EcoRenovator  

Go Back   EcoRenovator > Improvements > Solar Power
Advanced Search
 


Blog Register 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 11-04-13, 07:15 PM   #1
djimm100
Lurking Renovator
 
Join Date: Nov 2013
Location: Los Angeles
Posts: 1
Thanks: 0
Thanked 0 Times in 0 Posts
Default DIY Interactive grid tie-in with battery back-up

Hi all.
I want to install a pv system with battery back-up that works during a power outage. I understand that the pv power is routed to an inverter that transfers power to either the main breaker panel (and the grid) or to a critical load subpanel that bypasses the main in the event of a power outage. I understand that the wiring to the main is via a breaker, but do not understand how to connect the subpanel to the house circuits. Do I just pigtail the wires to the appropriate circuits sometime after they leave the main panel's breakers?
Thanks ahead of time.

djimm100 is offline   Reply With Quote
Old 11-05-13, 07:19 AM   #2
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,322
Thanks: 359
Thanked 585 Times in 490 Posts
Send a message via Yahoo to jeff5may
Default

There are many different systems and ways to do this. The main questions here are: how big, how simple, how long. Your skill level and wallet/budget also have a lot to do with the end result.

How big? Are you planning on using 1 panel or 100? 10 watts or 10 kilowatts?

How simple? Some systems are prepackaged, pretested plug and play type rigs. Others are completely DIY in nature.

How long? Do you want to provide backup power to a few small devices for up to an hour, or the whole house overnight?

Some small grid-tie setups plug straight into an outlet like a refrigerator or clothes dryer, whereas most larger rigs have their own circuit wired into the main box. The type and complexity of the system, as well as local power company policies, dictate most of the details here. Prior planning prevents poor performance in a big way here.
jeff5may is offline   Reply With Quote
Old 11-05-13, 10:50 AM   #3
stevehull
Steve Hull
 
Join Date: Dec 2012
Location: hilly, tree covered Arcadia, OK USA
Posts: 829
Thanks: 241
Thanked 164 Times in 122 Posts
Default

This got me thinking of a concept that may have some validity; short term battery backup only for peak hours.

With the rapid introduction of smart meters, it is easy to adjust your consumption, but what about the family with two kids, all coming home and dinner needs to be prepared. But this is just at the time of peak power . . .

Perhaps a small backup of batteries to get you through this peak power period. Many of us realize the math of using batteries to compete for grid power is not cost appropriate. But this is at $0.10/kWhr.

The equation completely changes when power is at $0.50/kWhr (or more).

May have gone off topic, but this combination of interactive grid with battery backup may have a lot of financial utility.

Thoughts?

Steve
__________________
consulting on geothermal heating/cooling & rational energy use since 1990
stevehull is offline   Reply With Quote
Old 11-05-13, 01:39 PM   #4
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,322
Thanks: 359
Thanked 585 Times in 490 Posts
Send a message via Yahoo to jeff5may
Default

The main goal here is: get what you want without tons of trial and error. Since the local power utility and its unique set of rules, codes, and pricing structure are set in stone (today) for us private citizens, it's best to start your quest there. They may help or resist your desire to go solar. They may or may not have hoops you must jump through to qualify for whatever programs or incentives they may or may not have. In this situation it's WAAAY better to ask for permission than forgiveness.
jeff5may is offline   Reply With Quote
Old 11-06-13, 10:45 AM   #5
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,322
Thanks: 359
Thanked 585 Times in 490 Posts
Send a message via Yahoo to jeff5may
Default

Steve,

That's a great idea! This method would also keep your backup battery bank from developing memory. Sooner or later, the price of everything always goes up... the best time to buy something durable is now, give or take a price adjustment. Your dollar is always going to be worth less in five years.

Djimm,

I've found a webpage that describes the type of system you inquired about. Literally jam-packed with examples, pictures, pricing, and lots of pertinent reading.

