Flakey Grid available in remote area - how to build system to get off it

Lake_Man

Hi all,

New here, first post. WOW! What a forum! This place is amazing. Been sitting reading this site ever since i found it a few days ago - really need to put it away and go do some work. One quickly sees that this forum is full of VERY knowledgeable people. I've browsed a few other sites/forums to do with solar but NONE as good as this. Well Done!

BB.

Re: Flakey Grid available in remote area - how to build system to get off it

Welcome to the forum L.M.,

You pretty much understand the basics. Understanding, measuring, defining your loads is the first step.

Breaking your needs up into two systems (at least) would be my first step. System "A" would be for your computers and other communication devices that you want uninterrupted power for... That would be a battery bank + inverter sized for the loads. Depending on your needs, that could be powered with a 500 watt inverter and a few kWH per day. I would suggest a laptop computer--As they are designed to use a minimum amount of power and have their own "UPS" battery backup. Use the grid power to recharge when the grid is up, use solar panels if they are cost effective for your region (lots of sun, can purchase for decent price, won't get damaged, etc.).

For the other loads (large pumps, freezers, etc.)... You have several ways of going. For pumps, short outages are not going to hurt (I would guess). So you could have direct powered from solar (no batteries) when the sun is up, and use diesel gensets or diesel direct to pump/blowers when the power is down and the sun is not shining.

Backing up large industrial pumps/blowers with batteries and inverters is possible. But may be cost prohibitive (battery replacement every 5-20 years, electronics being repaired/replaced every 10+ years, etc.).

A 10 kW load * 12 hours per day on a 48 volt battery bank (hopefully, you can find a large inverter that would run off a much higher voltage bank, but you can get 2x6kW inverters that supply 230 VAC 50Hz single phase for "reasonable" amounts of money (around $6,000-$10,00 USD for 10+kW + shipping). The battery bank, at a minimum, would be:

• 10,000 watts * 12 hours * 1/0.85 inverter efficiency * 1/48 volts * 1 day backup * 1/0.50 maximum daily discharge = 5,882 AH 48 volt battery bank (recommend "forklift" or traction type batteries at a minimum)

And you would need a minimum of 10% charging current (again guessing) or ~588 amps minimum @ 48 volt. That is around a 43 kW charging current (from grid, even a bit more if from solar panels).

Anyway, that is a quick back of the envelope calculation... I don't know what is available equipment/battery wise. And I would suggest looking into the most efficient methods of aeration and moving water. There are some neat pumps that can take AC/DC/Solar Panels/Batteries/etc. for power sources (and a fairly wide range of voltages) which would give you flexibility when looking at options for power.

-Bill

Lake_Man

Re: Flakey Grid available in remote area - how to build system to get off it

This is the 11Kv line that "somehow"got approval..... i will use this as much as this as possible but its a BAD supply - erratic, flakey and VERY unreliable

Attachment not found.

Lake_Man

Re: Flakey Grid available in remote area - how to build system to get off it

This shows the 11Kv line terminating into next doors transformer. The little hut to the left is my outhouse -African Style! Yeah no privacy in there anymore - huge freezer rooms right next to it now. Oh well....paradise lost?

Attachment not found.

Lake_Man

Re: Flakey Grid available in remote area - how to build system to get off it

Hey Bill,

Thanks for your reply.

Lake_Man

Re: Flakey Grid available in remote area - how to build system to get off it

Thanks to this forum found Suncalc - amazing stuff.

Here is my plot and what sun calc tells me the sun does where i am.

Attachment not found.

techntrek

Re: Flakey Grid available in remote area - how to build system to get off it

If you do need a large inverter (mentioned half-way through Bill's post), consider a used UPS if Ebay is an option for you where you live. If you keep your eyes open you can get one for several hundred dollars, used. Units of that size have a very small resell market since companies usually want to buy them new, and most individuals don't want one that big.