has low power draw, grid-tie may not be all that great for you during the day, and will not help you at night. Many utilities will not pay (or allow) for grid-returned power, and if they do, its usually at a lower rate than they sell power to you. Additionally, grid-tie inverters are designed to shutdown if the mains loses power.
Battery-tied solar systems allow you to store and use power as you please. If you have low-demand during the day, your batteries will charge up all day. Once night time hits, you can start drawing off the batteries. With a large enough system, it's conceivable you'd never have to use power from the grid at all. However, your limited by the size of your inverter and battery system, and it's also less efficient.
There are pros and cons to each system, and it sounds like the OP has it figured out what he wants from his solar system.
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TheEquineFencer
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TheEquineFencer
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Code is there for safety of you and others. the reason code specifies the narrow blade is hot and the wide blade is neutral isn't just to "be code", it's for appliances that used a neutral bonded metal cabinet - if you flip L and N on an outlet and plug that in, you have a HOT box sitting out! if that circuit gets completed to ground/neutral by anyone/anything, bad things happen. if it happens to someone else because you play with that attitude, you might end up on the hook for whatever happens because of it.
It's always more expensive, even for solar, just by factoring in the cycle count and capital cost of the batteries.
about $0.28/kWh for flooded lead acid. grid power costs half that. the only way it's cheaper than grid power is if you get your batteries for free.
http://webs.wichita.edu/depttools/d...Hour to Store Electricity final published.pdf
Mind you if you're factoring in the cost of having power lines run to your house because you're building where they won't hook you up for a marginal cost, then that's different.
Either way li-ion has a better cost/kWh than lead acid due to the short lifespan of lead acid when used beyond 50% DoD. Failing to fully charge lead acid on a daily basis causes additional wear.
if you're comparing solar+batteries to a generator, then you might come out ahead, or not. a standby generator with a full fuel tank won't degrade much if well protected from the weather (both the fuel and the generator). possibly longer than the standby lifetime of a set of lead acid batteries.
The only way to see actual return on investment with batteries is to do a grid-tie with battery backup. this keeps the batteries charged for maximum lifespan, and you sell any surplus generation back to the grid. this gets you UPS grade backup power if done with modern equipment (double-online or standby style), and if you live in a place that does time-of-use or event priced power, you can switch to battery for load shaving whenever the price point makes sense.
Long-term testing of solar panels shows them to have 80% or better output after 20+ years of use. that seems pretty solid.
It's always more expensive, even for solar, just by factoring in the cycle count and capital cost of the batteries.
about $0.28/kWh for flooded lead acid. grid power costs half that. the only way it's cheaper than grid power is if you get your batteries for free.
http://webs.wichita.edu/depttools/d...Hour to Store Electricity final published.pdf
Mind you if you're factoring in the cost of having power lines run to your house because you're building where they won't hook you up for a marginal cost, then that's different.
Either way li-ion has a better cost/kWh than lead acid due to the short lifespan of lead acid when used beyond 50% DoD. Failing to fully charge lead acid on a daily basis causes additional wear.
if you're comparing solar+batteries to a generator, then you might come out ahead, or not. a standby generator with a full fuel tank won't degrade much if well protected from the weather (both the fuel and the generator). possibly longer than the standby lifetime of a set of lead acid batteries.
The only way to see actual return on investment with batteries is to do a grid-tie with battery backup. this keeps the batteries charged for maximum lifespan, and you sell any surplus generation back to the grid. this gets you UPS grade backup power if done with modern equipment (double-online or standby style), and if you live in a place that does time-of-use or event priced power, you can switch to battery for load shaving whenever the price point makes sense.
Long-term testing of solar panels shows them to have 80% or better output after 20+ years of use. that seems pretty solid.
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American Locomotive
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Your figure is pretending that no power will be used from the grid during the day, and that the battery is only going to last the minimum amount of time, and that the battery is going to be fully discharged every single time. A good deep cycle lead acid battery will last thousands of cycles if only partially discharged - up to 5,000 cycles or more for certain gel-cell type batteries.
If you want to cherry-pick data, then the 10,000+ short-cycle life of NiCd would be the real kicker. having a pack big enough to do useful work running a shop while lasting 5k cycles is one hell of a battery pack. Even the people I know who are off-grid and have banks made of trojan forklift batteries only have a few days of power in the winter at most - if they conserve. you can equalize a bank of forklift batteries easily and not suffer thanks to being able to water them - you have to take apart your battery bank and charge cell by cell to equalize a gel pack. it's not at all practical for this sort of use.
most people don't have a battery pack big enough to draw down power at the 20 hour rate - the 4 hour rate is more likely, and that gives you 80% discharge efficiency added on to the 80% charge efficiency. assuming for the sake of argument you charge from a 1200W array, your net available power from the array is effectively reduced to about 750W. if you were charging from the grid, you'd be paying 40% extra for power.
if you want a battery bank of AGM or gel batteries big enough to get a 5k cycle life out like you can out of an x kWh li-ion pack, you need to limit DoD to 70%, and then upsize the lead acid pack to 2.5x kWh for the same usable storage. wanting 10kWh of stored power but having to buy 25kWh of storage to get it is not economically viable.
http://www.batterypoweronline.com/wp-content/uploads/2012/07/Lead-acid-white-paper.pdf
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HOTFR8
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Granted they are not cheap but you would be compliant. So what about the other option I stated having your Solar stand alone so it is separate from your grid system?
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TheEquineFencer
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TheEquineFencer
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I had no idea this thread would go so far off...If the MOD would, please delete it before I get banned.
Free batteries turns the numbers on their heads. makes things way more economical. Btw those Li-ion prices are out of date in the article i linked above - numbers are from 2010 or older. they're much cheaper per kWh now.
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TheEquineFencer
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HOTFR8
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Not if you designed it to carry the load you require. For example my small stand alone system has two 80 watt panels two 6 volt batteries and an invertor.
It runs my computer (includes printer, scanner, router and modem), phones, fax, answer machine and also has a few lights on the system as well. To back it up I have a battery tender plugged into the mains power. I have a power inlet on the wall with a short lead from the invertor to that plug and the office has its own power points all on the dedicated system. To do it properly in any way you need to spend some money so it works as it should.
The risk you have with the switch would be cooking batteries when the power is not being used from them and it is isolated.
I see no reason for you to be banned.
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