It all started with a really good idea. Lets reduce our impact on the environment by using Solar Panels on our trip around Australia. Not only would we save money we would also reduce our green house emissions. Well that was the plan anyway....
After visiting numerous forums and local Solar specialist stores seeking advice we came up with the following list for our needs.
- To start with we already had an existing Deep Cycle Dual Battery setup for the camper trailer. These batteries were each 100 AMP hour batteries.
- We also had an in built battery charger that could re-charge those batteries from a 240volt power connection either at home or at a caravan park.
- Next we needed to work out how much Power in AMPS we were likely to consume on a daily basis. To do this you need to refer the various manuals and available information regarding all the electrical devices you are going to use.
In our case the list included
Electrical Device | Amps/Hour | Hours used/Day | Amps used/Day |
| Waeco 80L Fridge | 3 | 24 | 72 |
| 12V Water Pump | 0.25 | 1 | 0.25 |
| 12V Lights | 0.25 | 5 | 1.25 |
| 240V Lights | 0.5 | 4 | 2 |
| Laptop Computers | 1.5 | 3 | 4.5 |
| Kids Games Devices | 1 | 3 | 3 |
| Total | 83 |
Testing.... where the Saga really begins
In some testing of the battery bank life without Solar panels we found that the power was sufficient to run the fridge for a period of 3 days. Which was consistent with the expected usage per day of the fridge and the number of Amps available in the battery bank (ie 200Amps).
After alot of discussion with various experts we had the following calculations regarding the sizing of the Solar Panels that would be needed...
Option 1 - 120Watt panel (cost $500, weight 15 kg)
Output around 7 Amps/hour in full sun. Assuming that you get around 5 - 7 hours of direct sunlight per day onto the panels then that equates to around 50 Amps of power being directed back to the batteries. With this setup over a period of 4 - 5 days the battery bank would still be exhausted as the Amps provided each day were not enough to completely re-charge the batteries and replace what had been used. Basically each day we would have about a 45 Amp difference not being charged to the batteries and by the 5th day this would render the battery bank pretty useless
Option 2 - 240Watt panel (cost $1200, weight 25kg)
Output around 14 Amps/h in full sun. Assuming that you get around 5 - 7 hours of direct sunlight per day onto the panels then that equates to around 90 Amps of power being directed back to the batteries. With this setup each day if the direct sunlight is available the daily usage is covered by input from the Solar Panels and we would be essentially self sufficient for power
Comparison
Option 1 - didn't provide for a self sufficient power source, but was lighter and less expensive. The weight and storage of the Solar Panels were important to us as they needed to stored on top of our camper during transit and then pulled done at setup
Option 2 - provided the required daily power input, but the weight and size would make it difficult to move around.
Our Decision....
Even though the advice we received indicated that Option 1 would not supply the power input required to keep the battery bank sufficient charged.....We decided to trial a 120 Watt panel, basically due to the weight and cost factors of the larger model. In hindsight this was the wrong decision.
Over a number of weeks we continued to trial the 120 Watt panel and in each case it was not able to sufficiently charge the battery bank and repeatedly the batteries were exhausted of charge. In the end we realised that the advice we received was pretty accurate and that the only way we could expect to use Solar Panels to power our batteries would be to upgrade to the bigger unit. Due to the cost and weight for that larger unit we decided not to upgrade and solve our power needs via a Generator instead.
It was an interesting investigation but a wasted effort in the end. I think until Solar technology is more efficient and effective in converting the sun to power then the weight, cost and size of the units will not be suitable for the power needs of camping setups like ours. Other campers are likely to have smaller fridges than ours and the smaller Solar panels might be the solution...
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