Emergency Solar Backup Power, AC Coupling, Home Generator Kits

The main difference between a standard, grid-tied system and what you ask about is what happens when you have a power outage. With a standard grid-tied system, the panels automatically shut down when utility power is lost. This is done to protect firemen, electrical linemen, and other workers from being electrocuted by your solar panels. A permit is nearly always required to tie anything to the utility lines that can generate its own power to ensure the safety and ability to disconnect the secondary source of power.

With a Backup system, the utility lines are disconnected from the solar generator the same way, with a plainly recognizable "smart" disconnect for safety, but part of the system remains energized. The back-up power generation/batteries/inverter can be rigged different ways, with different components, for different needs or modes of operation. The main idea is: do your homework and get the right components that will operate how you want them to. Cuz they tend to be expensive and sensitive.
jeff5may is offline   Reply With Quote
Old 11-06-13, 05:42 PM   #6
NiHaoMike
Supreme EcoRenovator
 
NiHaoMike's Avatar
 
Join Date: Oct 2008
Location: Austin, TX
Posts: 1,107
Thanks: 15
Thanked 243 Times in 229 Posts
Default

You can make a cheap grid interactive (not grid tie) inverter out of an old rackmount UPS (must be an old double conversion type and not a newer high rail or delta conversion type). Simply connect the solar panels to the battery through a charge controller and plug the loads into the UPS. The loads will have battery backup and will be powered off the solar when it it available, off the grid otherwise. Excess solar power would be wasted so have a controller bring extra loads online under that condition.
__________________
To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...
NiHaoMike is offline   Reply With Quote
The Following 2 Users Say Thank You to NiHaoMike For This Useful Post:
Daox (11-07-13), Ryland (11-07-13)
Old 11-07-13, 08:06 AM   #7
Ryland
Master EcoRenovator
 
Join Date: Mar 2009
Location: Western Wisconsin.
Posts: 913
Thanks: 127
Thanked 82 Times in 71 Posts
Default

I grew up with a battery bank in the house, my parents still have battery back up, I would never go the route of whole house battery back up unless you regularly have multi day power outages, not just one every 10 years.
The route that I would go is the UPS (uninterrupted power supply) it's a box of batteries, charger and inverter that you plug in to the wall outlet and you plug your device in to this box, when the power goes out the batteries take over, you can wire in as many batteries as you want to make it last as long as you want but the thing is, you are not sizing it to power your whole house, you are using it to power your fridge and maybe you plug an LED light in to it too or your internet router if that is something that you can not live without.

Whole house battery back up systems are the most expensive and the highest maintenance systems you can install and most people, after 10-15 years have let their batteries die, realize that they never used them and wasted a lot of money on them.
Ryland is offline   Reply With Quote
The Following User Says Thank You to Ryland For This Useful Post:
Daox (11-07-13)
Old 11-07-13, 09:27 AM   #8
stevehull
Steve Hull
 
Join Date: Dec 2012
Location: hilly, tree covered Arcadia, OK USA
Posts: 829
Thanks: 241
Thanked 164 Times in 122 Posts
Default

Ryland,

I think we all agree that whole house battery backup is not economical. A friend of this forum (and mine) that sells internal combustion back-up is now convinced that the combination of using grid tie solar PV AND a small generator is the way to go. But he is biased as he sells generators . . .

He feels that using off peak power to supply the house (often at 1/2 the average rate) is a great way to cut the electricity bill for some 20 hours per day. The problem is that life can interfere with minimal use of electricity during times of peak power (4-8 PM typically). This is also just the time when PV sun exposure is waning . . .

I found this to be so while caring for an adult parent on an oxygen concentrator . . . .

Question: Does the group feel that battery back-up or a small generator is the best way to go to provide the need for power in this time niche?

At this peak time billing period, you are competing with the cost of peak power of $0.40- 0.60 per kWhr and even higher in large metropolitan areas ($1 and up). So we are NOT competing with power at $0.10/kWhr or so.

Steve

__________________
consulting on geothermal heating/cooling & rational energy use since 1990

Last edited by stevehull; 11-07-13 at 12:37 PM..
stevehull is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 12:46 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design