Grid tied solar system.

[North Texas]

I have read most peoples opinions on battery back up systems. I understand the cost factor of not getting your money back. I want solar for the independence not money savings. With that being said. I'm looking at installing a 7kw to 8kw system on my house. The location I'm mounting is straight south with zero shade all day. That will provide 80 to 100% of power year around. I want a battery backup that would provide power for critical loads only. 1 freezer, 1 fridge, living room lights and maybe a couple fans. Trying to figure out usage for that stuff now. I live in tornado alley and as a kid seen power go out for over a month. When it hits a town the grid is down for a while. So is there a way to run a hybrid inverter without battery's until needed. The idea being I can go get battery's after disaster. I don't think this is possible but making sure. Or can I trick a regular inverter with solar DC signal to think the POCO has power (with a cut off from POCO of course) Or is there something I can add after the fact to a another inverter that can make if capable of battery back up? Or should I go with smaller system and do battery back up now. Have about 20k to spend for now (me doing most of install). Would just want a system that can be upgraded easy. Such as just adding more panels and battery's. Don't want to change out major components later. I'm here to learn please teach me!

[solarix]

There are no inverters that you can just add batteries to when the time comes. If they need batteries then, they need batteries now.
You could go with a hybrid type inverter (SMA Island, Schneider XW, Outback Radian) which only needs a relatively small battery as it operates in grid-tie mode until an outage occurs.
Since you are looking at a sizable array, how about 2 (or more) SMA TL inverters that during an outage can change modes with the flick of a switch and generate a limited (1500w each when the sun is shining) amount of power without any batteries at all! A couple of these would run your basic critical needs during the day, keep the fridges cold, charge cell phones, etc.
Plus, could add on the SMA island system later (warning - they are not cheap) to give you real off-grid strength and works with the TL inverter to keep it running as an "island" in a sea of your neighbors that are SOL in an outage.

[ButchDeal]

So is there a way to run a hybrid inverter without battery's until needed. The idea being I can go get battery's after disaster. I don't think this is possible but making sure.
Or can I trick a regular inverter with solar DC signal to think the POCO has power (with a cut off from POCO of course) Or is there something I can add after the fact to a another inverter that can make if capable of battery back up? Or should I go with smaller system and do battery back up now. Have about 20k to spend for now (me doing most of install). Would just want a system that can be upgraded easy. Such as just adding more panels and battery's. Don't want to change out major components later. I'm here to learn please teach me!

No to the first. Hybrid systems need batteries to operate though they just keep them topped off till the grid is down.
On the second sort of, you can get a full hybrid system and us that AC couple a grid tie system but it would need batteries and costs would be even higher.

Solar is not generally easy to upgrade and particularly hybrid / off grid systems are not easy to upgrade.

An OutBack Flexpower 2 would make a perfect fit for you with an 8kw system.

[Mike90250]

Zero out your bill with a grid tie system

Spend your battery money on a generator

If winds take out your local wires, the debris will take out your solar panels (glass, outside, in the wind) and your batteries are flat and you will need to run the generator anyway. Work up a safe fuel storage scheme, there are many ways.

[North Texas]

You could go with a hybrid type inverter (SMA Island, Schneider XW, Outback Radian) which only needs a relatively small battery as it operates in grid-tie mode until an outage occurs.

So i could do this without getting a full battery system ( just one or two batteries?) and add batteries later? Would lack of a full battery bank kill that battery quick?

Since you are looking at a sizable array, how about 2 (or more) SMA TL inverters that during an outage can change modes with the flick of a switch and generate a limited (1500w each when the sun is shining) amount of power without any batteries at all! A couple of these would run your basic critical needs during the day, keep the fridges cold, charge cell phones, etc.

This may be the way to go! I dont care for much power, mainly just for food. I'm not good with math in electricity, does my numbers add up? I thought all grid tied solar systems became usless in a power outage? Is this capable only cause of the inverters?

Plus, could add on the SMA island system later (warning - they are not cheap) to give you real off-grid strength and works with the TL inverter to keep it running as an "island" in a sea of your neighbors that are SOL in an outage.

That is pricey as an add on. May as well do a full battery backup instead of this.

