Slide On: Power
It's a game changer
What a game changer. Solar power has almost redefined camping. No longer is there the need for noisy and smelly generators.... except of course if the sun ain't shining they can still be a good back up, or you need to run your air conditioner.... camping? But generally, for the most, you can live with just your solar power system. With the right amount of solar panels to suit your load, you can literally be off grid for as long as your supplies of food and water allow.
How much power is enough?
Even for a lot of caravaners, and certainly camper trailers, I would suspect the demand for powered sites would be lessening. With gas cooking and heating, the main demand for electric power is a the fridge. Lights, now all low power LED, require minimal power. Your typical upright fridge will only consume on average under 2 amps. Over an eighteen hour no solar charging period, that's 36AH (ampere current hours) out of a typical 120A battery... leaving about two thirds full. So, during your 6 hours of prime sunlight time, you need to make up that lost power as well maintain the power load.... which in this simple model requires about 8AH - or about 100 watts of power over the 6 hours from your solar panels. The bottom line is it works.
More batteries give you a bigger reserve, but you still need to consider the amount of power to replenish the battery. Think of it as a water tank. You drain 2 litres of water from your 120 litre tank on average every hour. Even if you doubled the size of your tank, at some stage you still need enough water in to replace what you've drained. That means, whatever your daily drain, you need to factor the capacity to replace it each day. Or if you drain without replacement over a week, you need a good downfall (or in the case of power a massive recharge) at the end of the week to not only maintain what you are draining each hour, but to replace what you previously drained.
So, how power is enough. As much as you use. If your coffee machine is an essential item, you just need to make sure you have enough solar power to cover it. Maybe a wind turbine as well...? (though they're not really a viable solution)
There are generally 3 types of batteries. Lead acid types as used in cars. These are not recommended for camping because of the toxic fumes when the battery is being charged. AGM batteries are very common for camping purposes. However they are very weighty. The ultimate solution are lithium batteries. Three times more expensive but they will out last an AGM battery, making their return on investment better in the long run.
The basic components of a power system are a DCDC charger, battery and solar panel or solar blanket. The DCDC charger charges your camper battery independent of your car battery. So if your camper battery goes flat, your car battery is untouched remaining available to start your car.
There’s a few solar options here. One is the traditional rigid solar panels. They are the cheapest but also more bulky and heavier to pack, unless mounted on top of the camper. Then there’s the flexible panels. These are generally permanently mounted on top of a camper and are ideal for being fastened to curved surfaces. Then there are the solar blankets. Completely portable allowing you too simply lay them over windscreen or on the ground wherever there’s direct sunlight. The portable panels or the blanket are ideal where the camper is parked in the shade and you need to place the panels in direct sunlight.
Good panels will work even in cloudy days, as long as you can feel the warmth of the sun. So as long as you have access to the sun, you can have power to live day after day and keep the fridge running.
Because your power system is at the heart of your camping success, it pays to know what its doing. there's some good value voltage monitors you can wire across your battery. An app bluetoothed to the device allows you to monitor and log daily battery voltage as well as be warned of any abnormal variations. Another app allows you to monitor total net power usage. This connects to a device that measures the current flow in and out of the battery. You do run the risk of becoming a bit nerdy regularly checking this every day, but then again is it being nerdy regularly monitoring you car fuel gauge. No, another quite essential task really!
An inverter is the next accessory to consider. It converts your 12v battery power to 240V. Generally, at least its main use will be to keep your laptop charged. As long as you can cope without needing your electric toaster, coffee machine or electric kettle, the inverter only needs to be a modest power unit, typically 200-300 watts. The bigger inverters up to 3,000 watts will adequately power these above appliances, but as discussed above, will be at the expense of your battery capacity and the ability of your solar source to replace the power drained. So, keep life simple and you’ll have plenty of power to match.
Now that's stretching the limits. However I have seen cases presented in a caravan where it is doable. It comes down to having enough power in to support the power out of an air conditioner. An average caravan air conditioner unit consumes between 1000 to 2000 watts while running continuously. Starting can consume between 2000 to 3000 watts to get the compressor going. Very roughly speaking that's on average about 100 to 200 AH (compared to our 36AH fridge.) But, if you have the solar capacity, that is half an average house solar install, you're on the way to keeping cool. Keep in mind however, at night you would need a few batteries to keep the system going ....then even more solar power the next day to recharge everything while keeping the air con going. It's a challenge, but one I'm sure will inevitably have a solution down the track.
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