Hoping someone could help...

[gwm1471]

First of all this is my first post, so if my questions seems dumb, then I apologize upfront.
I currently have a Generac generator that is connected to a Generac auto transfer switch with 16 circuits. I bought a friends solar panel setup (his house sold and the new owners did not want the system) which is 20 - 250 watt solar panels that were ground mounted, a SolarEdge SE5000A inverter, charge controller and AGM batteries.
Now, my generator is dying and I don't want to spend $3500 to fix/replace it (from Generac). I was told it may not last through this coming winter or at the very least, not reliable enough to trust. So...I was thinking of setting up the solar panel system and connecting it to the auto transfer switch in place of the generator. My questions are: one, if this can/should be done and two, will the auto transfer switch use the solar power until the batteries are down and automatically switch over to grid power. My thoughts are that maybe I can run my house off of solar and to use the grid for backup. Thanks for any information in advance...

[Ampster]

You would have to have a StoreEdge inverter to use the batteries. Perhaps that is the model of SolarEdge inverter your friend had,although that looks like the model number for a Grid Tie inverter. The best arrangement to get the most out of yuor batteries is the set up the inverter as a Grid tie inverter and if indeed you have a StoreEdge theb find some batteries that work. As far as I know only the LG Chem batteries use DC coupling to work with the StoreEdge. I don't know what your friend used the AGM for. You mentioned that you also have a chargd controller. Do you know the voltage? You probably need more details in terms of model numbers before you can get much more advice.

[NewBostonConst]

I would think (note... saying think...I am not a expert) you could get a inverter for the batteries and hook it into the gen input to the transfer switch. Then also get an AC battery charger that would connect to the grid side of the house power to charge the batteries and have the solar array also hooked up to grid.

This way the batteries would charge when the grid is up and when grid goes down the inverter would switch over to your critical needs circuit. The solar would function as a normal net metering grid tie system.

[peakbagger]

If you want a science experiment than proceed with your experiments but if you need reliable backup power buy a new generator or fix the one you have. The cost and complexity to do what you want will exceed the cost for a generator.

[Paul Land]

If you want a science experiment than proceed with you experiments but if you need reliable backup power buy a new generator or fix the one you have. The cost and complexity to do what you want will exceed the cost for a generator.

20x250PVs that a big experiment

[SunEagle]

20x250PVs that a big experiment

Using those panels on a grid tie system would make sense. But trying to build an automatic emergency power system using batteries instead of a generator is an experiment that will cost you more then replacing that generator.

[J.P.M.]

Not dumb at all. But it does show some solar ignorance. Once you get educated with respect to the potential and limitations of alternate energy and PV in particular, you'll have a better perspective from which to make more informed decisions.

Get the generator fixed/replaced for emergencies. Grid tie the PV if you want but get more informed before you attempt it. If you do, you'll probably still need the genny. Stand alone PV for emergencies isn't worth the hassle/cost, at least not at this time.

[gwm1471]

Thank you all for your input. I bought a 11k generator (used) and replaced my dying one...so that is up and running. Solar...my buddy had a separate panel (some house and workshop circuits) for just the solar/battery setup that is why he had a charge controller so I will install it as he had it set up. At least I am all set for the winter... Thank you all again!

[gjohn]

I have a similar problem i hope someone can answer (for some wired reason, i cant start a new thread). I have Solaredge installed for solar panels and connected to backup power battery (LGChem) with no other back up source like generator. The battery is managed by solaredge for backup. The critical (aka backup) load is currently connected directly to solaredge which results in some of the solar produced to go to power the critical load when solar is producing. As i do not want this to happen (our utility gives credit for what is put back to grid), i came up with the idea of installing an auto-transfer switch to switch to backup power from solaredge-connected battery. Are there any solaredge experts who can confirm i can connect an autotransfer switch on the critical-load panel feed coming from solaredge? I am worried about something that may not be obvious to a non-expert like me (e.g any wait time needed for solaredge to do a power surge to ATS). I have included a detailed diagram below to (see circled area). If it wont work, please tell me why.
Also does anyone have any advice on a good lasting but not too expensive (< $400) ATS or similar gadget (30 Amp or higher) that can work with a battery-based backup setup ?
Thank You for your help.
Joanne

[Ampster]

I don't understand your diagram. You show the SolarEdge being wired directly to the meter. Does it go through a breaker on the main service panel or is it a line side tap?
If I understand your goal, you want to sell all the power generated by your panels to the grid. The easiest way to do that is to find out if there is an internal setting that will do that. Otherwise you would need to define when the transfer would operate. It could be time based or measurement of some output. If you really want to take advantage of TOU rates you may want to run the critical loads on batteries during the entire peak rate period. It would be simple in concept to find a transfer switch that could be triggered by a timer.
A quick Google search found the following:

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.solaredge.com/sites/default/files/storedge_charge_discharge_profile_programming.pdf&ved=2ahUKEwiDrYTavNvmAhXUJzQIHdaXCGEQFjAAegQIARAC&usg=AOvVaw1dNSCRnIQhaxdlfXfLSAuK

I am assuming you have a StorEdge inverter.

