Tuesday, February 25, 2025

Thames Solar Electric Boat Review

Something no-one else has done is a review of a Thames Solar Electric boat by someone who has bought one, and owned it for over a year. There are at least ten of these boats on our waterways, but there's never been a detailed review (though there are a couple of very bad reviews on Google and Trustpilot, one of those is ours and the other the first person to ever buy a boat from Thames Solar Electric).

All of the information below is based on our experience of the first three years of ownership, mostly the first year, and all photos and videos were taken by us.

Name: 'Solar 6'
Specification: 65' x 10' fully fitted solar electric widebeam
Price: £192,000 (£184,000 paid, £8,000 withheld due to 'snagging')
Launch date: 29 September, 2021

Solar Electric Propulsion System (SEPS)

This is the much vaunted unique selling point of Thames Solar Electric, so lets see how it stacks up in practice.

Solar Array

The solar array was made up of sixteen 360w panels, wired as two circuits of eight panels side by side, and fixed directly to the roof of the boat with sikaflex. There are two problems with this;

Solar panels are meant to be mounted on "support structures" ¹ so there's an air gap below them to provide "adequate ventilation".
The amount of power you get from an array of panels is determined by the panel generating the least sun. Wiring it up as 2 runs of 8 panels means when either end of the boat is in shade the entire array performance is degraded.

Score: 2/5 (Builder didn't read the manual)

When we reinstalled the panels and our contractors re-wired them they set them up in four banks of four panels, reducing the impact of shade to just four panels instead of eight. Whilst we've not got accurate data on the performance of the panels from before the refit (the inverters didn't provide that), but after the panels were refitted in November 2023 we were off-grid for longer in 2024 than we were in 2021-2023, and we've unplugged from shore power earlier this year, so we think performance has improved.

Battery pack

The batteries are 48 2 volt cells, total capacity 2,000 amp hours. These were housed in the engine bay, sitting directly on the steel floor, with no containment (unless you count a ratchet strap and a piece of wood). Batteries are supposed to be stored in a dry location, within a box or tray to contain acid from a cracked or damaged battery case², otherwise there's a risk of degradation of the steel hull.

We also found the battery shut off switches were under-rated to supply the motors at full capacity, which is one of many electrical faults found in the marine surveyors inspection³.

Score: 2/5 (Builder didn't read the manual, again)

Motors

The main propulsion is provided by two 10kW Lynch electric motors, and a 5.7kW Vetus bow thruster for manoeuvering, both of which are high quality parts. However, after our marine surveyor expressed concerns about the installation of the motors, we asked Lynch (the manufacturer) to do an inspection. They reported that;

the wiring needs to made safe and secure,
the control boxes needed to be properly fixed,
there was no protection over the dashboard (which isn't water proof so the LCD misted up and is unreadable),
there's no thrust bearing fitted,
the final drive is jumping on the lower shaft,
the throttle needs neutral position needs adjusting, and
the motor voltage at full throttle is 39v, it should be closer to 48v (probably caused by the size or pitch of the prop).

Within a year of Lynch visiting our boat they stopped supplying Thames Solar Electric, who now use from Agni Motors (you can see the difference comparing the their website from today and 2022).

The Vetus bow thruster had issues as well, which started within days of getting the boat. Whilst attempting to fix the hot water Thames Solar Electric completely drained the battery running the immersion heater, so we tried to plug in to shore power, but every time we plugged in the mains circuit would trip. After several attempts by Thames Solar Electric to resolve it, an electrician friend (with no boat experience) isolated the cause to the bow section, which turned out to be the wiring for the bow thruster.

The bow thruster is powered by two 12v batteries, in turn charged by a Draper battery charger. The manual⁴ for this charger clearly says ""Do not use the charger in damp or wet conditions" (because it wasn't IP rated), but it had been installed in the forward locker which is not watertight.

