Our Electrical Refit and New Catamaran Solar Arch


Last Updated on July 10, 2023 by Amy

The biggest project on our 2022 refit was an electrical reimagining that was centered around our new solar panels. We had several goals we wanted to accomplish to set us up to cruise the next five years.

What We Had in December 2021

Since 2014, Starry Horizons had 1060 watts of semi-flexible solar panels spread out around the coachroof. We’ve never been 100% convinced that (despite the marketing) semi-flexible solar panels are as efficient at turning sunlight into energy as rigid panels. That, combined with the fact that the semi-flexible panels are eight years old, meant we were not getting much solar into our batteries.

The boat came from the factory with AGM batteries, which we replaced with Lithium batteries. We have a 1000 A battery bank and did not change that in the 2022 work.

Starry Horizons came with a Cummins Onan 11.5kW generator as the main source of power while at anchor. We also had a frequency converter for our main source of power while at the dock (which we would not have done again, see the post!).

Shore Power Converter Installed

We also have 120 A Balmar alternators with external regulators on both of our engines which we installed in 2018 and in December 2019 we installed a hydrogenerator. Neither of those have changed in 2022.

Another integral part of our energy system was the inverter/charger. We had a Victron MultiPlus rated at 3000w for inverting and 120amps for charging. This unit is very important to the overall system, so I’m going to give an extremely simple explanation that will make all the EEs hate me (sup ya’ll. MechE ftw).

When we were sitting at anchor on most days, the MultiPlus acted as an inverter, taking 12V power from the batteries and inverting it to 110V to power things like plugs. The solar panels were pumping power into the batteries. Most of our ‘big’ systems, like our CruiseRO watermaker and Dometic Cruisair air cons, would have used way more power than our solar panels could produce. So we chose not to wire them in through the inverter.

Instead, when we turned the generator on, it would provide power to the watermaker and air cons directly. The inverter/charger would switch to charging mode, and it would take power from the generator and charge the batteries.

On the power consumption side, we had:

  • a CruiseRO watermaker (110V)
  • six Cruisair air conditioning units (110V)
  • washing machine (110V plug)
  • two laptops (110V plug)
  • a media server (110V plug)
  • fridge (12V)
  • freezer (12V)
  • cockpit fridge (12V)
  • AIS (used for anchor alarm, 12V)

The Cruisair and CruiseRO had to be run concurrently with the generator. Our water heater could either get power from the generator or use the port engine cooling system to give us hot water. While underway, we had additional drain from the autopilot, our Raymarine navigation equipment, and radar.

How did all this work for us? At anchor, we ran our generator every four-ish days. While generating power, we ran the watermaker to completely fill the tank and had to run air conditioning units to add load to our massive generator. With guests came increased water consumption, so we were running the generator more frequently.

At sea, it depended on how much we were motoring. If we hadn’t motored all day, we would need to fire up an engine to top up our batteries.

What We Wanted

We wanted to get rid of our diesel generator. It was loud, one more thing to maintain, and was always far too big for what we needed.

We wanted to run an air conditioning unit downstairs during the day to make that cabin more comfortable while David worked. David runs hot.

I wanted hot showers. Even in the Bahamas, in the evenings or after a swim in the ocean, I get chilly enough to want hot water. I run cold.

The New Solar

We’d seen many boats in the Bahamas in 2021-2022 that had solar arches off the stern of the coachroof. This allows boats like us to have rigid, high efficiency solar panels.

After much research, we selected Canadian Solar panels. We could fit five of the 450W bifacial panels lengthwise off the coachroof just behind the traveller. We already had three semi-flexible solar panels in that location, so we removed them and redistributed them – one was moved forward of the traveller, one was moved up to the helm hardtop and the third was no longer working and was thrown away. This left us with 940 watts of “legacy” solar panels.

The new solar panels are rated at 2,250 watts total, plus they are bifacial solar panels, which means they also generate power from sunlight on the underside of the panels (reflected off the water, for example). Our total rated output of all our solar panels is now 3,190 watts. However, the bifacial panels can theoretically generate up to 30% extra from the underside. That would put their output at 2,925 watts and our total output at 3,865 watts. In reality, our 8 year old panels will have degraded and it’s highly unlikely we’ll get a full 30% additional capacity out of the bifacial panels. So it’s tough to know exactly how much solar power we can expect.

Next, we needed someone to build the stainless steel arch for us. One of our requirements for our 2022 haul out facility was the ability to manufacture the arch. We selected New England Boatworks in Portsmouth, Rhode Island. We worked with their team to design and install the arch.

One of the welders, Chris Johnson (@legendmetalco), was so fun to work with. He invited us in to watch and film him welding. He’s a very talented welder, and the quality of our arch is superb. It’s very sturdy, possibly even too beefed up!

The main frame was bolted to the coachroof. Two support rods were welded to the aft of the frame and then bolted onto our transom. We used weather stripping between the solar panels and the frame to prevent rattling (this was a mid-install discovery!).

