New With Questions

[sgtgeo]

Hello,

I'm new, just approved yesterday, and I've got questions.

We're in the preliminary stages of getting quotes etc. a grid-tied system.

Like people here have mentioned before we were a bit surprised to find out the array is 100% useless if the grid goes down. I figured we could at least produce power during the day if the grid was down. The protecting the lineman argument is invalid and stupid in my opinion because it's 100% fine to utilize a whole house generator with a transfer switch to isolate the generator from back feeding the grid. The other argument I'm embarrassed to admit I didn't realize at 1st and that is variable output of the panels.

I feel this is glossed over by the install companies when they are all caught up in trying to sell a tax credit. As soon as the questions get hard these guys give up. We actually had a guy come to our house and expected us to sign a contract for a $20K system that day. lol, really? does this happen?

I have no interest in a system that can't help me during a power outage, disaster etc. Power is cheap where I live and we don't use that much, we also get no local incentives and the power company only buys the power back at 33% of what they sell it for.

Enter the hybrid system!!! they want me to buy the StorEdge inverter which is only compatible with 2 SUPER EXPENSIVE batteries LG Chem and Tesla Powerwall (Heard the Powerwall is not even available here)

I have 2 simple question that I hope are simple to answer for the experts on here:

1. If I have a hybrid system using a Solar Edge StorEdge battery ready inverter and I have the $6500 LG Chem battery installed as part of the system will the PV charge the battery while the grid is down (assuming sun etc.)? If not why? Is it also unsafe to charge a battery while the grid is down?

2. Is there another inverter/system that will allow me to use a smaller cheaper battery to mainly stabilize the power delivery. So the grid is down but during the daytime only I'm able to charge the battery at a higher rate than i'm using it so I can essentially run the house off the PV without stability issues. The battery being a buffer for clouds passing over etc.

I feel there is little thought when it comes to grid tied systems and power outages.


I feel the cost of those batteries is outrageous. We don't have more expensive peak rates in the evening or anything that justifies a $6500 battery and $2000 to mount it to the wall and run some wire.

I hope this forum can help because i'm wearing these solar companies out with questions that seem simple to me but apparently no one else has ever asked them.

I guess i'm just supposed to sign, pay, and hope for the best with the 1st set up they quote. Ask for a different panel and they can't get it, but I can buy it online from 10 companies.

Please help!

Thanks

[Mike90250]

Several companies make Hybrid Inverters:
Outback/Radian
Schneider Electric (XW series)
Sunny Island
All work with conventional batteries, but there is a minimum size to support your loads, the batteries have to be able to supply the 120Hz peak surge when generating the sinewave, too small of a battery and it fails.

Going direct from PV you your house wires without a battery, doesn't work so well, because of clouds and starting surges that a simple PV panel cannot support.
One of the major GT inverters has a option for a single medium powered outlet, in case of grid failure, but you have to flip the switch manually.

[ButchDeal]

I have 2 simple question that I hope are simple to answer for the experts on here:

1. If I have a hybrid system using a Solar Edge StorEdge battery ready inverter and I have the $6500 LG Chem battery installed as part of the system will the PV charge the battery while the grid is down (assuming sun etc.)? If not why? Is it also unsafe to charge a battery while the grid is down?

2. Is there another inverter/system that will allow me to use a smaller cheaper battery to mainly stabilize the power delivery. So the grid is down but during the daytime only I'm able to charge the battery at a higher rate than i'm using it so I can essentially run the house off the PV without stability issues. The battery being a buffer for clouds passing over etc.

1) yes

2) as Mike mentioned there are other bimodal invert system but battery size is dictated by the load, battery characteristics, and array size.

I feel there is little thought when it comes to grid tied systems and power outages.

I feel the cost of those batteries is outrageous. We don't have more expensive peak rates in the evening or anything that justifies a $6500 battery and $2000 to mount it to the wall and run some wire.

I hope this forum can help because i'm wearing these solar companies out with questions that seem simple to me but apparently no one else has ever asked them.

I guess i'm just supposed to sign, pay, and hope for the best with the 1st set up they quote. Ask for a different panel and they can't get it, but I can buy it online from 10 companies.

some companies are not very familiar with grid tie bimodal systems.

