David Baillie

Eugene Kenny wrote:

David Baillie wrote:Eugene, A good rule of thumb for max working voltage on controllers is panel string VOCx1.25.  When you have a cold day and the panels have not yet started producing the initial voltage easily goes over the VOC. Most MPPT Controllers can shed extra amps but not extra voltage.

Yes, I am aware of the voltage variations of PVs, based on changing ambient temperatures.  My 5 YO panels have noticeably aged, losing at least 0.03-0.06% output (the typical voltage increase when cold, for fresh panels).

David Baillie wrote:I have replaced 4 controllers for people for that very reason, all in winter.  Its less of an issue with the new high voltage controllers but the 150 and 135 volt units are susceptible to it. Blue smoke of death is not good...
Cheers,  David

Odd, I've not heard of anyone around here (or via the web) that has negligently toasted a Victron controller. The Victron Owner's manual is crystal-clear regarding maximum voltage inputs - that said, I suspect most owners do read the manual.

Trust me reading a manual is not typical! I am convinced half of my skill set in solar design is due to actually reading the manuals and following what they suggest. Having said that there is a lot of missing info that can only come from talking to their tech support people....
Cheers,  David

John Weiland wrote:

David Baillie wrote:[......  When you have a cold day and the panels have not yet started producing the initial voltage easily goes over the VOC. Most MPPT Controllers can shed extra amps but not extra voltage. ....

David, more excellent information.  Can you elaborate on this effect?  Why, between a cold or warm weather situation with the panels receiving the same solar input, would the cold panels crank up voltage without producing amps (if I'm interpreting this phenomenon correctly)?  Again, forgive me my rudimentary understanding of the forces involved, but without amps, what contributes to controller burn-up without the involvement of amperage?  Thanks!....

My understanding of the phenomenon is the cold weather reduces internal resistance allowing for a higher initial voltage while not under load. The 1.25 safety factor rule comes from outback and midnite tech support. WHo knows maybe victron is immune but it is a common design number in my area. I do deal with temperature swings down to -40 Celcius though.

Eugene Kenny wrote:I see I'm late to the party.  At any rate, glad to see your system functioning.

Just a few tidbits to add, if I may;

I've been completely off-grid for 4 years now.  My solar storage bank is basically 48 Volts nominal (4x110Ah 12V deep cycle FLA's (flooded lead acid) batteries, all connected in series. I have six 12V (nominal), 100W rated panels, also connected in series for an average open Voc of 133.8V (each PV produces, on average, 22.3Voc each.  I use a Victron Blue 150-35 controller. (the same controller you initially purchased).

I see your panel is rated at 64.9Voc (open circuit voltage). So, connecting two of these identical panels in series should yield approx. 129.9Voc, which is well under your controller's 150v maximun input voltage. Obviously, connecting three (or more) like PVs would exceed the controller's 150V maximum input voltage - and may even damage it.

The Victron 150-35 would've been OK with your 36v (nominal) system, but much better with two, series connected PVs. BTW, the Victron controller has 4 charging stages - Bulk, Absorb, Float and Equalize. It is also compatible with Lithium Ion.

Lastly, testing a PV's maximum current output (Isc=Short Circuit), is self explanatory; Shade the PV from direct sunlight first, then Just connect a short 12" 10 gauge jumper wire across both PV's output terminals. Once connected, uncover the PV and aim it directly at the sun.  Use a DC capable clamp meter  ( https://www.amazon.com/AstroAI-Multimeter-Auto-ranging-Resistance-Capacitance/dp/B08MTCMWLB/ref=sr_1_3?keywords=dc%2Bclamp%2Bmeter&qid=1694491992&sr=8-3&th=1  ) around the jumper wire. A must-have tool when tinkering with electrons!