This charger didn't have an automatic cut off, which meant the batteries were being constantly charged even when full. Because the negative terminal was loose this caused arcing (the cause of the circuit tripping), and the arcing had partially melted the battery post terminal. We think this also explained why our bedroom lights would glow even when they were turned off.

Bow thruster battery clamp (negative) showing severe signs of continuous arcing due to poor connection/loose terminal. — This is what a terminal looks like after 6 months of continuous arcing due to a loose connection.

Score: 1/5 (Quality parts installed really badly)

Inverters

The inverters supplied were two Voltronic 5kW inverters. We had quite a lot of issues with these, with frequent errors, often displaying error codes which weren't in the manual (always a concern). This might have been down to the quality (these were cheap, with no CE marking) or the installation.

The marine surveyor found the cables and battery switches were under-rated and they were supplied by a single 400-amp fuse, when the manufacturer specifies two 200-amp fuses⁵. The inverters were badly mounted using the wrong screws (which damaged the case) and the cabling showed signs that the wrong tooling had been used.

Score: 2/5 (Cheap parts installed really badly = fire risk)

Heating and plumbing

This was one of the biggest problems we had on the boat. When we stopped for our first night on the boat the hot water didn't work (at all, it was just delivering cold water), this turned out to be the beginning of a series of problems.

'Eco' log burner

The 'Victoria Elegance' (£800 on eBay) was installed with the flue coming out of the top of the stove, turning 90 $°$ , through the wall, then turning 90 $°$ again to a vertical stack.

Image of our wood burner flue with a 90 degree bend. — About half way down you can just about see the flue coming out of the boat and turning 90 $°$

In an attempt to provide air flow and meet regulatory requirements there was a permanently open vent in the wall next to the stove, which meant there was a permanent cold draft in the lounge.

The stove had two big flaws;

Due to the bends in the flue (and despite the vent) there was almost no draw, so whenever we lit the fire we had to open the back door, which on a cold day was not pleasant.
Because of that lack of draw, every time you opened the door to add wood the boat filled with smoke. Everything we owned, everything we wore, stank of smoke. God knows what it did to our lungs.

A comedy side effect of this huge chimney with a 90 $° bend in it was when the wind direction was blowing from the north of south and gusted over 30mph the chimney would blow over! That scared the heck out of us the first time it happened.$

When the fire finally got hot there was a lot of banging, presumably from air in the system. The thermostatic switch installed also turned out to be faulty, when we removed it during the strip out we found there were scorch marks from arcing or shorting.

Score: 1/5 (Cheap parts badly installed)

Under floor heating

By now you won't be surprised to find this never worked.

The design of the underfloor heating (which the builder repeated in at least two other boats, Solar 7 and Solar 10) was flawed (no pun intended).
1. Loose pea shingle isn't a thermal mass (something which stores heat) because a thermal mass has to be dense and unbonded pea shingle is just a load of small stones.
2. Above the hot water pipes was 18mm plywood and 12mm wood veneer flooring, so any heat had to get through 30mm of wood.
Based on testing the floor temperature with the heating on, we don't believe the water ever circulated through the pipes, validated by the temperature reading on the in and out valves which was the same (you'd expect heat loss if there'd been any heat exchange).

Between the log burner and the underfloor heating we had two very cold winters on the boat. The coldest temperature we recorded inside the boat was 6 $°, below the temperature at which you're at risk of hypothermia! 6$

The underfloor hearing during construction showing the pea shingle and pipes. — The 'underfloor heating' under construction in 2021

Score: 1/5 (Learn what a thermal mass is before installing one)

Heat recovery ventilation system (HRVS)

This is supposed to partly warm the fresh air being pulled into the boat using the air pumped out (a heat exchange system). Unfortunately the pipes used were the same as you'd see on the back of a dryer, paper thin with no insulation, so any heat in that air was lost well before it got to the heat exchange⁷.

The HRVS system installed also appeared to be damaged seconds. In the image on the left is what we found when we opened up the HRVS (after six weeks on the boat), on the right is a photo of a new installed unit from the manufacturer for comparison. Doesn't look right, does it?!

