Solar Backup Generator

[Lizw]

Re: Solar Backup Generator

It depends on the climate of a particular location. In San Francisco, or along most of the northern California, Oregon, or Washington cost, AC is not essential. I couldn't survive in Phoenix in the summer without AC. I'm unfortunately very heat sensitive and get sick with migraines and other nasty things when it gets too warm. I currently live in the Sacramento area (101 outside now) and the AC issue has been on my mind the last couple years. I don't think I could survive here in the summer without AC and it's not nearly as severe a climate as Phoenix. This is probably why most of the areas with lousy climates like Phoenix were very sparsely inhabited until AC became affordable and common.

Yes, exactly. Though when I lived there, it was a haven for people with asthma, whose doctors had sent them out there for the dry air.

To run more than the most modest AC system (like a small room air conditioner) would require a large solar system. Running it off grid would require very large batteries. For example, my 3 ton air conditioner eats about 5 kw when the compressor is running. Running a sustained 5 kw load would require around 100 kwh (such as 48V @ 2000 Ah) of batteries if they are to last 10+ years.

And of course there's the start-up surge. The recent work with capacitors to even that out may help the situation, but absorption units are probably still the way to go in hot humid climates. Or earth-sheltered homes--I have a friend here whose electric bill is almost never more than the minimum, and his home is all-electric. It's also built into a hillside with only two faces exposed.

I put up trellis mounted on 4 x 4's along the western face of the 70 foot mobile home I live in, and grow hops and maypops on the trellis. The vines shade the trailer in the summer and die back in the winter so the sun can hit it (I mounted the trellis panels on hooks so I can take them down in the winter). There's about a ten degree differential between the temperature on the sun side and on the shade side, and that really makes a difference in the amount of a/c we use. Given my druthers, I'd turn the a/c off, open the windows and install a solar-powered ventilation fan in the roof, but it's not my property.

[Zac]

Re: Solar Backup Generator

That's what I thought too, but he said the fault in his system caused the main breaker in his panel to trip.

There is likely a design or installation problem with the equipment if that happens. But, there should be a breaker dedicated to the solar grid tie inverter(s). Shutting that breaker will isolate the solar equipment and allow grid power to be restored by resetting the main breaker.

Only trouble with absorption cooled anything (and I've had plenty of experience with them in refrigerators) is that they're far less fuel-efficient than compressors. But of course if they're solar heated, that's not a concern.

But I'm always amused at the idea that it's not possible to get by without a/c. I lived in Phoenix once, as it happens, in a small travel trailer with no insulation in the late summer, and the heat didn't kill me. Sleeping at night was less comfortable than if we'd had a/c, but we managed. And I spent my teen and young adult years in Florida, also without a/c. The notion that a/c is somehow a basic human need is a relatively recent one.

It depends on the climate of a particular location. In San Francisco, or along most of the northern California, Oregon, or Washington cost, AC is not essential. I couldn't survive in Phoenix in the summer without AC. I'm unfortunately very heat sensitive and get sick with migraines and other nasty things when it gets too warm. I currently live in the Sacramento area (101 outside now) and the AC issue has been on my mind the last couple years. I don't think I could survive here in the summer without AC and it's not nearly as severe a climate as Phoenix. This is probably why most of the areas with lousy climates like Phoenix were very sparsely inhabited until AC became affordable and common.

To run more than the most modest AC system (like a small room air conditioner) would require a large solar system. Running it off grid would require very large batteries. For example, my 3 ton air conditioner eats about 5 kw when the compressor is running. Running a sustained 5 kw load would require around 100 kwh (such as 48V @ 2000 Ah) of batteries if they are to last 10+ years.

[Lizw]

Re: Solar Backup Generator

If your friend has a grid tied solar system, it's failure or shutdown should not make the power go out. That would happen with an off grid system, but not with a grid tied one without batteries.

That's what I thought too, but he said the fault in his system caused the main breaker in his panel to trip.

Air conditioning is the worst power hog and one that is difficult to substitute for, at least until direct absorption fueled air conditioners become common. Absorption fueled air conditioners use heat (from the sun or other source) to drive the heat pump instead of a electrically powered compressor. In areas that cool off at night, more insulation and thermal mass would reduce air conditioning load, but some places like Phoenix, AZ (where it can often be 100 degrees at midnight) are nearly hopeless unless one wants to live underground or in a cave.

Only trouble with absorption cooled anything (and I've had plenty of experience with them in refrigerators) is that they're far less fuel-efficient than compressors. But of course if they're solar heated, that's not a concern.

But I'm always amused at the idea that it's not possible to get by without a/c. I lived in Phoenix once, as it happens, in a small travel trailer with no insulation in the late summer, and the heat didn't kill me. Sleeping at night was less comfortable than if we'd had a/c, but we managed. And I spent my teen and young adult years in Florida, also without a/c. The notion that a/c is somehow a basic human need is a relatively recent one.

[Zac]

Re: Solar Backup Generator

Attached are some quotes for installing a grid tied solar system without batteries in Arizona. That provides an example of the rebate and tax incentives.

