Vlog 76: Winter Sun

Can a decently-sized solar array provide enough power for day to day living on a narrowboat during the winter? There’ll be sunny days, there’ll be cloudy days, there’ll be rainy days and maybe even snow – but can the panels pull in the power? In this video, I do some sums.

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  1. Mark Fay MMC Jr. Engineer QMED AS-E / MSC ET

    I made a incorrect assertion is my post yesterday (January 26) and it was a darn fool error. Yes the current will be limited in the serial connection of the array to that of what the single array is capable of. However, because of the increased voltage the total array wattage will in fact be cumulative and not limited to the capacity of one array. So sorry. :-)

    Having realized my stupid mistake I withdraw my January 26 post.

    • I’m so pleased you spotted that as it’s saved me the trouble of writing out a long-winded rebuttal!! I have removed your other comment as requested. Cheers

  2. Hi
    Do you have to run the engine to create hot water?

    • I don’t have to as I have an diesel-fired heater unit for heating and hot water as well as an electric immersion heater in the tank which I can use when plugged into a shoreline. Many boats have multiple ways of heating water like this.

  3. This may be of interest to some of you with solar power. A video of an Epever Tracer MPPT and winter results as paper graph.


  4. Did you notice that on your low input shots your MPPT controller actually had the panels down at close to battery voltage and was not tracking the maximum power point? This is an issue with those controllers in low light and they have to see a certain minimum current before they start tracking. (I spoke to the manufacturer about this) That is one reason why I advise people to connect panels in parallel rather than series as this increases the input current so they track earlier and more reliably. The MPP on yours looked to be quite high in series, around 90V I think so the lost power if they are being held at 14v is not insubstantial. The other reason for paralleling is that you get better performance with partial shading. The only advantage to a series connection with these controllers would be if there was a very long cable run which there isn’t on a narrowboat.

    • All a bit beyond me, I left it to the installer to set it up. Seems to work though.

    • Here in the US, we prefer microinverters on each solar panel (effectively parallel wiring) to string inverters, which are wired serially. The newer model microinverters are exceptionally good at harvesting solar power at the lowest levels and because each panel is wired separately, the deleterious effects of shade and shadow on one panel do not affect the power generation of the others. There are other advantages as well, so have a look at this option if you are considering a new or replacement solar array.

      • Hi. I’m a little confused by your term “inverter” because to me an inverter is a device to take the battery 12V DC and convert it up to 230V AC mains; generally such an inverter would run from the batteries, with the solar connected to the batteries via a charge controller (in other words, the solar wouldn’t go into an inverter directly). Perhaps this is a terminology issue..?

  5. David, Have you found it ok that the solar panels only tip two ways, & would it help much to tip the panels a lot more using say a garden chair wile moored as you are in December – Feb, march?

    • It would not help because even if you doubled (which won’t happen) the output you’d still only be getting a miserable few Amps and for not many hours. It’s better, sure, but not enough.

  6. Brilliant and spot on. We have 400 watts on a very power hungry boat, we’d get through 100 – 200 Ah during the afternoon and overnight. In the summer on our 3 month cruise, I only had to run the engine to charge up the batteries once, on a rainy 4 day stopover in Stone. The only reason we fitted solar was to prevent us having to run the engine. A boat with a cocooned diesel generator is probably the best solution. Like you we have had 15 amps during winter days but not for the 10 hours you’d need.

  7. Hi , do you have the highest capacity panels available? presume this changes as things develop….

    • You can get bigger ones but the ones I chose were the highest capacity in the smallest footprint that was suitable for my roof.

  8. Great info thx!
    Ive only got one panel and room for two more, I’m guessing we’re pretty power hungry do you think it would be worth adding the extra panels?
    Also my wife wants to vlog on a totally different subject, what video editing software do u use, you do a great job with it!!

    • I don’t think you can ever go wrong with having more panels as long as they aren’t in the way of you accessing the roof (eg in locks etc). I’d say spend the money for the highest-capacity panels you can get for the space available.

      I won’t vlog about how I edit because I want to keep the channel strictly narrowboat oriented but I use Sony Vegas Pro 13.

  9. Hi, Did you get message about electricity charges in the Marina? was wondering how that system worked, or if you have done a VLOG on it?

  10. Ralph. NB Miner Bill

    Hi, liking the very handy LCD information panel, do you know where it came from? The MinerBill could really use one of those!

    • It came with the solar charge controller (all bought from Midsummer Energy) and it plugs directly into the controller (ie it does not do its readings from the battery so it is specific to that controller). The controller’s an “EPsolar Tracer-BN 40A MPPT Regulator” and the meter is an “MT-50 Display Monitor”. Cheers!

  11. Hi there, Andy and Lynda from Christchurch new Zealand here. We really enjoyed the Vlog but can we be a a pain and ask a question. You demonstrated that typically solar is not enough to charge the batteries on their own but how long do you need to run the engine to charge the batteries for a typical day when you are moored up on the cut?

    • Well, at the risk of being a pain back – I don’t know because I’ve never had to do it. When I cruise, spring to autumn, the solar is sufficient to keep me going, along with any contribution from any cruising I do. In winter I moor up where there’s a shoreline and just run off that.

      But I have a 70 Amp alternator so a couple of hours would be enough to give a decent bit of power back into the batteries.

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