Our Solar Equipped RVs

This article describes our solar equipped RVs. Here’s what we did, why and how well they worked and what would we do now to improve them.

Our solar equipped RVs (VW Kombi)

The first of our solar equipped RVs was a rare 1974 Westfalia VW Kombi. We added a single 80-watt Solarex solar module (that then cost $650!). It charged a 100 Ah lead acid deep cycle battery via a then basic solar regulator and alternator). This powered two 20 watt halogen lights, and a 40 watt Engel fridge. All proved to be mechanically and electrically reliable – despite being used mostly off-road. The electrics and the solar system worked well – but primarily because we travelled during spring and summer – when there was ample sun.

Were we to own it now, we would double the solar capacity and use a so-called MPPT solar regulator. Such regulators ‘juggle’ the incoming volts and amps so as to optimise charging voltage. The gain is about 10%-12%

The battery would be changed to a 110 Ah AGM. This is because they are more rugged. We’d update the fridge as current units are far more electrically efficient. The size would be 50 litres. Sixty litres would be better but takes too much of the limited space. Rather than using frozen food, we’d use freeze-dried. It is more convenient and enables space for more wine!

The Kombi was an excellent vehicle but, as we were then planning to travel extensively off-road and full-time for a year or more, we (reluctantly) sold it.
The 1974 VW Kombi – my wife (Maarit) is the foreground. Pic: solarbooks.com.au 

Our solar equipped RVs (OKA)

Second of our solar equipped RVs was a one-year-old Australian-built OKA. These were specialist ultra-rugged 4WD trucks powered by basic four-cylinder (4-litre) Perkins turbo-diesel engines and made primarily for mining and quarry operations. Ours had been built with a coach type body and had been used to carry miners deep into the working areas. We had the original roof removed and installed a custom-made pop-top roof. The interior was designed such as to keep weight to the absolute minimum. We used white powder-coated aluminium and spruce timber.

The OKA in camp in the Kakadu National Park. Pic: solarbooks.com.au

The entire interior weighed under 100 kg. Keeping that weight low enabled the OKA to carry 400 litres each of water and diesel. Despite that mass of liquids the completed vehicle weighed 5.2 tonne. Most converted OKAs weight well over 6 tonne. We needed that fuel range as we were to travel Australia’s truly off-road dirt tracks – where, in one instance, there was no fuel for over 2000 km. It also enabled us to refuel in areas where fuel was cheap.

The OKA crossing a crocodile-infested river near the tip of Cape York) – the dome on the roof is the satellite antenna. Pic: rvbooks.com.au

We installed a 120-watt solar module and upgraded to a Bosch 140 amp alternator. These amply powered our (then) huge Westinghouse satellite telephone (it was the size of a large suitcase and weighed about 15 kg!) and dome antenna plus water pumping and halogen lighting.

We drove the OKA over 150,000 km mostly on Australian dirt roads. This included over twelve return trips from our-then home in Broome, to and from the east coast via various routes – that mainly included Alice Springs.

OKA reliability

The OKA was the third of our solar-equipped RVs and proved ultra-reliable. It was a wonderful machine for our then needs – but far too big for city use. It was sold in 2006. Despite that all OKAs are now over 20 years old, most now fetch huge prices –  over A$100,000. Many have been refitted with larger engines.

Apart from replacing the original ten halogen globes by LEDs, there is little we would have changed. The huge satellite telephone stayed with the vehicle when sold – but was by then far larger than needed. Still big ( but hand-held) satellites units were by then readily available.

Our solar equipped RVs (Nissan PatroI)

The third of our solar equipped RVs was a new (2005) 4.2 litre TD Nissan Patrol -the last such to be made. As with the OKA, they were ultra-rugged and totally reliable. We used the Patrol to tow our also-new 2005 TVan – a part camper trailer/part mini-caravan made by Track Trailer for off-road use – it weighed about 1150 kg when loaded.

The Nissan Patrol and TVan wading a river-crossing – on the road to Mitchell Falls (Kimberley, West Australia). Pic: solarbooks.com.au

We used this rig experimentally to trial the concept of having two independent but connectable solar systems (one in the Nissan Patrol, the other in the TVan). The Nissan had a single 120 watt solar module (plus alternator if needed) that powered a 60 litre Engel fridge – handy for shopping. The battery was a 110 Ah AGM. We also used the rig to field trial the very first Redarc Battery Management System (BMS 1215). Clamped rigidly to a steel crash barrier it worked faultlessly for over three years. (Ten years later it controls our solar powered fountain and garden lighting!). The 60 litre Engel fridge was in the Nissan.

Our solar equipped RVs (TVan)

The TVan had a single 60-watt solar module plus a Plasmatronic PL20 solar regulator charging a 110 amp hour AGM battery. This powered our two PCs, three LED lights and a 12 volt electric blanket. The systems could be interconnected if found necessary – but we never found a need to do so. A major benefit of this arrangement is that it enabled the TVan to remain in the shade whilst camping, and the Nissan in the sun. It was used for three across-Australia and back trips.

The concept of two separate (but connectable) solar systems exceeded our own expectations. I thoroughly recommend it. All worked superbly. There is little (if anything) we would change except for more solar on the Nissan Patrol if we lived and/or travelled where there was less-reliable sun. All are fully described in my book Solar That Really Works!


Of our three solar equipped RVs, we experienced zero mechanical or electrical issues. This is remarkable as almost driving was over dirt tracks. It included 24 trips across the 1000 km Tanami track plus over 20 times along the plus 700 km Gibb River Road.

Caravan and motorhome electrics generally are covered in our book of that name – Caravan and Motorhome Electrics