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<blockquote data-quote="Noobie" data-source="post: 3046638" data-attributes="member: 127485"><p>OK I am going to weigh in here to maybe dispel a bit of misconceptions, please don't take offense.</p><p>A modified sine wave inverter takes DC current and makes a stair step square wave shaped AC current. You can typically (don't take my word for it) run most computers on this because the computer power supply just converts it back to DC for use.</p><p>Typical AC motors for such things as well pumps, freezers etc. will eventually burn out if run on modified sine wave inverters. Most of them require a capacitor to start because switching from N to S and back generates no torque, there needs to be a phase difference between the coils. These capacitors suck up an enormous amount of current on startup, then they are switched off. Thus you will typically need double the nameplate power to start them. True sine wave inverters require a lot of electronics to make them work. A typical generator naturally makes sine waves which is nice. BTW those capacitors can store a lot of high voltage, and typically have a resistor that 'bleeds' them down after awhile. Best advice is to short them out before touching the terminals or you are in for a nasty and possibly fatal shock, especially if the resistor connection fails. You will see them bolted onto or near the motor.</p><p>One thing to consider is that after a power outage of more than a day or two, all of your freezers and probably the well pumps etc. are going to want to start at once, so you will need to add them all together and double that to determine the surge current. You will have to probably have an electrician read the nameplate rating because the stupid 'uses only x watts/year' rating is because they only run when the freezer gets warm.</p><p>Industrial grade motors such as for milling machines, large pumps, etc. use 3 phase power and require special transformers for the drop to the building from the power lines. Almost no residences use this, they all use single phase. Three phase motors are more efficient by a lot than single phase motors, and by their nature do not need capacitors to start.</p><p>If you have propane, by far the best option is to buy a propane fridge/freezer. They run directly from the propane, have no moving parts, do not require electricity, and are VERY efficient and highly reliable. A typical propane fridge can run well over a week on a standard 20 pound (4 gallon) propane tank. A 500 gallon propane tank holds 400 gallons of propane at max fill, 100 times more than a 20 pound tank. If you need AC electricity for pumps etc. you can get a propane generator. Be aware, however, that a 20 pound (4 gallon) propane tank will only run your generator for half a day or so, just like a gas or diesel generator.</p><p>Systems combining solar, batteries, chargers, inverters, generators, etc. are very complex and expensive and you should find someone or hire someone who really knows what they are doing. Also, there absolutely CANNOT be ANY connection between backup power and the power lines or you will be jailed when a lineman dies...</p><p>One final note is that a 1000 watt solar array is only going to give you 1000 watts on a sunny summer day when the sun is overhead, and you will lose some of that converting and using it.</p></blockquote><p></p>
[QUOTE="Noobie, post: 3046638, member: 127485"] OK I am going to weigh in here to maybe dispel a bit of misconceptions, please don't take offense. A modified sine wave inverter takes DC current and makes a stair step square wave shaped AC current. You can typically (don't take my word for it) run most computers on this because the computer power supply just converts it back to DC for use. Typical AC motors for such things as well pumps, freezers etc. will eventually burn out if run on modified sine wave inverters. Most of them require a capacitor to start because switching from N to S and back generates no torque, there needs to be a phase difference between the coils. These capacitors suck up an enormous amount of current on startup, then they are switched off. Thus you will typically need double the nameplate power to start them. True sine wave inverters require a lot of electronics to make them work. A typical generator naturally makes sine waves which is nice. BTW those capacitors can store a lot of high voltage, and typically have a resistor that 'bleeds' them down after awhile. Best advice is to short them out before touching the terminals or you are in for a nasty and possibly fatal shock, especially if the resistor connection fails. You will see them bolted onto or near the motor. One thing to consider is that after a power outage of more than a day or two, all of your freezers and probably the well pumps etc. are going to want to start at once, so you will need to add them all together and double that to determine the surge current. You will have to probably have an electrician read the nameplate rating because the stupid 'uses only x watts/year' rating is because they only run when the freezer gets warm. Industrial grade motors such as for milling machines, large pumps, etc. use 3 phase power and require special transformers for the drop to the building from the power lines. Almost no residences use this, they all use single phase. Three phase motors are more efficient by a lot than single phase motors, and by their nature do not need capacitors to start. If you have propane, by far the best option is to buy a propane fridge/freezer. They run directly from the propane, have no moving parts, do not require electricity, and are VERY efficient and highly reliable. A typical propane fridge can run well over a week on a standard 20 pound (4 gallon) propane tank. A 500 gallon propane tank holds 400 gallons of propane at max fill, 100 times more than a 20 pound tank. If you need AC electricity for pumps etc. you can get a propane generator. Be aware, however, that a 20 pound (4 gallon) propane tank will only run your generator for half a day or so, just like a gas or diesel generator. Systems combining solar, batteries, chargers, inverters, generators, etc. are very complex and expensive and you should find someone or hire someone who really knows what they are doing. Also, there absolutely CANNOT be ANY connection between backup power and the power lines or you will be jailed when a lineman dies... One final note is that a 1000 watt solar array is only going to give you 1000 watts on a sunny summer day when the sun is overhead, and you will lose some of that converting and using it. [/QUOTE]
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