Two images of heat recovery systems side by side, one dusty and bent, the other shiny and new. — Spot the difference, one of these is a brand new unit. Guess which one we got.

Thames Solar Electric did fit a replacement when we pointed this out, but the replacement was also badly installed, and never worked. All it did was pump cold air into the boat in winter, so you had a cold draft round your ankles most of the time.

Score: 1/5 (Builder didn't read the manual, again)

Rainwater harvesting

The rainwater harvesting didn't work particularly well. Firstly there was no filtration before the tanks, so the water ran off the roof, through the pipes and directly into the tank. This meant bird droppings, dust and any other debris which fell onto the boat was washed in with the water, and then clogged up the filters (which is what the water is pumped through, on the way to the taps).

Based on a tip from another Thames Solar Electric (unhappy) customer we added fish tank filters to the downholes, which significantly reduced the amount of gunk in the tank.

The second issue was the 1,000 litre water storage tank. Thames Solar Electric bought the wrong tank (an upright tank⁸ rather than that flat tank⁹), so the lid was on the side (which would obviously leak). To fix that Thames Solar Electric had stuck with sikaflex, which worked for almost a year. After the very hot summer of July 2022 the lid started leaking, so from that point on we could only ever fill the tank half way.

Score: 2/5 (The wrong equipment badly installed)

Water treatment plant

The three phase filtration system seemed to work OK, though the filters didn't last as long as we hoped, and the first time we checked them they were really clogged up.

A water filter, a 30cm hollow cylinder covered in black residue — The filters after 10 months of use. The manual says replace after 6 or 12 months depending on water quality!

Once we added the fish tank filters upstream they lasted a bit longer. The water which comes out is lovely and soft when the tank has been filled with rainwater, though because it's quite dry here in Cambridgeshire we have to top it up a lot with mains water from the pontoon taps.

Score: 4/5 (Showing in rainwater is awesome)

Kitchen

Described on the website as a "luxury kitchen", our experience didn't quite match up to that.

Kitchen appliances

We specified the appliances, and they worked OK. It was only when we stripped out the boat that found a number of issues (all hidden from view), some of which an electrician told us were a fire risk.

The cable for the induction hob power was rated for 110v, this was the second highest rated device in the boat after the motors, pulling potentially 7.35kW, and the cable was underspec for power and temperature tolerance.
The induction hob wasn't properly fitted with the minimum clearance to prevent overheating.
The kitchen cupboards were resting directly on top of the fridge and freezer, rather than in a proper frame.
The fridge and freezer were installed with no ventilation and below spec clearance, so they tended to run hot, which explained why they were so noisy.
The wiring was frankly scary (see picture for an example, this is what the oven and hub were connected to).

The power sockets for the oven and hob, badly installed and partly damaged. — The oven and hob switches were wired into this.

Score: 3/5 (Quality parts installed really badly)

Sink and taps

The taps leaked until we realised the fittings hadn't been tightened up at all. After a month we also found the water flow from the kitchen taps was restricted, so we removed the filter and it was full of small stones and what looked like fragments of silocone, which was worrying as it implied the pipes had debris in (the water is filtered from the tanks so any debris would be in the plumbing).

Score: 3/5 (Quality parts installed really badly)

Bathroom

Described as a 'bespoke bathroom', which like the kitchen sounds a lot more impressive than it turned out to be.

Shower

The shower worked for two weeks, but it drained very slowly. Part of the problem may have been that the 24v shower drain pump turned out to be powered by a 12v system, so it ran at half speed. Assuming there was a blockage we used a standard plumbers drain coil to clear it, which perforated the pipe, because rather than standard push-fit waste pipes Thames Solar Electric had used Polypropylene shower waste pipe which is flexible but tends to clog more and perforate easily.

Because of the lack of access, once it was perforated the only way to fix it was to remove the shower tray and door.

