General questions on SolArk with batteries and generator

[darkskies]

Just for my education, can anyone who is familiar with SolArk help describe how it works in a on-grid configuration, with batteries and a generator, when the grid fails?

Without the grid available, once the batteries deplete, I'm assuming the generator kicks in?

Will the generator charge the batteries, as well as provide power for the house load?

At what point would the system switch back to running off batteries? Is this some configurable set point?

I was browsing the web-site and couldn't seem to figure out how the SolArk works in this configuration (sent email to SolArk a few weeks ago, but haven't heard anything).

Thanks in advance for any info here.


Just FYI. I have a SolarEdge system with batteries, backup interface, and generator, but the generator is not integrated into the system as was advertised with the backup interface. SolarEdge has been telling me to wait for a firmware update, but after 1.5 years, with the firmware finally updated, it still does not seem to be integrated (working with my installer). If it will not work as designed, I need to discuss option with my installer, who did mention at one time that they also install SolArk systems. I'm trying to learn more about SolArk, in case it comes to that (although it's a big change and I'm not sure if the installer will really go that far)

 

[629658]

So you are correct. As a matter of fact we just had a 3 hour outage a few nights ago. At 0230-0530. Almost missed it if the dog hadn’t gotten me up. Neighbor dark we weren’t. We were not out long enough for my gen set to kick in. So we are on battery since the sun goes down. When the grid went down no difference to normal. Had our SOC dropped to 30% then our generator would automatically start and both the house loads and the charger would be on the generator. How much depends on your generator size. I have an 18kW so it will handle all the loads and full amperage battery charge. I estimate our run time to 95% SOC to be approximately 2hrs or PV takes over thenn the gen shuts off.

 

[robby]

Just for my education, can anyone who is familiar with SolArk help describe how it works in a on-grid configuration, with batteries and a generator, when the grid fails?

Without the grid available, once the batteries deplete, I'm assuming the generator kicks in?

Yes if you tell it to. Also you can set the battery level point at which it will kick in and go off if you use the Time Of Use Menu (TOU).

Will the generator charge the batteries, as well as provide power for the house load?

Yes if the Generator can handle doing both.

At what point would the system switch back to running off batteries? Is this some configurable set point?

90-95% based on user feedback. You can also limit it to less using TOU.

I was browsing the web-site and couldn't seem to figure out how the SolArk works in this configuration (sent email to SolArk a few weeks ago, but haven't heard anything).

Call Sol-Ark and pick the Sales extension, they will explain anything you need to know.

Thanks in advance for any info here.


Just FYI. I have a SolarEdge system with batteries, backup interface, and generator, but the generator is not integrated into the system as was advertised with the backup interface. SolarEdge has been telling me to wait for a firmware update, but after 1.5 years, with the firmware finally updated, it still does not seem to be integrated (working with my installer). If it will not work as designed, I need to discuss option with my installer, who did mention at one time that they also install SolArk systems. I'm trying to learn more about SolArk, in case it comes to that (although it's a big change and I'm not sure if the installer will really go that far)

 

[629658]

Yes if you tell it to. Also you can set the battery level point at which it will kick in and go off if you use the Time Of Use Menu (TOU).

Yes if the Generator can handle doing both.

90-95% based on user feedback. You can also limit it to less using TOU.

Call Sol-Ark and pick the Sales extension, they will explain anything you need to know.

Robby I was in another thread and someone there stated the Sol Ark losses are 4% charge (that is correct I think) and another 3.5% battery to AC. Is that right? I couldn’t find that 3.5% number anywhere.

 

[2TrevorJ]

Robby I was in another thread and someone there stated the Sol Ark losses are 4% charge (that is correct I think) and another 3.5% battery to AC. Is that right? I couldn’t find that 3.5% number anywhere.

https://www.sol-ark.com/wp-content/uploads/15K-2P_SpecSheet.pdf

96.5% CEC Efficiency

 

[darkskies]

Thanks @jfpetesn and @Robbie! Send like a logical expectation on operation of the unit.

I was thinking that it would be beneficial to have the generator recharge the batteries, thinking that it would save on propane, if they use of batteries is extended, and that the power from batteries would be cleaner than from the generator.

Are either or both of those assumptions reasonable?

Someone mentioned that the generator consumption would be load based, so there wouldn’t be an advantage to recharging the batteries (w.r.t propane consumption).

I was wondering thoughts from those who actually are doing that.