[North Texas]

Zero out your bill with a grid tie system

Plan to as close as I can without going to far over. My POCO net meters but doesn't pay anything for extra electricity.

Spend your battery money on a generator

I already have a small generator that can do what i need. Would just plug them directly into that generator.

If winds take out your local wires, the debris will take out your solar panels (glass, outside, in the wind) and your batteries are flat and you will need to run the generator anyway. Work up a safe fuel storage scheme, there are many ways.

I agree this is a concern. I live on a little bit of land so there would be a little less flying debris but is very likely I loose panels. And if I go with one inverter rather than micro inverters, If I loose one panel in the series, I loose all power from that series? My thinking with having a generator and another source of power is, 3 is 2, 2 is 1, 1 is none.

[North Texas]

On the second sort of, you can get a full hybrid system and us that AC couple a grid tie system but it would need batteries and costs would be even higher.

So this would be just a grid tied battery system?

An OutBack Flexpower 2 would make a perfect fit for you with an 8kw system.

For grid tied only? Or for for grid tied battery back up?

[North Texas]

Usage

Found usage on frig and freezer. Total for both is 89.5 kwh per month, 2.98 kwh per day. Published numbers, am in the middle of measuring with a kill a watt.

[ButchDeal]

For grid tied only? Or for for grid tied battery back up?

Outback is Grid tie battery backup

[DanS26]

Zero out your bill with a grid tie system

Spend your battery money on a generator

If winds take out your local wires, the debris will take out your solar panels (glass, outside, in the wind) and your batteries are flat and you will need to run the generator anyway. Work up a safe fuel storage scheme, there are many ways.

++1...this is good advice.

Instead of spending money on batteries and all of what that entails, just go out and buy a 500 or 1000 gal propane tank and bury it in close proximity to your propane powered generator. You will save enough money to buy a second backup generator and still have months or more of backup power and much cash in your pocket.

After a few years those batteries will be toast as opposed to that LP tank which will probably outlive you.

[North Texas]

Will this work?

So i could do this without getting a full battery system ( just one or two batteries?) and add batteries later? Would lack of a full battery bank kill that battery quick?


This may be the way to go! I dont care for much power, mainly just for food. I'm not good with math in electricity, does my numbers add up? I thought all grid tied solar systems became usless in a power outage? Is this capable only cause of the inverters?

Will the SMA TL inverter thing work for a slow steady output on sunny days without grid? Do I have to have 2? The TL line doesnt seem to start until 7000 Watt. That would be 2 big inverters. Thinking of doing this and propane generator. looking between a 7kwh and and 11 kwh. Have to go up to 11KWH to get 200 amp service I think? What peoples opinions on this?

[ButchDeal]

Will the SMA TL inverter thing work for a slow steady output on sunny days without grid? Do I have to have 2? The TL line doesnt seem to start until 7000 Watt. That would be 2 big inverters. Thinking of doing this and propane generator. looking between a 7kwh and and 11 kwh. Have to go up to 11KWH to get 200 amp service I think? What peoples opinions on this?

it starts at the 3000 up to 7700

http://www.sma-america.com/products/solarinverters/sunny-boy-3000tl-us-3800tl-us-4000tl-us-5000tl-us-6000tl-us-7000tl-us-7700tl-us.html

[North Texas]

Sma tl

Talked to a company that sells the SMA TL inverters and they say that the 1500 watt plug it has wont produce enough for the start power requirements for the fridge or freezer. Any input?

[SunEagle]

Talked to a company that sells the SMA TL inverters and they say that the 1500 watt plug it has wont produce enough for the start power requirements for the fridge or freezer. Any input?

Unfortunately those SMA inverters while are good quality were only designed to provide some "emergency" power for small critical loads. Refrigerators, freezers and even some window AC systems were not on the list when they sized this system.

[inetdog]

Talked to a company that sells the SMA TL inverters and they say that the 1500 watt plug it has wont produce enough for the start power requirements for the fridge or freezer. Any input?

A conventional freezer or refrigerator compressor does have a significant starting surge, and the SMA SPS does not really have surge capability.
If you have a soft starting inverter type compressor (not found in standard units) then you might get away with it. But rather than deliver max current and drop the voltage to match the SPS will simply shut down on overload.