During normal operations, the droplet publishes buffered messages including non-measurement data (events/alerts/droplet_info/device_info/http_over_mqtt/etc) and measurement data.
Non-measurement data are published much less frequently than measurements and therefore shouldn’t make a significant difference to the data used over 4G.
By default. a droplet currently has the maximum number of buffered messages set at 1 000 000 which corresponds to approximately 3-4 months of measurement data, or slightly less due to the non-measurement data.
When the droplet exclusively communicates back to the cloud through 4G network, the amount of data used will closely follow the number of metrics it publishes.
| Number of metrics | Storage usage per month of buffered data |
| 46 ('average' droplet, see below) | ~400MB |
| 80 | ~1GB |
Note that the number of metrics published per site can varies significantly, there are production sites with <20 metrics and ones with >200. The test below was done with 46 metrics per message which is likely close to the average.
As examples:
Fronius PV (Onslow, reduced metrics): 17
Single phase Fronius Primo Hybrid (Mark Sykes): 31
Sungrow Hybrid (Origin): 34
SMA SB + SMA SBS + SMA meter (Origin): 47
Sonnen Hybrid + Fronius Hybrid + Fronius power meter (Marc’s Place): 52
Eguana (Grant, Lochmann): 81 - 95
SolarEdge daisy chain (Yurika Domain): 238
Typically, a 1Gb data plan suffices to cover the data published by a droplet to the cloud.
If your droplet also acts as a gateway to provide internet to your inverter, the total amount of 4G is likely to increase by 2 to 3 Gb per month.