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How to select best UPS and Solar to be off-grid 24 hour for 2kw

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Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#41

How much advance warning will you get? You need 48 kWh + charge/discharge losses. So if you get 8 hours of sunshine on 100 W per square metre panels you need 48/(8 * 0.1) square metres to charge in one day, that is 60 square metre. Or you can use two months to charge and one square metre of solar panels. More panels charge in less time. Then you need a battery about the size of that in a medium sized electric car if…

The OP needs to hire you.

And maybe you'll accept raw diamonds as a payment?

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#42
post #41

How much advance warning will you get? You need 48 kWh + charge/discharge losses. So if you get 8 hours of sunshine on 100 W per square metre panels you need 48/(8 * 0.1) square metres to charge in one day, that is 60 square metre. Or you can use two months to charge and one square metre of solar panels. More panels charge in less time. Then you need a battery about the size of that in a medium sized electric car if…

The OP needs to hire you. And maybe you'll accept raw diamonds as a payment?

This is in extremely bad taste. What precisely about Africa makes you think anyone has easy access to Diamonds?

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#43
post #41

Earlier quoted context omitted.

The OP needs to hire you. And maybe you'll accept raw diamonds as a payment?

This is in extremely bad taste. What precisely about Africa makes you think anyone has easy access to Diamonds?

Sorry but am missing your point. Where is Africa mentioned?

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#44
post #40

Earlier quoted context omitted.

The claim of 'you'll spend more fuel transporting panels' is a total fantasay "generator that will sip fuel." For this discussion to be usefull, you have to provide some numbers. From generator efficiency I was able to find, you need to consume roughly 1 liter of fuel to create 2 KWh of electricity. Playing around with batteries won't change that. If you look at my calculation above, a single solar panel produces the…

Using battery banks helps quite a bit, as you can use a larger, more efficient generator to charge the banks quickly and can size it perfectly to do so, then shut it off. So you might only be running the generator for 4-5 hrs a day or less. This helps with wear and tear, lets you be more efficient, etc. How efficient you can get depends a lot on the specific battery chemistry (columb efficiency), bank voltage, max ch…

Thank you for the breakdown. I think this is very fair - my assumption from the get-go was that it's a longterm stationary installation.

One thing worth mentioning, in some cases, fuel delivery is a expensive/unreliable, so that can neccesitate eenewables in its own right.

I was looking at installing a system for supplimental power of refrigerators (no batteries), but the project never materialised, so I don't have hands-on experience.

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#45
post #40

Earlier quoted context omitted.

Using battery banks helps quite a bit, as you can use a larger, more efficient generator to charge the banks quickly and can size it perfectly to do so, then shut it off. So you might only be running the generator for 4-5 hrs a day or less. This helps with wear and tear, lets you be more efficient, etc. How efficient you can get depends a lot on the specific battery chemistry (columb efficiency), bank voltage, max ch…

Thank you for the breakdown. I think this is very fair - my assumption from the get-go was that it's a longterm stationary installation. One thing worth mentioning, in some cases, fuel delivery is a expensive/unreliable, so that can neccesitate eenewables in its own right. I was looking at installing a system for supplimental power of refrigerators (no batteries), but the project never materialised, so I don't have h…

No worries, hope it was helpful. It gets more complex for a real world case, as there are a number of factors that need careful balancing - too big a battery bank and it's hard to do the periodic rebalancing you need to keep the bank healthy, as it requires a significant amount of power, but infrequently. Too small a bank and you'll cycle your generator too often (lots of cold starts cause wear). If you never run your generator for very long, it'll probably be dead in a year or two from corrosion or similar issues - some have decent self exercise routines, but for many it's inadequate. Also, it's almost never a consistent predictable load, especially for households. Grid power benefits immensely from law of large numbers - any individual spiky demand someone does blends in when averaged over 100,000+ homes or a city of a million people, so you can predict and size things better. If you're the only user, your usage can swing from 50mw (standby power for something), or even zero mw - all the way to 11kw in the space of half second (welder). Way more orders of magnitude increase, and way faster than the grid will ever have to deal with. You'd need to decide if you'd want to be able to handle that, and if not, what you'd need to handle - and pay up front for the equipment.

It's almost never a problem to have 'too large' an array from an electrical perspective, but from a practical use of land/space and cost (especially when racking, up to code electrical lines, installation) it's really hard to not cut corners there. Most people end up with arrays that are too small in winter, or don't take seasonal insolation variation, shade, or similar problems into account enough.

Part of what has been helping with solar is dirt cheap financing. Even with nearly free panels, if you factor all the other associated costs in (if you're in the US, permitting can be a nightmare for instance), break even can be a decade or more out even with free money. After that it's not so bad though.

Fuel prices and logistics are like you point out a big factor. In my case propane isn't overly expensive and I can get it delivered. Diesel isn't super cheap, but not bad either. If you're paying $10/gal for diesel delivered, or have to go months or more between deliveries of substandard fuel, it changes the equation a lot.

OP never did reply with details did they?

Re: How to select best UPS and Solar to be off-grid 24 hour for 2kw

#46

Earlier quoted context omitted.

This is in extremely bad taste. What precisely about Africa makes you think anyone has easy access to Diamonds?

Sorry but am missing your point. Where is Africa mentioned?

The original questioner mentioned that they live in Africa.
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