Guide: Installing a solar panel on the HCH-II (step-by-step)

Discussion in 'Articles' started by msantos, May 7, 2008.

  1. msantos

    msantos Eco Accelerometrist

    Upgrading the solar panel on the HCH-II and the 2010 3G Prius

    OK, here we go again. This time my solar power generation was bumped up to 15 watts of ultralight, mono-crystalline goodness.

    I had bought quite a bit more power and at first I intended to fit it all in (up to 30Watts) but I decided against it since it would be a bit of a waste - at least for the time being. I realized that 15 watts is now more than sufficient for the power demands I have in the HCH-II.

    One good outcome of this upgrade is that the solar assembly I got now is ~4 times lighter than the previous one. The new panels are just a few milimeters thick and with an aluminum backing now they are not only light but also very flexible.

    So let's see, I went up tripled the generated power and I cut the weight to just one quarter of the former setup. I am happy.

    Did I get a charge controller installed? Nope. Not yet, and like I said previously I have no need for one since the 12V battery will take all it without overcharging. Since these are the raw panels, I still had to retrofit the panel with a diode just to prevent the battery current from flowing in the opposite direction at night. No problem though since diodes are some of the most common items on my bench.

    So here are the pics of the new panel setup.

    Like the previous setup, the new panel is attached to the rear deck platform with industrial velcro. Noiseless, secure under all weather conditions and leaves no traces if ever removed.

    And now a special treat for the other new hybrid in my fleet:
    A nice 5 watt solar panel velcroed in on the front dash of the 2010 Prius...

    ... with yet another 15W unit attached to the rear cargo cover at the rear of the vehicle.

    OK, I know what some of you are thinking: That's such an odd place to place a solar panel. What if you need to carry something large and the cover has to come off?

    Well, that's pretty easy actually. The solar panel has a connector that unplugs from a concealed wire that climbs up the middle of the rear seat... and it too is attached with industrial velcro to the aluminum cover cartridge. In other words, easy to remove and easy to re-install.

    In reality though, I rarely use the Prius to carry anything I cannot carry in the HCH-II. I know this does not help capitalize on the Prius' much touted advantage over a car that cannot even fold its seats, but in my case it is the absolute truth. For folks like myself the cargo versatility of the Prius is seriously overrated and not worth making a car choice on this attribute alone. Sorry. :rolleyes:

    Anyway, why did I install two panels on the Prius totaling 20 watts?

    Because the 2010 Prius will take it all and much more. In fact, I have a 30 Watt flexible panel that will be installed over the rear cover and it will not only help power the solar cooling setup on the Prius (similar to what I did on the HCH-II) but it will also help supplement the 12V battery charge as well.
    In this setup I will use a charge controller however.

    The "how to..." for the Prius will arrive sometime in the future.


  2. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    This is exciting, Manuel! I eagerly await your how to for the Prius. :D
  3. cephraim

    cephraim Noob

    Can you provide a link to purchase the raw panels?

    Also, why do you feel that the controller is not needed?
    I had one in my setup, but always wondered whether that was limiting the benefits, as it seemed to stop charging too early....
  4. Jess

    Jess Well-Known Member

    Hi MSantos,

    How has the fan set up been working out for you? Do you still feel it was worth the install? I've been considering it, but keep putting off. My windows are tinted 35%, so is there a particular type of panel you recommend when using w/ tint?
    I would like to keep it to 1 panel, if I can. Is it worth it to have 4 fans to one panel or is 2 truly better in a 4 fan set up?
    Are you still happy w/ the type of fans you're using or have you found anything better since?

    Sorry for all the questions, too.

  5. cephraim

    cephraim Noob

    Do you have any pics of the fan set up?
    You ever try anything for the winter in terms of heating?
  6. msantos

    msantos Eco Accelerometrist

    Hi cephraim;

    Most vehicles do not drain much more than 50mA from the 12V battery while powered off. For that reason you have to be sure that you do not overcharge the 12V battery whenever your generated power goes above 5 watts. That is why we always recommend a charge controller just to saty on the safe side. Now, depending on the charge controller you may or may not have additional losses that nullify the value of the panel's contribution.
    For instance, if the charge controller consumes let's say, 30mA... then that is 30 mA of current that will not make it into the battery. The more it consumes the less effective the solar panel setup is. Try measuring the power demands of the car and that of the charge controller, then decide if you are better off without a charge controller at all. Also keep an eye on the 12V battery to make sure it does not overcharge.

    In my case, my car is consuming much more tham 100mA at all times. This is because I've added a host of additional systems that are ON all the time. The most recent and also the most power hungry is a 2 camera video surveillance system. Given the significant power drains I am going to forgo a charge controller altogether on my HCH-II.


    The Solar powered cooling mod (cephraim, pics are provided here too) worked so well that I am definitely going to put in on my 2010 Prius as well. In fact, I even ignored the Prius OEM solar solution not because the hardware is not good (it is in fact excellet with 60Watts of generated power), but because the implementation and usability is so limited darn limited.

    No, I did not contemplate the "heating" part. Quite frankly, I am not too sure how to go about doing it with the current state of technology.

    The vendor I obtained my solar panels from also has an eBay outlet. You can find it here.


  7. danb01

    danb01 New Member

    Is the trunk light circuit always on ( before the trunk light switch )?

    If so... Why bother running a wire all the way to the front of the vehicle?

    The wire bringing 12v to the trunk light switch can be back feed with the solar power!!

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