A Forum run by Enthusiasts of MidNite Solar

General Category => General Discussion => Topic started by: sirmoiu on June 29, 2013, 06:15:33 PM

Title: grid tie with battery backup
Post by: sirmoiu on June 29, 2013, 06:15:33 PM
Hi everyone, I have a question that I hope that can be answered, when is the best or energy efficient time to go on your battery, during day while the batteries are charging or at night. Thanks
Title: Re: grid tie with battery backup
Post by: Robin on June 29, 2013, 06:40:56 PM
What is the intent? do you want to reduce your electricity bill by running on batteries?
If so, it is usually hard to beat the power company's prices. Replacing batteries is expensive. In either case, if you want to run off of batteries, you will need to shut down when the batteries reach a certain level. That level is usually adjustable. If you have a grid tie battery based inverter, you will be selling back all you can during the day. The batteries are charged. If you take the house or part of it off grid at night, you will have to wait the next morning until the batteries are charged again. These inverters cannot invert to run your house and charge at the same time. You have to make a choice.
Again, what is your goal?
Title: Re: grid tie with battery backup
Post by: sirmoiu on June 29, 2013, 10:27:57 PM
My intention is to reduce my power bill, and yes I have two 2kw grid tie battery base inverters that automatically switches between on grid and off grid, it switches to grid tie when the batteries reaches 45 per cent, and when sun rises it switches over to off grid, it can also be manually switched over, and we do not sell power back to the power company here in the Bahamas, our power consumption is reduced.
Title: Re: grid tie with battery backup
Post by: Westbranch on June 29, 2013, 11:43:28 PM
Just to clarify that is 45% SoC under load...  can you tell us what the loads are? and what the battery rating is?
Title: Re: grid tie with battery backup
Post by: sirmoiu on June 30, 2013, 11:21:51 AM
Ok, I have 10-150w panels total 1500kw, the 45 per cent is the battery voltage, the batteries are 4-200 ah 12 volts connected in series 48 volts total, the inverters are 2kw each. I hope that helps.
Title: Re: grid tie with battery backup
Post by: phonetic on July 01, 2013, 05:30:51 AM
Keep in mind battery cycle costs 10-20 cents per kWh, its really not cost effective to use nitetime tariff to charge batteries. for using power during day ?
Title: Re: grid tie with battery backup
Post by: sirmoiu on July 01, 2013, 09:28:20 AM
Thanks everyone for the good suggestions
Title: Re: grid tie with battery backup
Post by: ananthapriya on July 26, 2013, 02:01:13 PM
Oh god! how do i answer this question hmm yeah mostly for  Until now, gridtie solar power systems operated only when utility power was available. When the grid went down, the electricity from your solar panels was not used. Now, specialized inverters from Outback Power enable your gridtied solar panels to charge a battery bank from which you can power your home.and also  When the grid is running properly, your home or business will use power generated from your solar panels or pull electricity from the grid. Any excess power generated over and above your needs go back to your utility company for credits on your power bill in areas where net-metering is available.
!!!!!!!!!!!!!!!!!!!!!!This is the fact! you got your answer.
Title: Re: grid tie with battery backup
Post by: Halfcrazy on July 26, 2013, 03:21:38 PM
Actually battery based grid tie has been around for a good long time and Trace Engineering has been doing it for many many years. Outback is just one of the many manufacturers to make a battery based grid tie inverter. SMA and Schneider are a couple more.

Take a look here: http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=30&productCatName=Inverter%20Systems,%20Pre%20Wired%20-%20Grid%20Tie%20with%20Battery%20Backup (http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=30&productCatName=Inverter%20Systems,%20Pre%20Wired%20-%20Grid%20Tie%20with%20Battery%20Backup)

Ryan
Title: Re: grid tie with battery backup
Post by: mtdoc on July 26, 2013, 04:24:09 PM
Ryan,

Why did you discontinue the prewired Outback epanels?
Title: Re: grid tie with battery backup
Post by: vtmaps on August 04, 2013, 08:05:39 PM
Quote from: mtdoc on July 26, 2013, 04:24:09 PM
Why did you discontinue the prewired Outback epanels?

I would also like to know.  I have recommended them to several newbies over at the NAWS forum, as well as to friends here in Vermont.

BTW, the June/July issue of Home Power has a Midnite advertisement for prewired Outback systems.

--vtMaps