Our Problems

As with almost every yard we have worked with, we had issues with time and costs. We had a chat with the manufacturing department before we left Starry Horizons for a month in June and hoped that the arch would be close to ready when we got back in early July, but that wasn’t the case. The arch was installed mid-September.

Costs were also a problem. The project went way over budget, completely blowing estimates out of the water. Unfortunately there was quite a lot of sunken costs. We’d already paid for the work done up to that point, plus the solar panels would have been a nightmare to try to move anywhere else. We didn’t have a choice but to keep going forward until the project was done. In the end, we paid over 3 times more than we were quoted.

Removing the Generator

With a sizable lithium iron battery bank and over 3,000 watts of solar panels, we took a gamble. With our calculations, we were pretty sure that we would not need to use our generator anymore. We could pull it out, eliminate weight, gain storage, carry less spares, and never had to hear the generator again!

We did this knowing that we had backups in place. We still have alternators on both engines, and could run those to add to our batteries. And we may need to! Our plans for summer of 2023 are to sail back up to Nova Scotia, where days are often foggy.

David disconnected the generator as much as he could – there were a few connections the yard had to come in and help with. Then the yard brought in a crane and a workforce and strapped the generator and wiggled it out of the locker.

Unfortunately a used generator is hard to sell. It’s sitting in a marine consignment shop in Warwick, RI, if you happen to need a generator!

As a result of removing the generator, we also needed to patch some holes in the fiberglass that were the intake and exhaust. More about the fiberglass projects in a future post!

Switching from 110V to 12V

Our watermaker and air conditioning units were 110V. It is much more efficient to have 12V units when you want to run them off of a 12V battery.

We took out our CruiseRO and replaced it with a Schenker Zen100 watermaker. We pulled out all six CruiseAir units and installed three Mabru 7kbtu units. More about these in future posts!

Inverting Power

Most of our power draws and all of our power generation now come from 12V, with the exception of our 110V plugs for household appliances and the water heater. With our 110V draw so reduced and no generator to be a charging source, we repurposed our inverter charger to just be an inverter. It pulls 12V power from the batteries and inverts it to 110V.

The Shore Power Conundrum: Simplified

As we talked about in Setting up Electrical Systems on a Boat, we installed a shore power converter. That acted similarly to our generator and provided power to all 110v systems on board. Previously, the big concern was our 60hz air conditioning units and how we could supply them with the proper power while in foreign with countries. Now, with the new 12v Mabru units, we no longer had that concern and no longer needed the shore power converter (not that we really needed it in the first place). That unit is huge, so we hired the yard to help us remove it.

While our current five-year plan is to stay in the Caribbean/East Coast, someday we might head back out to the Pacific or across to the Med, so we wanted to keep that in mind.

What we decided for our shore power is a much more simplified solution. We have two new Victron Skylla-IP65 chargers that pumps the shore power directly into the batteries. They don’t care what kind of power they’re plugged into as they convert anything to 12v. Most everything on the boat now runs off the batteries and those AC systems that don’t now get clean 110v/60hz power from the inverter.

So much simpler, right?

Victron Integration

One thing you might have noticed is that I’ve mentioned Victron a lot. Our batteries are Victron, our MPPT solar controllers are Victron, we’ve got Victron chargers, inverter, shunts, etc etc etc.

David is loving it. Going with a holistic set up means devices communicate with each other and the set up is (relatively) easy. Victron has a remote monitoring system which means that we can log into the website from anywhere and check our battery status. It also has sexy reporting features.

On a Timer

The water heater and the watermaker both draw a lot of power. The watermaker came with the ability to program a time limit. We are able to start the watermaker and tell it to automatically shut off after one, two or three hours.

We took this idea and implemented it with our water heater. David installed a relay timer so that we can switch the water heater on and it will automatically shut it off after a programmed period of time. It’s currently set for one hour so I flip the switch in the afternoon when our batteries are full, and that gives us enough hot water for me to shower before bed.

In the Galley

We’ve made a few changes in the galley to give ourselves options other than our primary propane system. While we still have our stove top kettle and pressure cooker on board, we also added an electric kettle and an instant pot. We have been using the electric kettle at least twice a day and the instant pot on average once a day.

A few cruisers are switching to induction cooktops. We did talk about this, but we weren’t confident enough in our new electrical system to make the change. However, we did buy a single-burner counter top unit and swapped our stock pot for an induction-friendly one. So far, I haven’t used it!

Putting it All Together

So far we’ve discussed the major components of the set up. However, there are tons of small items: fuses, relays, wires, contactors, etc…

David did 99% of the install himself. The only exception was when we needed help running the wires for the solar panels through the frame. Wire runs are hard, and there was a lot of cursing and one and a half person projects going on.

Here is a simplified schematic of our system. It is incomplete – there are many components missing that are too small to put in and would make the schematic unwieldy. Download and refer to this schematic at your own risk.

So How’s It All Working?