In my situation, at this time of year, consumption is about 31 kWh per day. Power consumption runs from just under 1kw up to a peak of 3.1 kw (via monitoring, which samples every 5 mins). My battery is 16 kWh and generator is 10 kw. Via PV (DC) my battery charges from 20% to 90% in about 3 hours in the morning(7:45-10:45am), and that is on top of the house load being powered and the panels not at peak output. Just watching the real time numbers, it looks like the battery is getting almost 5kw applied as the best case.

If I’m calculating correctly, the generator would have to produce 21 kWh to charge the battery (2 load, 5 battery for 3 hours). That would give usable battery off 12kwh so at 2kwh load, I’d get 9 hours run time (3 during charging, plus 12/2 on battery).

Versus generator producing 18 kWh for the same time period of 9 hours.

Am I calculating correctly?

 

[629658]

Thanks @jfpetesn and @Robbie! Send like a logical expectation on operation of the unit.

I was thinking that it would be beneficial to have the generator recharge the batteries, thinking that it would save on propane, if they use of batteries is extended, and that the power from batteries would be cleaner than from the generator.

Are either or both of those assumptions reasonable?

Someone mentioned that the generator consumption would be load based, so there wouldn’t be an advantage to recharging the batteries (w.r.t propane consumption).

I was wondering thoughts from those who actually are doing that.

In my situation, at this time of year, consumption is about 31 kWh per day. Power consumption runs from just under 1kw up to a peak of 3.1 kw (via monitoring, which samples every 5 mins). My battery is 16 kWh and generator is 10 kw. Via PV (DC) my battery charges from 20% to 90% in about 3 hours in the morning(7:45-10:45am), and that is on top of the house load being powered and the panels not at peak output. Just watching the real time numbers, it looks like the battery is getting almost 5kw applied as the best case.

If I’m calculating correctly, the generator would have to produce 21 kWh to charge the battery (2 load, 5 battery for 3 hours). That would give usable battery off 12kwh so at 2kwh load, I’d get 9 hours run time (3 during charging, plus 12/2 on battery).

Versus generator producing 18 kWh for the same time period of 9 hours.

Am I calculating correctly?

I think you’re close. Yes the Sol Ark will save propane. We run on propane and before the Sol Ark in a grid down situation our generator would auto start and run until power restored. I could manually stop the gen to save LP. I estimate our gen consumption at 3-3.5 gal/hr. So I have on-site 114 hrs (5 days) of propane if our tank is full. With the Sol Ark I’m looking at needing 2-4 hrs per day of gen time depending on PV or cloudy. So around 40 days of fuel.

I would suggest additional battery storage. I have about 45 kWh (928 aH). And really need another 22 kWh of storage.

 

[darkskies]

Wow! That is a pretty high consumption rate. I looked up the 10kw Generac that I have. It looks like consumption is 0.97 gal/hour at 50% load and 1.48 gal/hour at 100% load for LP.

 

[629658]

Wow! That is a pretty high consumption rate. I looked up the 10kw Generac that I have. It looks like consumption is 0.97 gal/hour at 50% load and 1.48 gal/hour at 100% load for LP.

Yes we live rural now. When we first bought it we lived where natural gas was present. But at the end of the day the Sol Ark allows us to go 40-50 days with our tank. Realistically probably 35-40 depending on the time of year but more than that it works and works well. It’s seemless. It replaced a grid tied inverter and we love the additional independence it provides.

 

[darkskies]

If I calculate correctly, using my math from above…

Generator only @ 2kw/h for 9 hours (0.97 gals/5kw*2kw) is about 3.5 gals.

With 7kw/h to drive house and battery for 3 hours and then getting 6 hours from battery @ 2kw/h the usage is between 3.1 (1.48 gal/10kw*7kw * 3 hrs) and 4 gals (0.97 gals/5kw*7kw * 3 hrs).

I guess the savings depends on how much more efficient the generator is at 70% vs 50% load. Assuming I’m accounting for things and calculating correctly.

 

[tve]

I have a 10 year old Generac 16kW genset. For L.P. the specs say:
25% load: 1.2 gal/hr
50% load: 1.6 gal/hr
75% load: 2.1 gal/hr
100% load: 2.4 gal/hr
I've read that idle is almost the same as 25% load. 25% load is 4kW, that's perhaps 3x our "house idle" load. So yes, charging batteries at 50%+ load and then turning the genset off saves a lot of L.P.!