Safe Harbour | Solar in the PNW?

For the last several years, Kevin and Laura have had solar panels installed on Airship. As we cruised together, we compared notes about electrical systems. Despite their enthusiasm for solar, I remained a solar skeptic (maybe even a solar curmudgeon!). I figured I already had a fancy alternator and reasonably sized battery bank. I only used the generator occasionally, typically when I needed hot water and hadn’t run the engine that day. What problem would solar be solving?

Who needs solar when you have a generator and lots of batteries?

Let’s back up a moment, and look at why I didn’t think solar made sense…

First, I’m not a power conserver. My inverter runs 24/7. I routinely burn through 300+ amp hours (at 12V) a day. Cruising, to me, is not about seeing what I can do without. It’s not camping. I’m not interested in sponge baths, doing dishes in cold saltwater, being uncomfortable, or worrying about turning the microwave on to reheat something for lunch.

I’m also underway a lot during typical summer cruising­–at least four hours a day, and I tend to move every day. When I’m alone on the boat, four hours underway is all I need to charge the batteries to near 100%, fill the water tank from the 12V watermaker, and have enough hot water stored in the water heater for a shower on arrival and dishes in the evening.

If other people are on the boat with me, the situation changes a bit. I’ll often run the generator in the morning for an hour or so, so we have hot water to shower and clean up after breakfast. If I don’t go anywhere for a day, I’ll run the generator to charge the batteries and make hot water.

Some people hate generators. I don’t. Mine just isn’t that annoying: it’s audible, sure, but not objectionable. Outside the boat, it’s whisper quiet—way quieter than a lot of furnaces. When rafted to other boats, I’ve occasionally apologized for starting the generator, only to hear from the rafted boat that they didn’t even notice.

My principal objections to solar were thus twofold. First, I didn’t think solar would make enough power to have a meaningful impact on generator use. And second, I didn’t see the need, since I already had as much power as I wanted through existing equipment.

Last summer’s trip down the west side of Vancouver Island was different. Because the distances were often short—sometimes less than an hour—the alternator didn’t have time to recharge the batteries. No problem, just run the generator. Until it stops and won’t restart, at which point there are a few options: head to a dock with shore power (often inconvenient or unavailable) or run the main engine and charge the batteries with the alternator (not good to run the main with such a light load). So I started thinking about alternatives.

Some cruisers carry a small portable generator for this occasion, but this seemed like a poor solution. The portable generator would be expensive, take up lots of storage room, require annual maintenance, and be seldom used.

Solar seemed like an interesting possibility. It wouldn’t totally solve the redundancy problem, since it’s not exactly power-on-demand, but there were lots of benefits. It would just work, no maintenance required. It would be good for the batteries, keeping them more fully charged and providing a nice “float” charge that can’t be efficiently applied by a generator and battery charger. Most importantly, it would be useful even when the generator was operating normally, by providing some extra power whenever there’s daylight.

I quickly realized that when I ran the generator most—like when cruising short distances last summer on the west side of Vancouver Island—the solar would be most valuable, since I needed the power AND the days were long and sunny.

I started to measure and do math. The pilothouse roof was basically wasted space, so I wasn’t giving anything up by putting panels up there. I discovered two 365 watt panels would fit easily. Research suggested this should be good for about 200 amp hours during a typical summer day in the Pacific Northwest. Enough to make a difference, to keep the batteries nearly charged. Instead of running the generator for three hours a day to charge batteries, I could run the generator for 30 minutes—enough to heat water and provide a little charging—then the solar would do the rest.

So I bit the bullet, ordered the panels and controller, and arranged to have them installed.

Two 365 watt LG NeON R panels mounted on the pilothouse roof
Despite the shading in the above picture, the panels are still putting out 349 watts

They’ve been installed for a month now and they’re exceeding expectations. February in Seattle isn’t exactly prime solar power season, but even on their worst day the panels have made about 30 amp hours—not much, but something. On sunny days, the results are much better. Several times I’ve seen daily outputs in the 140-150 amp hour range, enough to cover the electricity consumed during daylight hours and add a significant amount to the battery bank. During summer, when the days are many hours longer, the results will be even better.

The Victron solar charge controller has bluetooth, and can be accessed using a smartphone. This screen shows historical daily output.

Once solar panels have been bought and installed, there’s nothing to do other than clean them periodically. They harvest previously wasted energy silently, passively, and for free. So now, when I’m sitting at anchor with the music on and computers humming and refrigerator keeping the beer cold, I look at the ammeter and see a +, and I feel like I’m getting something for nothing.

No generator, no engine, no shore power. Just solar powering all the loads on the boat and charging the batteries.

