I’ve used solar panels on expeditions for many years. They are invaluable when you aren’t near a power source for extended periods. At the compact and portable end of the spectrum the Power Monkey Explorer is a popular lower cost option that combines a solar panel with a detachable battery unit. It is a well-designed product. The panel folds open like a book so the solar units are protected for storage and there is a large range of connector tips available so most things can be covered. Small items like mobile phones or ipods can be plugged directly in to the solar panel or the battery can be charged from the mains and the electrical item plugged into that instead. The Power Monkey works pretty well although I never seem to get the battery or the electrical appliance as fully charged from the panel as I do from the mains and the panel is so small it takes a long time to charge things. It is also only suitable for small low power items and I have had no luck at all with things like a high demand Blackberry smartphone.
Moving on from the Power Monkey I have also dabbled with a panel made by Silva . This is another unit that folds open and is about twice as big as the Power Monkey. The connector is a cigarette lighter socket so anything that comes with this type of connector can be plugged in. Well, I say anything, but really I mean anything that the unit is powerful enough to charge. Trouble with this panel is that it really only charges phones and similar items so for me it wasn’t much of an improvement on the Power Monkey.
As Peak Mountaineering runs more and more commercial expeditions to remote destinations my requirements for a solar system have changed. Nowadays I really benefit from having a laptop with me so I can keep on top of logistics and clients can occasionally watch a movie in the mess tent on long evenings. I also want to be able to charge any camera batteries, the satellite phone and any other devices that clients bring along. It also really helps to be able to run a couple of lights in the mess tent at night otherwise clients end up using head torches.
Some time ago I decided to look at a viable system to handle all these requirements. I was soon in a minefield of information and it was really hard to find a complete system that synchronised well and was user friendly enough for a technophobe like me. After plenty of surfing I’d narrowed the search down to Brunton or Goal Zero. Brunton seem to be very well thought of and their equipment appears to be well made and carefully thought out but I found it tricky to identify which component should go with which and what size panel I’d need to charge a power hungry laptop. Goal zero, on the other hand, had some packages that seemed to synchronise easily and do exactly what I wanted. The only problem was that I couldn’t find a stockist where I could see much of the range for either manufacturer.
Fortunately, my problem was solved when my family visited Anglesey for a cragging weekend. On the campsite there was a large panel fastened to a family tent and as I wandered past I saw it was made by Goal Zero. When I next saw the owner I asked for his thoughts on the system. 2 beers later and I knew far more about any solar system than I’d previously picked up. Tom (the owner) turned out to be a real enthusiast and more than happy to talk me through me his system.
The panel on the roof was a large folding Goal Zero Nomad 27. From the panel a cable ran into his tent and on a small table he had a large battery unit called a Sherpa 120. Above that sat a small invertor (to allow charging of 110 or 240V items) and connected to the battery a cable snaked up to the roof of his tent where a couple of smart looking lights were waiting for darkness. It was a simple looking system and just the kind of thing I’d been looking for.
But how did it perform? Well Tom lost me a bit with his explanations of amps and watts but the upshot of his information was that, in his opinion, the system worked like a charm. The Nomad 27 can produce 27 watts of power which can charge the battery in about 8 hours in bright sunshine. It even works fairly well in overcast conditions although it obviously takes longer to charge. The unit folds into 8 smaller panels that then fold into a small laptop size package. A small connecting unit allows the panel to be connected to the battery or electrical items to be connected directly to the battery via a USB socket (care needs to be taken not to damage the electrical appliance if this option is taken). Several of the same panel type can be connected together if more power is needed. It’s a simple system.
The solar panel connects very simply to the Sherpa 120 battery which generates 120 watt hours of power. This means that if, for example, an item drawing 3 watts is plugged in the Sherpa will run it for 40 hours. The outputs from the battery are a cigarette lighter socket (connector supplied) or a O.5 amp USB socket. This allows plenty of small items to be plugged straight in but some modern items draw more than the 0.5 amp socket can supply (my Blackberry, for example, throws up an error sign if I plug it into the USB port). The third part of the package is an invertor that sits on top of the battery and plugs easily into the back. This is by far the best feature of the system as it allows mains items to be plugged directly in and I have no problem charging a small netbook or laptop, smart phone, sat phone and lots of other expedition devices.
Goal Zero also do a couple of lights that are tailor made for this system. The Light a Life units are stylishly designed 3 watt lights that have become my lights of choice for lighting mess tents and camping areas. They come with a simple plug in connector and a long cable with a useful carabiner style clip at the light end so they can be hung easily from most places. If you need more units they can be connected directly to each other. The lamps are a bit vulnerable to damage so I tend to store them in a large Lock and Lock food container. More importantly, they are also very bright and one light can easily light a 15 person mess tent.
Goal Zero also make a smaller light unit called the Estrella. It’s far more compact but I have heard they don’t give as good a light output. Truth is, I can’t say too much as I haven’t used them but they might be on my shopping list for the future!
Now clients on our expeditions don’t have to use head torches in the mess tent and they have the facility to charge camera batteries or similar items. It also means we’ve always got plenty of back up power for our sat phone, GPS or emergency mobile. Rechargeable torch batteries, camera batteries, portable speakers and just about anything else is chargeable. And of course, there’s the environmental benefit. I no longer have to pack a stash of alkaline batteries as we can take rechargeables and solar power is none polluting and free.
Of course that free energy comes at an initial cost. Retail prices for the complete system come in at around £600 – a weighty investment by anyone’s standards. The system is also quite heavy. Take all the items and you are looking at a weight of 4kg. I use it for either car camping or on expeditions where equipment is carried but you certainly wouldn’t want to go back packing with it. They are also, despite being very durably made, prone to damage if they are being carted around in duffle bags or strapped to Sherpa’s or mules. I have found some very well sized Eagle Creek padded cases that could have been purpose made for the battery and invertor. The search for a protective case for the panel goes on but it’s survived everything that’s been thrown at it so far.
I understand that Goal Zero are revamping several items in their range and the Sherpa 120 is due to be replaced (not sure about the Nomad panels) later this year. I have been completely happy with my system but, if they improve even a little on this great product, I can’t wait to see what they develop next!