[gjohn]

Hi Amster: there are indeed multiple breakers that are not shown for simplicity, so it is not a line-side tap. There is a breaker to protect the grid workers (between Solaredge and meter) as well as between panels and storedge for system shutdown. All of this is installed by a professional electrician but he doesn't know much about the Solaredge system (again, you are correct the StorEdge inverter). The time-based system doesnt make much sense for me over what i proposed because in my drawing the critical load will always be powered by the utility until there is a power outage, in which case the battery kicks in via StoreEdge. I want to minimize the discharge of the battery as well and use it only when there is a power outage (to prolong battery life). So my question is do you see a problem in putting an ATS as shown in the diagram? it would have been great if Storedge had a profile that doesnt send PV power (partially) to critical loads when the grid is on, but we havent found a setting in storedge to make that happen (including from the link you sent - unless i am misunderstanding). I dont mind loosing a tiny amount of PV power to an ATS switch.
thanks
Joanne

[Ampster]

Hi Amster: there are indeed multiple breakers......... The time-based system doesnt make much sense for me over what i proposed because in my drawing the critical load will always be powered by the utility until there is a power outage, in which case the battery kicks in via StoreEdge. I want to minimize the discharge of the battery as well and use it only when there is a power outage (to prolong battery life).

Mathematically and electrically it doesn't make much difference if you power your critical loads from the grid or from solar. Lets assume your inverter is putting out 4kW and your critical loads are 1kW. Your meter will see the difference of 3kW being the Net power generated. If you ran the system for an hour you would get credit for 3kWhrs of electricity. I assume you get credited at the same rate that you pay.

So my question is do you see a problem in putting an ATS as shown in the diagram? it would have been great if Storedge had a profile that doesnt send PV power (partially) to critical loads when the grid is on, but we havent found a setting in storedge to make that happen (including from the link you sent - unless i am misunderstanding). I dont mind loosing a tiny amount of PV power to an ATS switch.
thanks
Joanne

Maybe not a problem but you are not going to change the result by putting in a transfer switch, StorEdge does NOT decide where to send the power because power will flow to the loads behind the meter before any excess is sent to the grid. Physics is what makes that happen. The only way you could see the difference is to install a separate meter. Then the question becomes will your power company let you offset generation on one meter with the load from the other meter. Then mathematically the result will be the same, but electrically the power will be equalized at the nearest transformer or the common connection to those meters.

I know you don't want to use your battery except when needed for backup. However depending on your TOU rates you might be able to improve the return on your investment by programming your inverter to use the battery to ride through the peak rate. Then you would charge the battery at super off peak rates. Two issues will determine if that is economical. One, is the rate differential between peak and the lowest off peak rate. Two, the warranty on your battery. What TOU rates are you signed up for and what type of battery do you have? Does the battery have a warranty, which assumes being used by a StoreEdge Inverter?

[gjohn]

Mathematically and electrically it doesn't make much difference if you power your critical loads from the grid or from solar. Lets assume your inverter is putting out 4kW and your critical loads are 1kW. Your meter will see the difference of 3kW being the Net power generated. If you ran the system for an hour you would get credit for 3kWhrs of electricity. I assume you get credited at the same rate that you pay.

thanks. good point - but the catch is that we live, we get credits also for the TOTAL production of the solar as seen by the utility-issued meter for the next 10 years due to solar promotions, in additions to savings you mentioned above. in your example, the meter sees only 3kW and therofore i get only credit for 3KW-h instead of 4KW-h. The other credit is ofcourse the calculation you did above. Another reason to have the storEdge to not send power to CriticalLoad directly is due to the SENSE monitor, which currently gets confused as the electric flow reverses in the critical-line (when solar over produces) and cannot calculate the total usage correctly. By forcing the current to go via the main panel, sense will see the total used by the house.

[Ampster]

thanks. good point - but the catch is that we live, we get credits also for the TOTAL production of the solar as seen by the utility-issued meter for the next 10 years due to solar promotions, in additions to savings you mentioned above.

The critical phrase is, "...as seen by the utility-issued meter....".

in your example, the meter sees only 3kW and therofore i get only credit for 3KW-h instead of 4KW-h.

Yes that is the physics. You can't change that.

The other credit is ofcourse the calculation you did above. Another reason to have the storEdge to not send power to CriticalLoad directly is due to the SENSE monitor, which currently gets confused as the electric flow reverses in the critical-line (when solar over produces) and cannot calculate the total usage correctly. By forcing the current to go via the main panel, sense will see the total used by the house.

The simple solution is to move the Sense CT. I have mine on the main service entrance. It sees power going in both directions and comes up with a consumption and generation number based on what the Solar sensor is reading. The Sense is only programmed to calculate the consumption by using the two pairs of CTs in that fashion,.

I think you may have some expectations that are not consistent with how this stuff actually works. I also may not understand your rate structure and the mechanism of how you get credit for production. The SolarEdge Inverters I believe are revenue grade so the issue is what kind of meter will your power company accept for that production measurement. If they will accept the SolarEdge production numbers then you would not have to install a separate meter to just measure production. Otherwise there is no work around that I can see. A transfer switch will not effect what your single meter sees.

[gjohn]

yeah - you are not understanding the rate structure, no point in going there in detail as that is not the question at hand. TOTAL solar power is what is sent to meter not net. obviously, that can be done in different ways and the meter needs to see 4Kw coming in and we are good. we also dont have peak-power differentials like in California (we are in MA). I do understand the physics (simple kirchoff's law in this case) thanks for trying to help and your ideas.

Anyone out here who can answer the ATS and solaredge question? - that would be very helpful - calling on all experts. All ideas and perspectives welcome. thanks.