11 thoughts on “Safe Harbour | Solar in the PNW?”

  1. On the hot water topic: Will a hydronic diesel heater also provide hot water for the house needs? Or is that not easily configurable? As a sailboat guy, solar is desirable but hard to install without shade from masts, booms etc diminishing output. I run my engine for battery charging and hot water, but I always wonder about heating water some other way. Propane tankless water heater? Diesel furnace?

    • Hi Kevin, yes a hyrdonic diesel heater could also provide domestic hot water. My boat already has a functional forced air diesel heater and swapping out to hydronic would be a major project. Since I get hot water when the main engine has been running (coolant loop), when the generator is running (electric element), or when plugged into shore power (electric element), spending the money and time to switch to hydronic hasn’t been a priority.

      Of course, there are other plusses and minuses to hydronic. The plusses are hot water, more even heat since there’s a lot of thermal mass, and zoned heat. The minuses are greater complexity (so many places to leak coolant!) and slower initial heat delivery.


      • Thank you for your response. I agree, swapping heatings systems is a major expense and effort, and hard to justify if your existing furnace is fully satisfactory!

        • One other alternative: heating water electrically using the battery bank and inverter. Kevin and Laura do this on Airship. The problem is you still need to make the power eventually. It can be good in the morning if you want hot water, have extra battery capacity, and will be running the main engine or generator in a few hours anyway.

          Propane tankless seems like it would make a lot of sense, but I’ve never seen one that’s ABYC approved for use in a boat.

  2. We have purchased the same panels and are wondering what mounting hardware/brackets you used. Also what model of controller you used..THX
    M/V One Life

  3. Thanks for posting Sam.

    I made a comment & somehow it got lost. I will try again.

    We have a similar setup having installed 2 x 275 W panels with an MPPT controller 2 years ago on our Nordic tug 37.

    Even this time of year, we gain a good boost from the panels and during the months of April through September a great boost with sustained charging currents of over 25+ Amps.

    One issue that you haven’t mentioned though is the nature of AGM batteries is that they do not take kindly to partial recharging. To keep them healthy and avoid sulfating they like to be recharged to close to 100% SOC on a regular basis. Much of the year, with the ongoing draw and fluctuating light levels, Solar will not get them to a 100% SOC.

    Lithium batteries are much happier without being taken back to 100% SOC but they require a significant cash outlay and will not play nice with other AGM’s onboard (Start battery, Thruster batteries etc.) requiring a different charging profile.

    Another option is to consider a newer type of battery – Carbon Foam AGM’s (Firefly). Like Lithium ion batteries, they are supposed to be happy floating between 20-80% SOC without sulfation and will accept the same charging profile as any other AGM’s on the boat. One can minimize or even avoid generator runs when the only reason to run the generator would be to “top up” the AGM’s to 100%.

    We recently installed 6 of these for our House Bank. So far they seem to be working well but only time will tell how they tolerate this more loose charging strategy.


    • Hi Evan! Your install looks great!

      I’m old school when it comes to batteries…nothing fancy, just 6V Dyno flooded golf cart batteries. The current set is three years old and performing very well. I add water a couple times a year and don’t worry about them the rest of the time. At ~$750 for six, I can replace them about four times for the same price as one set of Firefly’s and at least eight times for the price of Lithium. Because the flooded lead acid batteries are relatively inexpensive, I don’t worry if I shorten their life somewhat by a few deeper-then-usual discharges or occasional sub-optimal charging.

      The newer technologies have other advantages like more usable capacity, faster recharge time, higher energy density, no maintenance, no potential for off gassing, but these attributes aren’t particularly important to me.

      If I thought I’d still own this boat in 10 or 15 years, I’d probably put lithium in. But for now, I can’t justify the premium for AGM, let alone Firefly or lithium.

      • Thanks Sam.

        Flooded Lead Acid is a great option, maybe even the smartest option since you can always run an equalizing cycle on them and speed of recharge and weight are not really an issue. I should have probably entertained that option more seriously but with a bunch of other AGM’s on board… I may have been sucked into the all or nothing mindset.

        In any case, it is a very nice feeling sitting at anchor off the grid in silence and looking at a full battery bank courtesy of the sun.


  4. Great update…can you share more about where you purchased the panels, brand, the cost of the panels and installation?
    A couple of these panels will ease the amp drain with our devil – the icemaker!!

    • I bought the panels at Platt Electric. They appeared to be cheaper at a few online outfits, but by the time shipping was calculated they weren’t. Panels were about $1200, controller was about $300, install and miscellaneous was maybe $800.

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