Power has proven a big problem at all recent Source Camps.
This has meant a headache for Organisers & problems for Facilitators & Participants.

Whilst each site will be different, having an agreed blueprint for setting up the power system saves time on site & improves both reliability & functionality.

A good power system design can be used as a training aid during sessions.

Low-power

The best way to reduce overload is to reduce power consumption (which is also Green!).

The rule is: "Spend a little extra money on low-power appliances to save a lot of money on power generation/storage."

The best way to ensure clean stable power to appliances is to run off Batteries - 12V truck batteries are cheap & easily sourced locally (no need for expensive gel batteries for a 10 day camp!).

If batteries are not used then power from either the mains or generator needs to be stablised. This is best done centrally at source rather than through outlet-based protection. However if it's not possible to sufficiently clean the source then protecting outlets with surge-protectors may be the only option.

In addition, it is advisable to bring spare power supplies - especially for key network equipment (switches & wireless APs)

Ideally everything would run off 12V (including lighting), rather than needing to be inefficiently converted to 110/240V using an Inverter.

However some low-power Inverters may be useful for items without appropriate 12V inputs/adapters.

A 12 V distribution network would also negate the need for lots of plug-boards (trailing sockets). This is big win as they're decidedly not rain-proof!

Ensure sufficient plug-boards are available for whichever design is chosen - ideally those which can support multiple plug shapes (such as WonPro's WE-3A6R3-E105). Otherwise bring several adapters.

Batteries

Gel batteries provide the best long-term performance/reliability however for a short-term camp, cheap locally-available truck batteries are fine.

Batteries can be mounted in

• Series (+ linked to -).
  Add up the Voltages, so 2x12V => 24V.
  Ah lifetime as per 1, so 2x 120Ah => 120Ah
• or Parallel (+ linked to +).
  Constant voltage, so 2x12V => 12V.
  Ah lifetime added together, so 2x 120Ah => 240Ah
  

Charging the batteries

Ideally this can be done from the mains supply, as this is likely to be the cheapest source. Where this is not available then ideally a renewable energy source, such as Solar would make for a Greener camp. If this is too expensive (even for rental) then a Generator may be needed.

Generators

Generally generators produce dirty output, which needs proper stabilisation. (some generators come with this facility in-built)

When sizing a generator to match a load, remember that the load is usually measured in Watts, whilst the generator is sized in VA (Volt Amps). A rough approximation to convert between these is: 1 (K)VA = 0.8 (K)W.

Full details for those interested:

• http://www.plexoft.com/SBF/K01.html#KVA
• http://www.apcmedia.com/salestools/SADE-5TNQYF_R0_EN.pdf

Solar

The output from Solar Panels needs to go through a Charge Controller on the way to the batteries.

Mounting angle needs to be set correctly to maximise the charge.

Panels should be kept clean.

Calculations - Sizing

See attached spreadsheet for a tool to size batteries/solar charging for different loads.

One way to reduce power requirements would be if facilitators could agree cross-track when they needed access to PCs & when they were just doing theory, so that it might be possible to reduce the number of computers required.However it would be hard to co-ordinate, especially as the agenda can be flexible to respond to new needs.

ToDo:

• might be worth finding some universal power supplies that have been tested in tough environments and with power surges, and that have simple fuses, and using those for all equipment instead of the power supplies that come with the cheap stuff.