We have a few towers that are pure solar powered and do not use inverters (we will define an inverter as a device that takes battery voltage and current to make high voltage AC similar to mains AC. We acknowledgethat buck/boost converters are a form of inverter but generally have no isolation between input and output and do not generate high voltages) anywhere.
Do not take this as a “how you should do it”, your setup is different with different requirements. This is how we do it and now that we have a reliable, repeatable and expandable system method, this is how we are doing all of our towers. The only differences being the source supply, if AC is available then we step it down and rectify using a constant voltage power supply and a reverse current diode, if no AC the we plan for solar PV and design the capacity to the tower plans. A stub tower will not have anywhere near the capacity of a hub tower, but both will always be designed to never exceed a depth of discharge of more than 50% under normal operating conditions.
Everything is directly battery powered or uses a buck/boost converter as needed. No relays between sources, just charge the battery and it will power everything.
We use Packetflux sync injectors (there are two: Canopy, the old style and Cambium, the new style. They look identical but the timing of the Cambium style is compatible with cmm5 while the Canopy style is compatible with cmm3). We also use a Packetflux Site Monitor to provide system monitoring of battery voltage, current flow, cabinet security, solar panel anti-theft security loops, solar voltage, cabinet temperature, etc all pulled by SNMP to MRTG/Cacti (running both side by side now).
We use Cisco switches (internal reasons) but they are 12vdc on the inside so we modify them for our needs.
We have a few different solar controller/chargers, but the one we recommend is the Midnite Classic. Depending on your needs, solar PV max current and battery voltage, you can choose the one that best fits your needs. For us the Classic 150 was the only choice due to the battery size (500AH @24v) and the solar array current (we can hit 70A!). We also set our panels to face east, south and west in smaller directional arrays. This is to maximize the number of charging hours in winter (our shortest day in winter is just under 7hrs) and also to ensure that we can get off the batteries as soon as possible in the morning. Having the panels directionalized reduces total charge current but increases hourse of charge so the trade-off is worth it since that batteries can only take so much at once and time on charge is a major factor in battery cycle longevity.
We do have one site that we are planning to add a 300w wind turbine alongside the solar PV system to reduce the PV requirements (limited size due to specific local regulations) and due to the area being in wind farm central, this will also reduce discharge time on the batteries which means smaller AH ratings needed. But we are also facing winds that can exceed 30m/s (no thats not a typo!) So finding an affordable turbine that can handle 15-20m/s average, start speeds as low as 2m/s and will self-retard in winds as strong as 30m/s is not easy (I am looking for suggestions if any).
We also have small 1200w gasoline powered generators that we can take to any of our towers to provide charging just in case we get some bad weather that makes normal charging impossible. This gives us just short of 40A of current at our 24v (28.96 charging voltage) battery voltage so about 30A of charging or about 8hrs to recover an average tower battery.