Here’s a screen shot of the battery information for December 21, 2021 – January 14th, 2022. During this time, we were in Georgetown Bahamas. We may have motored a little bit around the area but most of our power was created by the generator.

A few things to note about this data:

  • There is no reporting for power coming in from the generator or engines even though we used them. You can clearly see the days we ran our generator, not in the power generated but in the power used – our consumption shot way up because we were running the watermaker and air cons and laundry and water heater, but the battery percentage increased because this data doesn’t show the power coming in from the generator.
  • When the batteries are full, the solar panels stop pumping in power. We had a day (December 20th, 2021) that shows zero solar because we ran the generator before the solar started working and when we turned the generator off, the batteries were full, therefore the solar was zero all day.
  • 40,000Wh over 24 days equals an average of 1,666 Wh per day of incoming solar (with the above disclaimer)
  • 125,000Wh over 24 days equals an average of 5,200 Wh per day for consumption
  • This data is during winter and the winter solstice (the shortest day of the year)

Here’s a screen shot of the Victron reporting from December 18th to December 24th, 2022. I picked this week because we did not motor anywhere. This is our at-anchor performance exactly as it worked.

A few things to note about this data:

  • There is no reporting for power coming in from the generator or engines because we didn’t use them.
  • When the batteries are full, the solar panels stop pumping in power. During this week, we did not get our batteries up to 100%, so this is accurate data.
  • 45,000Wh over 7 days equals an average of 6,428 Wh per day of incoming solar
  • 46,000Wh over 7 days equals an average of 6,571 Wh per day of consumption
  • This data is during winter and the winter solstice (the shortest day of the year)

We’ve changed how we manage our consumption throughout the day. It used to be that when we ran the generator, we would pile on: run the watermaker, air cons, washing machine, and water heater. Now, I try to run a load of laundry if we have a full load. We run the watermaker for a little bit every day. The water heater is switched on as we want it. Same with the air cons (we aren’t using the air cons much yet).

Another chart, showing a wider time range:

About this data:

  • We did not run our engines for power generation the entire period.
  • Dec 5 – 9th was at sea. We ran our engines a little bit during our passage from Breille NJ to George Town Bahamas when the wind died.
  • While sailing, the sails shade the boat, and thus our solar generation is less than at anchor when we can move the boom out of the way.
  • On December 10th, we ran the watermaker and an air con all day while David washed the boat down.
  • December 12th was a big laundry and watermaker day. This was also our highest solar day so far at 11.66 kWh.
  • December 25th – January 1st we had four guests on board. We motored a few times and ran the watermaker more often.
  • When the batteries are full, the solar panels stop pumping in power.
  • This data is during winter and the winter solstice (the shortest day of the year).

Looking Forward

We’ve been very pleased with our solar set up so far. We’ve been in the Bahamas less than a month, but to not use diesel for power at all is pretty amazing.

As previously mentioned, we are sailing up to Nova Scotia this summer, where the days will be long but there will be more cloud cover and fog. We are unsure how our set up will handle it, but that’s why we have redundancies.


  1. This is a great article! Thank you for taking the time to share.

    There is mention of insurance allowing you to be as far south as Georgia / Florida border – would you mind sharing your insurance company info?

  2. Great Article!
    Many have told me to consider a 24 volt system for our Helia, but seeing the success of your 12 volt system we may stay with that and keep things simpler.
    Thanks for the great and detailed info guys!

  3. It reads like you are not missing the generator! Are you altering your consumption patterns to match the solar generation capacity like on the laundry day, or is that just coincidental? Seeing many days where you hit 100% capacity, do you wish you had a larger bank? I’m looking forward to a follow up on how the system performs in the summer.

    1. We aren’t changing our consumption much beyond what I talked about in the article. I think our bank is a good size, but we will see how it goes in the grayer months.

  4. David/Amy, Thanks for your article.
    Curious about the choice of the Skyllas rather than an inverter charger like a Multiplus or Quatro to do your charging and inverting. Why two and are they in parallel?

    1. We’ve essentially separated the inverting and charging sides of the system with this new design. When plugged into shore power, we just want to charge the batteries. The Skyllas are perfect for this as they don’t care what kind of AC power they receive (voltage or frequency) and output 70amps. We have two of them in parallel as I wanted 140amps of charging capacity to cover our dockside power usage.

      For the time being, we’re keeping our old Multiplus but it’s only being used as an inverter. And because the Skyllas handle charging when on shore power, the Multiplus can provide clean 120v/60hz to all AC equipment on the boat, no matter what country we’re in. It’s another way of being fully internationally capable.

  5. One idea would be that when your batteries are at 95 to 100%, turn on the hot water heater to dump the extra solar energy. Turn it off when it reaches the correct temp.

    1. We talked about that but wanted to keep control over when it turns off and on for now. Maybe after some time has passed and we are more confident in our solar performance.

  6. Great write up, especially the detailed graphs of solar production and consumption. With our AGM’s over 3 years old, we want to make a change late this Spring before we head back to Nova Scotia and Newfoundland. You have given me several ideas to incorporate.

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