FWS Johnston Atoll 24V power systemsWhat We have…•2 identical 24V systems that I’m told are 2000 W each. Fig. A.

•eight 24V PV Panels in each system. See product info label in Fig B.

Fig. A. 1 of 2 24V systems

Fig. B. Solar panel labels

Control Panel area

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•3 Pairs of Deep Cycle 12V Deka Brand Batteries MK-8A8D-T, purchased from Interisland Solar in July-10.

• Batteries located in white box below panels

• 3 switches isolate panels, batteries and load.

Fig. C, Battery and control panel layout

Current Jerry-rigged set up to access power

• Panels are currently kept disconnected from batteries except when we monitor the charging of the batteries since there are no controllers.• Power runs from the batteries 50 ft to our bunker along 10 AWG line where it connects through a bus bar• 24V power runs from the battery line to the converter along its 12AWG wire to a converter to change it from 24V to 12V• Another 12 AWG wire carrying 12V It then goes back to another terminal on the bus bar which is connected to a 450W 12V to AC inverter with 12 AWG

wire.• Currently Not enough power flows through the converter/inverter set up to properly charge a 19.5V/4.6A laptop. My best guess is that the converter

drops the amperage down to far because the inverter can handle much higher demands fine when hooked directly up to our 12V batteries. The converter was designed to convert 48 to 24 Volts not necessarily 24 to 12 but it does work that way. I inherited two of these converters with the power systems.

10 AWG Line from batteries

Solar Converter/ (12 AWG wire) 450 W inverter (12 AWG wire)

12V load to 450W inverter24V Line from batteries

Red is 24 V + line in to converter.

White is 12 V + line out of converter

What We NeedI’m an amateur so if anything doesn’t make sense I may just not know what I’m talking

about so if you have other advice I’m all ears.

• Main objective is to be able to access all the power these systems are capable of generating given the components described on the first page.• I believe we’ll need….

– Solar Controllers to replace the Outback MX-60’s that were destroyed. (sounds like the FM-60’s)• We would also need any terminal fittings, or mounting hardware that would be necessary to install them.

• These will be placed in the control box of the battery bank. Power will run from it 50 feet through a 10 AWG wire that is already in place to our main bunker.

– Control Panel/ Bus board for 24V power that can handle 10 or 12 load lines coming off of it.• From within the bunker I would like to be able to access 24V power through a control board/bus bar.• We’ll need spare fuses/breakers if they are needed for the control panel/ bus board.

– 24V to AC Inverter (possibly the Outback FX 25-24)• From the 24V control box/bus bar I would like power to run to an inverter that could handle the entire 2000W load if it was

needed though I don’t anticipate running any combined loads that would go over that.– 100 ft of double stranded marine grade 12 AWG wire

50 ft of 10 AWG line

Bunker

System Layout

24 V to AC inverter

24 V loads

AC loads

24V control panel

Add Solar controllers Here

12 AWG line

What Gauge line to inverter??

12 AWG line

• Satphone• Freezer backup

As mentioned I inherited these two systems and was told to just bring replacement batteries which we did. The system as it currently is set up is what I was able to put together with the materials available on island. I’m hoping more suitable components will allow to realize the full potential of the systems. The systems were originally supporting a USGS seismic station and were designed by a group called Sacred Power out of the South West somewhere. The panels and the framework are all in great shape and have withstood the elements for at least 6 years. The controllers broke down due to electrical current loving ants that also spray acid out of their butts. They’re introduction around a year ago caused significant corrosion on the circuit boards of the Outback controllers . We are working on controlling these ants and hope to have the problem alleviated by the time the new components arrive. This system will be used by the typical field biologists and volunteers who are all lacking in extensive experience with electrical systems so when considering options we will tend to go with ones that require only a more basic level of technical skills though wiring and some programing of the controllers are reasonable enough to expect. Anything we put together should be something that can be explained to an amateur that posses a good dose of common sense and general competence . We would also like to go with proven components vs. new ones that are not yet available or past the testing phase yet that you mentioned over the phone. I’m open to any suggestions or opinions as to what we might need. Right now these are systems that we do not rely on but could eventually become our primary systems if they work out turning our separate smaller systems into backups.

Greatly appreciate any assistance and recommendations you or your staff can make. We are looking for your recommendations and price quotes for the options you have or suggest.

The three smaller systems we purchased from you have been running without a hitch for three weeks now and are looking good.

Please Contact me at

skropidlowski@gmail.com

Cheers,StefanUSFWS Johnston Atoll Expedition leader.