Score: 1/5 (The wrong parts badly installed)

Composting toilet

This was a Separett Villa toilet, which came installed with a pump to evacuate the liquid waste directly into the marina. We realised quite quickly that was against the rules (no toilet evacuation into the marina, for obvious reasons!) so we put a 5l bottle in for the liquid waste to drain into and emptied it in the on-site Elsan.

The solid waste goes into a bucket which is mechanically ventilated out of a vent in the side of the boat. This was only 150mm above the waterline, which meant the boat would fail a boat safety inspection because it was sold as a category D vessels, which should be designed to withstand wave height up to 300mm without water entering the vessel[10].

The toilet air exhaust vent dangerously close to the water.

Score: 1/5 (Somehow turned an eco toilet into a risk of sinking)

Infrastructure

This is the 'everything else' category, and was consistent with the rest of the boat.

Exterior and interior paint finish

The exterior paint looked great on arrival, but within a year rust spots started to appear. We're not sure if that was because it was too few coats, or too thin, but we've had to do a lot of rust spot fixing, on areas of the boat which don't experience significant wear.

The interior paint finish was OK, though some doors were missing the final coat when we moved in. It didn't last long, with damp due to thermal transfer on the bow and stern doors causing the paint to flake, mold to grow (within weeks) and eventually the ply peel away from the stern doors and the wood around the bow doors to rot (see below).

A door with glass in showing condensation and mould growing up the corner — The bow doors (in our bedroom) showing condensation from thermal bridging

Score: 2/5 (Looked good but didn't last)

Finished flooring

The floor looked good, but it was uneven in a couple of places. Over time there floor became more uneven, which we realised when we stripped out was because any weight bearing areas (e.g. under heavy appliances or the stove) sunk as the pea shingle was compressed into the kingspan insulation below it.

The biggest example of this was when the floor beneath our bed in the front bedroom dropped by about 25mm. This turned out to be because when the 1,000 litre rainwater reclamation tanks were filled for the first time they crushed the pea shingle into the insulation beneath it.

Score: 3/5 (Looked good but didn't last)

Triple glazing and insulation

The windows are one of the best features of the boat, providing loads of light even in the winter. As with everything else though they turned out not to be quite as advertised. When first one then another window 'blew' (with condensation forming between the panes) we made some enquiries, and found the windows weren't actually triple glazed, they were double-glazed with a third pane added, fixed with sealant, and black tape used to create a tidy exterior finish.

A close up of a window with a hand in view pulling back the edge of black tape.

The 'superior wall and floor insulation' (fitted by the hull builder Aquarius Canal Boat Builders Ltd) was compromised in multiple places, mostly where Thames Solar Electric had cut the foam insulation back and failed to re-seal it.

A section of roof showing cladding, foam and a section of exposed rusty metal — An example of what happens when you expose metal to the warm air in a boat.

On the front and back doors and on the door hatch there was thermal bridging (where metal is exposed on the interior, which then condensates when it comes into contact with warm air inside). We also had multiple damp spots elsewhere in the boat where screws caused thermal transfer and then damp, so the cupboard where our clothes were stored had mold very quickly.

Score: 2/5 (Good initial installation compromised by Thames Solar Electric)

Conclusion

I would not recommend anyone buy a Thames Solar Electric solar electric boat. The hot water, heating and electrical installation was not fit for purpose, the boat failed to meet Thames Solar Electric's claim that "Once you’ve bought the boat, all your energy is free" (a claim which is still on their website today). As our marine surveyor reported;

"The level of workmanship in all areas including electrical, plumbing, joinery and general fit-out is that of someone without the requisite skills, experience and understanding".

It's a shame that the end product was so poor as many of the components (the motors, the toilet, the appliances) were high quality, but the cheap inverters, wood burner and the shocking installation did not do the original idea or the quality components justice.

The Good News: Having completely stripped out and almost completely refitted the boat following the original design ideas, we've been able to achieve a drier, warmer more comfortable boat which is able to stay off grid longer, just by buying better quality components and using professional installers (or installing it ourselves after reading the manual!)