The rule of thumb is a solar system mounted at a fixed angle will produced the rated power for about 2.5 hours per day in the winter and 5.0 hours in the summer. (it's perhaps 10% less at high latitudes) Fixed angle mounts can be mounted to optimize for winter production or for maximum annual total production. A steeper angle increases winter production, but decreases summer production. More grid tied applications just use the angle of the existing roof for aesthetics.

[Zac]

Re: Solar Backup Generator

Solar power is a wonderful thing, but it's no substitute for grid power unless you have the money to install a heck of a lot of it, and you can maintain it yourself. I have a friend with a $60,000 grid-tie system he had installed several years ago. His power bill is zero most months, but it will be another five years before the system is fully amortized and his wife won't stay there by herself when he's out of town because something broke one time, the power went out, and she couldn't find anyone to fix it until he got home.

If your friend has a grid tied solar system, it's failure or shutdown should not make the power go out. That would happen with an off grid system, but not with a grid tied one without batteries.

Air conditioning is the worst power hog and one that is difficult to substitute for, at least until direct absorption fueled air conditioners become common. Absorption fueled air conditioners use heat (from the sun or other source) to drive the heat pump instead of a electrically powered compressor. In areas that cool off at night, more insulation and thermal mass would reduce air conditioning load, but some places like Phoenix, AZ (where it can often be 100 degrees at midnight) are nearly hopeless unless one wants to live underground or in a cave.

[Zac]

Re: Solar Backup Generator

well as fast as technology is moving, by the time you measure your roof, figure out how to tie your system into the grid and receive the panels at $1/W, you could be looking at $10,000.

incentives in places like California will pay for the full system.

now, after it is installed, find ways to cut back on your usage so you have excess energy to sell to the power companies as everyone's usage goes up as the electric vehicles start filling the roads and you'll be the winner...

For a 4-6 kw grid tied solar system (without batteries), installed cost after rebates and tax incentives would be $2.50-4.00/watt in most states.

But, keep in a mind a grid tied solar system is not backup power. The typical grid tied inverter shuts down automatically if grid power goes down. Battery storage is necessary for it to provide backup functionality.

[Zac]

Re: Solar Backup Generator

you do understand how many of those it would take to run just your refrigerator don't you? the Coleman will light one 60 W bulb during daylight hours which is figured at 7.5 hours for most areas. A large battery can store that for evening use. most energy efficient refrigerators will need at least 250W each hour, 24 hours a day. so you will need ~32 of those panels just to power your fridge each day. So for a little over $10,000 you can buy enough solar panels to keep your food cold. Now measure your roof to see how many panels you can even put on your home...

If your refrigerator consumes 250 watts on the average, that would be 6 kwh per day (24 hours). That would have to be either an refrigerator of unusual size or a model dating from the 1960s. I have a Maytag 25 cuft refrigerator of 2001 vintage and it consumes slightly under 2 kwh per day. I run that with my small solar system.

[Rocky]

Re: Solar Backup Generator

well as fast as technology is moving, by the time you measure your roof, figure out how to tie your system into the grid and receive the panels at $1/W, you could be looking at $10,000.

incentives in places like California will pay for the full system.

now, after it is installed, find ways to cut back on your usage so you have excess energy to sell to the power companies as everyone's usage goes up as the electric vehicles start filling the roads and you'll be the winner...

[Lizw]

Re: Solar Backup Generator

well very few people understand how much power the new Flat Screen TVs use, but 3 times worse than that are the playstations, just sitting idle they use 3 times the power of most refrigerators.

Good point.

the installed cost of solar panels runs between $7 to $9 per watt, so a 5 kW system would cost on the order of $35,000-$45,000 and an 8 kW system would be anywhere from $56,000 to $72,000.

so for a household using 40-50KW/ day the 8KW system will be enough

So the obvious solution is to figure out how to use a lot less electricity, since an 8kw system is beyond the means of the majority of people.

[Rocky]

Re: Solar Backup Generator

My post was aimed at those who thought 5W would get you anywhere!

(The new Prius is 650V 85KW continuous... putting 4 of the systems I'm working on in the rear storage will be enough to power it.. )

Your system cost for 25KW is less than my system estimate, what's the power source?

gravity

[Rocky]

Re: Solar Backup Generator

well very few people understand how much power the new Flat Screen TVs use, but 3 times worse than that are the playstations, just sitting idle they use 3 times the power of most refrigerators.

Over the next few years, pure electric vehicles will start straining our grids.

imagine what will happen to your energy bill if you start using 40 KW to charge your battery each night...

since I posted my comment I had a chance to do some surfing to find how cheap solar solutions are getting and there are several companies coming out with panels that will cost $1 / watt plus installation and grid tie. So the $1000 / KW is almost here.

