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Size a dedicated comms battery and solar charger

Comms must outlast everything else. Give radios, alert receivers and satellite gear their own battery and solar panel so they keep running even if the main power system fails.

How

1. List every comms device with its transmit, receive and standby draw from the manual.
2. For handhelds and base radios, use the industry duty cycle of 5 percent transmit, 5 percent receive and 90 percent standby described by Hytera, then adjust for how you really use them.
3. Enter the figures in the comms battery and solar calculator to get daily watt-hours, days of runtime and the panel size needed.
4. Size the battery for the days of autonomy you want. Penn State's sizing method shows critical loads need many more days of storage than ordinary loads.
5. Ask the power designer to put this battery on its own protected circuit, as in safety-18.
6. Match the battery voltage to the radios: 12 V nominal suits most mobile and base radios.

Safety: Fuse every battery lead close to the battery. Lithium batteries need a battery management system.

Do these first

• power-1
• safety-18

Sources

1. Two-way radios and battery life. Hytera Europe (manufacturer), accessed 2026-11
2. Stand-alone system sizing (AE 868). Penn State University, accessed 2026-11
3. PVWatts Version 5 Manual (archived copy). NREL, accessed 2026-11

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