The cost of the batteries are high, lead acid is cheaper but other inverter systems that can use lead acid batteries are more costly.
If you don't have Time of Use rates why are you considering battery ? if just for backup, how often are the outages? you could get a small automatic generator on the critical loads for less money than the bimodal system. Though with the bimodal system you would get other incentives, like 30% tax credit and possibly a state battery incentive depending on the state you are in.

Also are you sure you don't get net metering where you are located?

[sgtgeo]

Thanks guys,

Our electric company is a small co-op and doesnt offer the best incentives for solar right now. Nearby Duke power has all the incentives. We called and verified with their renewable energy rep exactly what they offer.

I already have a generator that can backfeed and run the house via a panel interlock. But gas, propane, and natural gas will run out or be difficult to get if there is a natural disaster, etc. hopefully the sun keeps coming up.

As far as I know our power has never gone out for more than an hour or 2 in 5 years. I also have insurance on my car I hope to never crash type argument.

system goals:

offset some electrical costs

emergency backup for long term "situation" that hopefully never happens natural disaster or whatever.

Just another layer in our preparedness onion. Lol

[peakbagger]

Thanks guys,

As far as I know our power has never gone out for more than an hour or 2 in 5 years. I also have insurance on my car I hope to never crash type argument.

system goals:

offset some electrical costs

emergency backup for long term "situation" that hopefully never happens natural disaster or whatever.

Just another layer in our preparedness onion. Lol

IMHO your stated goals are the problem. You are mixing two very different goals that have vastly different system requirements and cost implications

"offset some electrical costs" is pretty simple, install a grid tie system built around your utilities incentives and solar policies Batteries are not needed. In some cases that means no system at all if the utility is solar unfriendly. Buy a generator, test and maintain it on occasion and line up a bulk fuel source for the extended outages. If you have natural gas piped to your house and assume its reliable in an emergency, natural gas is the way to go but if you dont the toss up is diesel or propane. Propane is a low maintenance fuel but in an emergency situation, bulk supplies disappear quickly and even gas grille bottles disappear. Diesel does not go bad and its bulk energy density is high so you can store a lot of days of power on site and usually diesel is the first fuel to get back into any area after a disaster.

"emergency backup for some long term situation" opens up a much bigger can of worms. If you are going for an end of the world as you know it scenario there is a big initial cost and in the long term repeated big expensive cost to replace batteries. The battery bank needs to be much larger unless you are willing to make lifestyle compromises

There are some interesting "home brew" projects that connect the house to a hybrid or full electric vehicle. In this case the batteries are routinely used for driving to justify the battery costs and on the rare occasion that you do need emergency power you can use them to support the gird isolated mode. Note the very important "home brew" description, no main stream automaker is selling this option. Lots of future hype and PR but not something you can currently buy. Should it become available in the future I dont see it something that can be retrofit easily. The lack of this functionality is probably a good sign that there isn't the demand to justify the costs.

Yes there is at least one company that sells a secure power supply option that offers a very limited power supply directly from solar panels with no batteries if the sun is out. With some creativity you might get two outlets by paying extra for two smaller inverters instead of one big one. If you want some emergency capability at minimal cost its the way to go. Even if you have it you will be in the dark for 1/2 to 2/3rd of the day if the sun is out.

IMHO if you let the end of the world as you know it scenario sway your thinking you will end up doing nothing or getting conned into writing a big check for functionality that you do not need or will use very often and I expect when the batteries eventually die you will let them and not replace them. KISS is good principle and hybrid systems have considerably more parts and adjustments.

[Ampster]

......

All work with conventional batteries, but there is a minimum size to support your loads, the batteries have to be able to supply the 120Hz peak surge when generating the sinewave, too small of a battery and it fails.
.......

The OP is talking about a grid tied system and at least for the Outback offering of Radian and Skybox hybrid inverters they are able to handle the surge loads by using the grid. The Radian can handle more surge than the Skybox but in either case there is more flexibility in sizing the battery packs than in an off grid system.

[J.P.M.]

SGT:

If you don't have net energy metering from your utility, then, at this time, if your lifestyle is remotely close to anything like the average U.S. household, and for most situations and lifestyles, there is not much chance of you getting a practical, much less cost effective residential PV system.

Also, at this time, it's unlikely you will be able to get a combination of PV coupled to a battery system that will meet all of your needs for a few days by itself (off grid) with anything close to cost effectiveness for less than a whole lot of $$.

