Hi,
I’m currently working on sizing my PV system. I have some information about my system (daily consumption, peak consumption on all three phases combined - I’m looking into one phase system for now). But the main problem is the combined inrush current of appliances. I was expecting this so I bought a clamp meter with an “inrush” function and started measuring.
The four primary appliances I would like to power from my system are fridges/freezers.
Two of them have 1,9 kW inrush, third 1,8 kW inrush and the last one 1,5 kW inrush. Before someone points out that I should buy new fridges I would like to say, that one of the fridges with 1,9kW inrush is a three-year-old fridge. If those fridges decide to turn on all at once the inrush is around 7 kW.
Now this is my dilemma. If you take a look at the MPPSolar users manual for PIP5048MKX you get something like this:
Rated Output Power: 5KVA/5KW
Overload Protection: 5s@≥150% load; 10s@110%~150% load; 100ms @ ≥200% load
Surge Capacity: 2* rated power for 5 seconds.
Can those numbers be really trusted? I would prefer real data/information from someone who actually does have this type of inverter and tested its overload/surge capacity. Because the inrush should be measured in the first 100 ms by the specs I should be able to run something with at least 10 kW inrush with this inverter which I really doubt. But maybe I’m wrong.
Now I’m thinking about what to do. I know that the peak power consumption of my whole house was around 7,5 kW (all three phases consumptions combined). So probably 8 kVA MPPSolar inverter would solve this problem but it doesn’t have the double conversion capability (I don’t wanna get fined for illegal export to the grid). Paralleling two 5 kVA MKX takes a toll on power consumption. The 8 and 11 MAX inverters aren’t able to guarantee zero overflows to the grid (also the absence of zero transfer time ATS is a bummer). And on top of that the price of 8kVA MPP isn’t that far from 3 kVA Victron Phoenix which I suspect will last longer in the long run (I know it isn’t really a fair comparison because Phoenix isn’t AIO, but I’m thinking about moving to Victron inverters in the future anyway because of their overload capabilities, lower power consumption, and most likely longer service life). The problem is their steep price. So I was thinking about starting with something cheaper, meanwhile letting the PV system pay for itself and later transfer to Victron. I’m also open to look into some other inverters than Victron but that is the cheapest brand of the “Tier 1” inverters I’ve found. So I’m basically asking for help with what to do about that inrush because the consumption after the inrush stage is under 1 kW from all the fridges/freezers combined and I think it would be a shame not to run them all.
I know that I’m getting a little bit off topic but now I’m thinking about the whole double conversion deal. If I would be able to somehow synchronize off grid inverter with grid I would be happy. Then I would only need to hack together simple ATS. The whole idea behind using this exact inverter is that when there won't be enough energy in batteries the inverter will switch to the mains. I expect this to happen mainly in spring and autumn. You know.. those months when the sun can run your appliances for most of the days but some days it just isn't enough. In this case it would be nice to have the ability to switch automatically to the grid without wasting energy in dual conversion. I was thinking that this would be possible to do with the bypass mode of the inverter but after reading the manual I’m more confused than not.
I’m currently working on sizing my PV system. I have some information about my system (daily consumption, peak consumption on all three phases combined - I’m looking into one phase system for now). But the main problem is the combined inrush current of appliances. I was expecting this so I bought a clamp meter with an “inrush” function and started measuring.
The four primary appliances I would like to power from my system are fridges/freezers.
Two of them have 1,9 kW inrush, third 1,8 kW inrush and the last one 1,5 kW inrush. Before someone points out that I should buy new fridges I would like to say, that one of the fridges with 1,9kW inrush is a three-year-old fridge. If those fridges decide to turn on all at once the inrush is around 7 kW.
Now this is my dilemma. If you take a look at the MPPSolar users manual for PIP5048MKX you get something like this:
Rated Output Power: 5KVA/5KW
Overload Protection: 5s@≥150% load; 10s@110%~150% load; 100ms @ ≥200% load
Surge Capacity: 2* rated power for 5 seconds.
Can those numbers be really trusted? I would prefer real data/information from someone who actually does have this type of inverter and tested its overload/surge capacity. Because the inrush should be measured in the first 100 ms by the specs I should be able to run something with at least 10 kW inrush with this inverter which I really doubt. But maybe I’m wrong.
Now I’m thinking about what to do. I know that the peak power consumption of my whole house was around 7,5 kW (all three phases consumptions combined). So probably 8 kVA MPPSolar inverter would solve this problem but it doesn’t have the double conversion capability (I don’t wanna get fined for illegal export to the grid). Paralleling two 5 kVA MKX takes a toll on power consumption. The 8 and 11 MAX inverters aren’t able to guarantee zero overflows to the grid (also the absence of zero transfer time ATS is a bummer). And on top of that the price of 8kVA MPP isn’t that far from 3 kVA Victron Phoenix which I suspect will last longer in the long run (I know it isn’t really a fair comparison because Phoenix isn’t AIO, but I’m thinking about moving to Victron inverters in the future anyway because of their overload capabilities, lower power consumption, and most likely longer service life). The problem is their steep price. So I was thinking about starting with something cheaper, meanwhile letting the PV system pay for itself and later transfer to Victron. I’m also open to look into some other inverters than Victron but that is the cheapest brand of the “Tier 1” inverters I’ve found. So I’m basically asking for help with what to do about that inrush because the consumption after the inrush stage is under 1 kW from all the fridges/freezers combined and I think it would be a shame not to run them all.
I know that I’m getting a little bit off topic but now I’m thinking about the whole double conversion deal. If I would be able to somehow synchronize off grid inverter with grid I would be happy. Then I would only need to hack together simple ATS. The whole idea behind using this exact inverter is that when there won't be enough energy in batteries the inverter will switch to the mains. I expect this to happen mainly in spring and autumn. You know.. those months when the sun can run your appliances for most of the days but some days it just isn't enough. In this case it would be nice to have the ability to switch automatically to the grid without wasting energy in dual conversion. I was thinking that this would be possible to do with the bypass mode of the inverter but after reading the manual I’m more confused than not.
