Station Backup Power & Solar Powering your station

Basic Battery back up

• Simple and Automatic• Requires true Deep Cycle batteries• Isolates the battery and power supply with

diodes• Set the power supply to the appropriate voltage

for the battery using a DVM• Radio runs off power supply when grid is

present and flawlessly transitions to battery on grid failure

Basic Battery back up

Solar Powering the Radios (or other loads)

• Step 1 is to calculate the loads daily usage. • Using Watts is usually the best way• Amps times Volts = Watts• Watts times hours per day = Kwh’s• Duty Cycle is important for Radios• Never use the name plate of an appliance

measure it with an accurate meter.• Do not trust the name plate of an appliance use a

quality meter

Solar Powering the Radios (or other loads)

For measuring DC loads a Clamp on amp meter can be useful. These are average priced at sears and other places. With Radios we have to be careful as RF can interfere with Digital Meters.

Analog meters are frequently built into Power supplies and can be close enough for estimating Radio consumption

Solar Powering the Radios (or other loads)

AC Loads are important if you plan to add an Inverter to the system. Shown here is the famous Kill A Watt Meter. Very handy device even if you do not plan on using Renewables. Checks and logs Watts, VA’s etc and also keeps track of time so it logs Kwh’s as well.

Remember the cheapest KWH is the KWH never used. Conservation comes first.

CFL bulbs have a bad Power FactorLEDs are good

Load calculations

Example (Scanner uses .3 amps at 12v or 3.6 watts and I leave it on 24/7 so it uses 86Wh per day)

So lets say I have 4 loads I want to run:*Scanner = 86Wh per day

*2 Meter radio in receive uses 60Wh per day

*LED lights in my shack use 48Wh per day

*HF radio is used 2hrs per day and draws 30 amps when transmitting. I figure a 50% duty cycle so 30Ax2Hx12Vx.5DF so it uses 360Wh per day (Duty Cycle is really important here)

Battery SizingTotal of 554Wh per day or .55Kwh per day now we can size the battery. Typically we size the battery for 3 days of Autonomy and a maximum discharge of 50%

554Wh / 12v = 46Ah (amp hours)

46Ah times 3 days of autonomy is 138Ah

138Ah times 2 for 50% discharge is 272Ah of battery capacity

Solar Panel sizing

Sizing the Solar panels (PV Photovoltaic Panel) we use the Kwh per day value and the daily sun hours. Pvwatts.com is useful for this. So lets assume we get 4hrs of sun a day in Maine

554Wh divided by 4hrs of sun is 138.5 watts of PV needed before losses. We also need to run some loads as well. A 250 watt PV panel would work well here. It would give us a usable average of 1-1.5Kwh per day

Putting it all together

• Solar Panels• Larger wattage is usually cheaper than smaller

wattage. • Smaller wattage is more portable• Voltage is important (VOC Volts Open Circuit) • Consider Mounting of the Solar Panels

Putting it all together

• Battery• Must be true Deep Cycle. If it says anything

about Cold cranking amps it is not deep cycle • FLA (Flooded lead acid) is most common but

gasses when charges• AGM (Absorb Glass Mat) does not gass when

charged but is more expensive and less forgiving of abuse

• Lithium and other chemistrys

Putting it all together

• Charge Controllers and Breakers• Charge Controllers regulate the PV panels to

do a controlled 3 stage charging of the battery• Charge controllers come in 2 styles PWM or

MPPT • Charge controllers are rated in output amps• Voltage is important (VOC Volts Open Circuit)

Putting it all together

• Inverters for AC loads• An Inverter takes the DC from a battery bank

and produces 120VAC or 120/240VAC depending on the Inverter

• Inverters come in Modified Sine Wave and Pure Sine Wave

• Some Inverters have battery chargers • Inverters come in all shapes and sizes

Small 12 volt system

Larger System

Resourceswww.midniteforum.comwww.midnitesolar.comwww.altestore.comhttp://www.windsun.com/

Or

Feel free to get ahold of meryan@kb1uas.com