Factoid: The average household in the U.S. uses about 12,000 kWh/yr. = ~ 33 kWh/day. I have no idea of your usage, but I'd respectfully suggest if you are considering what amounts to a PV/battery system to supply several days of usage to replace down grid power, you find out what your usage is and get a plan for emergency reductions. Reason: The single Tesla or LG battery has maybe 10-13 kWh or useful storage capacity +/- some. At $6,500 or so each, maybe 2 or more than likely 3 batteries, but likely multiple batteries gets expensive if one goal is to supply power off grid for emergencies or at other times for more than a few hours or so. That's in addition to the cost of the PV system.

Yes, there are tax credits/rebates available that may offset a lot of the cost of a single battery. Dirty secret: Most such deals, if available at all, apply to and stop after the first battery. Some homework is necessary to determine your situation with respect to such rebates/tax credits. Read the fine print. Innuendo in advertising is rampant and can easily lead to incorrect inferences and conclusions.

Check your usage and get a contingency plan/estimate for minimum usage requirements in an emergency.

There is a lot of thought to PV during power outages, but up until now it's mostly been about safety for those who might be restoring power while a bunch of distributed PV systems are sending unregulated power to the grid. I think the priorities are 110 % correct, but fixing the entire situation of may well involve systemic changes, and progress in that direction is slow. As Mike writes, some inverters do have some small capabilities ( ~ 1,500 W) when the sun is shining.

Reality is, the marketing of residential PV installation in the U.S. is mostly geared toward grid tied applications where users have net energy metering. That may change in the future, but for now, that makes your application and requirements something of the odd man out. Expect most peddlers to talk up what they sell (grid tied PV), and beat down what they don't (most everything else). Expect a lack of knowledge about either when discussing such things with salespeople. Caveat Emptor.

As other posters have suggested or alluded to, I'd suggest you stay with the ICE generator you have or one that that uses utility provide nat. gas or, if you are a dedicated prepper, diesel or propane, and at least put PV on the back burner until your power provider allows net metering of some sort.

Fossil fuel fired on site electricity generation is, at this time much less expensive and much more reliable than off grid residential PV supplied power.

Respectfully,

[sgtgeo]

I guess I should not have said "Long Term" because that got everyone thinking huge battery capacity etc.

I have have some new questions:

-While someone was early in this thread said the StorEdge converter WILL still be able to charge a compatible battery during a power grid outage there is little mention of this important capability in their literature. Why are they not pushing this feature of the StorEdge LG battery?

-Why is the StorEdge only compatible with 2 batteries?
is it the 400V requirement compared to the more widespread 48V the reason?

-When I said long term I meant a long term solution to have some energy production during the day weather permitting. If I could get 5000w out of a 9kW array with a battery for a good part of the day I could run a fridge/freezer long enough to keep stuff cold make ice etc. keep things charged, whatever. Can a smaller than poweewall size battery buffer the load during daylight production times. The sunny boy inverter is 1500w max on the secure l

LG offers a smaller 400v battery than their poweewall near-equalivent model. I wonder if it's StorEdge worthy.

Thanks

[ButchDeal]

I guess I should not have said "Long Term" because that got everyone thinking huge battery capacity etc.

I have have some new questions:

-While someone was early in this thread said the StorEdge converter WILL still be able to charge a compatible battery during a power grid outage there is little mention of this important capability in their literature. Why are they not pushing this feature of the StorEdge LG battery?

The battery and PV are on the same DC bus so yes the battery can charge from the optimizers as well as from the grid

-Why is the StorEdge only compatible with 2 batteries?
is it the 400V requirement compared to the more widespread 48V the reason?

There are very few 400V batteries (one really as the PowerWall 1 is no longer produced so just the LG Chem RESU10H now.

-When I said long term I meant a long term solution to have some energy production during the day weather permitting. If I could get 5000w out of a 9kW array with a battery for a good part of the day I could run a fridge/freezer long enough to keep stuff cold make ice etc. keep things charged, whatever. Can a smaller than poweewall size battery buffer the load during daylight production times. The sunny boy inverter is 1500w max on the secure l

LG offers a smaller 400v battery than their poweewall near-equalivent model. I wonder if it's StorEdge worthy.