Currently the costs are at...

the installed cost of solar panels runs between $7 to $9 per watt, so a 5 kW system would cost on the order of $35,000-$45,000 and an 8 kW system would be anywhere from $56,000 to $72,000.

so for a household using 40-50KW/ day the 8KW system will be enough

[Lizw]

Re: Solar Backup Generator

My post was aimed at those who thought 5W would get you anywhere!
BTW, you can run a chest freezer for 100W 6 hours a day and then use reusable ice blocks to keep your refrigerated food cold in thick walled styrofoam shipping boxes for days, rotating a portion of the ice packs daily. I have tested this out during a 2 week power outage and it worked quite well.
I am looking at 3KW solar plus serious hot water system (most effective use of the sun).

We did that as well, for an extended period, when the refrigerator died. We'd still be doing it, except that my grandson moved in with us for a while and his mother insisted that we had to have a "real" refrigerator.

I'm on the road a lot, and since my housemate is on medication that has to be refrigerated, and a diet that doesn't lend itself to fast food, we carry a big cooler packed with food and several of the "blue ice" packs. I've put a package of hamburger in between two of those packs in the morning, and found it frozen when we arrived at the hotel at night. They work very very well, and I've seriously considered selling the refrigerator and going back to using just the cooler and ice packs at home.

[Lizw]

Re: Solar Backup Generator

you do understand how many of those it would take to run just your refrigerator don't you? the Coleman will light one 60 W bulb during daylight hours which is figured at 7.5 hours for most areas. A large battery can store that for evening use. most energy efficient refrigerators will need at least 250W each hour, 24 hours a day. so you will need ~32 of those panels just to power your fridge each day. So for a little over $10,000 you can buy enough solar panels to keep your food cold. Now measure your roof to see how many panels you can even put on your home...

For those of you who are very serious about powering your home in an emergency power shut down, get out your power bill take your monthly usage and divide it by 30 days... that is the number you will need

One of the projects I am working on right now is a 25KW power generator for homes that including the power grid tie will cost around $20,000.. That will power up to 8-12 homes in your neighborhood...

wish me luck, I'm getting a lot of resistance moving it forward.

The first step for anyone wanting to use solar power is to take a hard look, as you say, at how much power you're using right now. The second step is to ask oneself how much of that power is really needed.

Is an 18 cu. ft. fridge with an icemaker in the door really necessary? Do you have to have a tv in every room (and turned on all the time)? Do you keep the air conditioning at 68 degrees in the summer and the heat at 72 degrees in the winter (a poll found that many Americans run their a/c colder in the summer than where they set the heat in the winter).

Does every appliance in your kitchen have a digital clock? When you turn out the lights at night do you see dozens of little red eyes around the house (power-consuming LED's on every kind of electrical device)?

Do most people know that even when you turn off a tv or computer, it still uses electricity? If you walked around your house in the evening, would you find the lights on in every room?

Solar power is a wonderful thing, but it's no substitute for grid power unless you have the money to install a heck of a lot of it, and you can maintain it yourself. I have a friend with a $60,000 grid-tie system he had installed several years ago. His power bill is zero most months, but it will be another five years before the system is fully amortized and his wife won't stay there by herself when he's out of town because something broke one time, the power went out, and she couldn't find anyone to fix it until he got home.

The bottom line is that people in the so-called developed countries use many times as much electricity as they really need to. If everyone would even just get rid of all their phantom loads, two things would happen. First, electric bills would drop drastically, and second, we'd need a lot less oil and coal to generate the electricity we'd still be using. If a few additional simple steps were taken, more people could convert to solar power because their electrical usage would be within the capacity of a modestly sized solar system.

[Flufreak]

Re: Solar Backup Generator

My post was aimed at those who thought 5W would get you anywhere!
BTW, you can run a chest freezer for 100W 6 hours a day and then use reusable ice blocks to keep your refrigerated food cold in thick walled styrofoam shipping boxes for days, rotating a portion of the ice packs daily. I have tested this out during a 2 week power outage and it worked quite well.
I am looking at 3KW solar plus serious hot water system (most effective use of the sun).
Your system cost for 25KW is less than my system estimate, what's the power source?

[Rocky]

Re: Solar Backup Generator

you do understand how many of those it would take to run just your refrigerator don't you? the Coleman will light one 60 W bulb during daylight hours which is figured at 7.5 hours for most areas. A large battery can store that for evening use. most energy efficient refrigerators will need at least 250W each hour, 24 hours a day. so you will need ~32 of those panels just to power your fridge each day. So for a little over $10,000 you can buy enough solar panels to keep your food cold. Now measure your roof to see how many panels you can even put on your home...

For those of you who are very serious about powering your home in an emergency power shut down, get out your power bill take your monthly usage and divide it by 30 days... Divide that by 24 hours in the day and then multiply it by 3.2, (the total number of hours your panels will be in the sun is ~ 1/3 of the day) - that is the number you will need to power your home with Solar.

One of the projects I am working on right now is a 25KW power generator for homes that including the power grid tie will cost around $20,000.. That will power 12+ homes in your neighborhood...

wish me luck, I'm getting a lot of resistance moving it forward because it doesn't burn fuel.