How much does DNO approval cost / is it worth it for my system

Boyceyboy123

Oversizing by up to 2:1 is possible with Solar Edge and some other manufacturers, eg Growatt. Most are 1.5:1. 
2 :1 oversize is the holy grail in this country. If you are working within G98 (ie 3.68kw per phase maximum) then  putting 7.2kw on the roof is fantastic for 2 reasons..
1.   A hybrid inverter can put 3.68 kW into the grid or house, and at the same time put 3.68 kW of DC directly into the battery. This is the whole point of hybrid inverters!
2.   During the winter months, your 7.2 kW array will generate nowhere near this amount, but it will still be twice the amount of a 3.6 kW array. This oversizing has the effect of flattening, the sombrero shaped generation profile, providing much better winter, and tell whether generation whilst clipping some energy during the summer months. The overall annual generation will be very much better.

Reed_Richards

Boyceyboy123 said:

1.   A hybrid inverter can put 3.68 kW into the grid or house, and at the same time put 3.68 kW of DC directly into the battery. This is the whole point of hybrid inverters!

Well it might be able to do that but my hybrid inverter can put 3.68 kW into the grid or house and at the same time put 2.5 kW into the battery.  The 2.5 kW limit is imposed by the inverter, I don't know why.  But the battery may well also have its own limit.

Heedtheadvice

Individual batteries do have their limits but like charg and discharge state levels it is best not to push them for battery life. Several battery systems can comprise a set of individual batteries in parallel. That depends on manufacturer and battery design. As an example the Lithium Pylontech US3000C has a current limit at 70Amps at 48v I.e. a nominal 3.3kW. Stacking batteries extends that significantly by x8 or x16 for those number of batteries in theory !! However the inverter usually provides the technically max output power handling so that and the wiring capability are the practical limiting factors in many cases.

Having lots of (or big) batteries does increase the energy storage capacity. For single phase it is quite in order to supply through a nominal 32A breaker for over 7kW ( Breakers employed in practice ought to by much higher rated  than that to cope with short term higher currents rather than the continuous current). High output inverters are available and some can be operated in parallel too.

As with everything like this costs then rise significantly and the DNO might not accept a high storage/ output power system too.

Careful planning helps making a best value installation.