I am a bit confused by the use of long term in your above statement.
The RESU7H is not as common in the US as the RESU10h.

The Sunny boy inverter does not have a battery backup option but a toy "secure power" marketing feature which is 2kw (used to be 1.5kw)
It is really UP TO 2kW and at any time may be only able to spit out a few watts and if the draw is higher it will trip out.

[Sunking]

The Sunny boy inverter does not have a battery backup option but a toy "secure power" marketing feature which is 2kw (used to be 1.5kw)
It is really UP TO 2kW and at any time may be only able to spit out a few watts and if the draw is higher it will trip out.

It still has a Transfer Switch and only provides very little power. Generator is the only way to go.

[Ksnax]

One really easy backup plan for brief outages is a solar generator such as the Goal Zero Yeti. If all you really need to do is keep a refrigerator powered, a Yeti 1000 can do that almost indefinitely with several 100 Watt panels connected to it. If you have a garage door opener, plug that into it full time for a solid backup plan on that.

I've been running my garage freezer off my Yeti inverter 24/7 with just 200 Watts of panels plugged into it along with the AC charger. I'm able to switch it off of the grid connection for 5 hours a day at this time of year without going below 80% charge when the sun isn't shining. When the sun is shining, it stays topped up to 100%.

No, it is NOT the cheapest way to do battery backup, but again, really easy. (Plus I get to take it camping, which is the main reason I bought it.)

[Mike90250]

One really easy backup plan for brief outages is a solar generator such as the Goal Zero Yeti. If all you really need to do is keep a refrigerator powered, a Yeti 1000 can do that almost indefinitely with several 100 Watt panels connected to it. If you have a garage door opener, plug that into it full time for a solid backup plan on that.

For your brief 5 hour outage, you don't need a backup, the fridge will stay cold.

An average fridge consumes about 1.4kwh daily. Several 100w panels cannot possibly keep up after the first 12 hours

I've been running my garage freezer off my Yeti inverter 24/7 with just 200 Watts of panels plugged into it along with the AC charger. I'm able to switch it off of the grid connection for 5 hours a day at this time of year without going below 80% charge when the sun isn't shining. When the sun is shining, it stays topped up to 100%.

Unplug the yeti from the grid for 3 days and see what your fridge does, with 200w of solar. Pretend there was an storm and throw a pile of leaves over half of one of the panels.

No, it is NOT the cheapest way to do battery backup, but again, really easy. (Plus I get to take it camping, which is the main reason I bought it.)

I double dog dare you to honestly report the results

[Ksnax]

Mike, I have run the numbers, and my Yeti 1000 will power my freezer for 18 hours solid at 50Wh (measured over two days) without the solar. So that is 18 additional hours of cold time AFTER the power goes out - guaranteed. This is not SHTF level backup, but certainly safely capable of handling the load during blackouts of up to a day or so without sun. It's probably not a 3-day solution unless the sun shines fully somewhere in the middle. (800W of panels can charge at 650Wh to top off the Yeti 1000 in a little over an hour and a half from dead.)

Most non-disaster blackouts don't last that long however, so it is more than adequate for a freezer.

My solution works for the parameters I stated.

[Mike90250]

OK you lead with a fridge, and now it's a freezer. Freezers take a fair amount less. 50w x 18 hours is 900wh. i suppose that's less than 1,000wh. Still stinks like funny numbers though.

Is a fridge involved here or just the freezer ? 1 yeti or 2 ? (one for each appliance ?)

[Sunking]

One really easy backup plan for brief outages is a solar generator such as the Goal Zero Yeti. If all you really need to do is keep a refrigerator powered, a Yeti 1000 can do that almost indefinitely with several 100 Watt panels connected to it. If you have a garage door opener, plug that into it full time for a solid backup plan on that.

I've been running my garage freezer off my Yeti inverter 24/7 with just 200 Watts of panels plugged into it along with the AC charger. I'm able to switch it off of the grid connection for 5 hours a day at this time of year without going below 80% charge when the sun isn't shining. When the sun is shining, it stays topped up to 100%.

No, it is NOT the cheapest way to do battery backup, but again, really easy. (Plus I get to take it camping, which is the main reason I bought it.)

There is a much better, reliable, and less expensive way to do that. Been around for 60 years.

AC Charger > Battery > Inverter

No solar required.