Eugene, A good rule of thumb for max working voltage on controllers is panel string VOCx1.25.  When you have a cold day and the panels have not yet started producing the initial voltage easily goes over the VOC. Most MPPT Controllers can shed extra amps but not extra voltage.  I have replaced 4 controllers for people for that very reason, all in winter.  Its less of an issue with the new high voltage controllers but the 150 and 135 volt units are susceptible to it. Blue smoke of death is not good...
Cheers,  David

What a fascinating topic I'm just seeing this. The embodied energy discussion is a good one. If you have solar already but are choosing to not use it to it's full potential to me that means it's embodied energy is not being used to it's full extent. If you are choosing to do a trip to town instead of using the energy available on the solar array then you are adding to the energy load instead of maximizing what you already have. Consumption wise our 8 cubic foot energy star rated AC freezer consumes 700 watts per day in the summer and 550 watts in the winter based on recent kill a watt readings I took. So 256 kWHr per year. I don't particularly like the 12 volt freezers as my experience has been they are shorter lived then their now as efficient AC cousins at four times the cost. If you don't have an inverter that is a factor. Others on site have different experiences. I believe the value and energy savings long term is worth the embodied energy expenditure. Either way awesome work with all the preserving!

Paul Ladendorf wrote:

David Baillie wrote:The problem with filtration only is that most filters do not filter out gases only particulate. there are some that have a carbon layer but even that is not enough. In a tight house all the surfaces including the humans will be off gassing. The human body emits quite a range of chemicals that should be flushed from the home let alone all the cooking gases, paints, finishes detergents etc...

How do you know that "a carbon layer" is not enough?

because most gases are not absorbed by a carbon layer. It would filter out volatiles but not things like carbon dioxide or methane to name two common gases. as mentioned above plants would for sure help.

The problem with filtration only is that most filters do not filter out gases only particulate. there are some that have a carbon layer but even that is not enough. In a tight house all the surfaces including the humans will be off gassing. The human body emits quite a range of chemicals that should be flushed from the home let alone all the cooking gases, paints, finishes detergents etc...

Paul Ladendorf wrote:My little house in Northeast Alabama is going to be very tight so I'm looking at options to make sure my air quality stays good. Since I live in an area with excellent air quality, I only have to worry about air quality 6 months out of the year since I leave my windows open the rest of the time.  I'm considering an energy recovery ventilation system or an air purifier. What do you use and why?

in my part of the World (Ontario) an :HRV is a must due to a very demanding building code so very tight houses. The difference between an erv and an HRV is An HRV can better remove moisture which tends to build up in the air in a tight house.ine is set to run 12 minutes an hour to circulate and exchange a portion of the air  works great.

I retail to people at about 80-90 cents a watt in Canadian dollars. Please remember our dollar is worth 0.75 cents us when people give you pricing. I deal with these people here:
www.chargesolar.com
They have a warehouse in the maritimes. On their website the have a find an installer tool. Contact a local installer and get some pricing from them. Buy new for the small difference in price where you are.
Cheers, David

cloud The Teacher wrote:Greetings,

I'm a newbie to Solar, and although I read and read, there are still some things that are a little over my head.

The main problem is, even though I live in a country where solar is common — in this culture, it is also very common to have INCREDIBLY poor customer service.  People do not answer phones, return calls, answer emails, or even consider that they should be polite and helpful to the people who are trying to give them their money!  They will often just say "no, that's not possible" and hang up, instead of trying to find a solution that will result in them being paid for their services.  (It is infuriating!)

So I have zero confidence or faith that I will get the help that I need in this country.

And although I have learned a lot from all the reading & video watching I have done.  I still can not find the answers to the specific questions that I have.  And it seems that the most common response to ANY question is:  "Well, it depends".  But they never actually say WHAT it depends on, and what the possible solutions could be for each scenario!!!  (Or the "answer" requires a PhD to comprehend.)

So...

I am looking for someone that I can hire to do direct consulting for me.  Someone that I can have video calls with so that I can explain what I want to do;  find-out the possibilities;  discuss WHAT everything depends on;  and actually get to the point of finding-out what the actual SOLUTIONS to the situation could be, so that I can finally make a decision on what equipment to buy, and move to the next phase of learning how to put it all together.

It seems like this should not be an impossibility — but so far, I have not found what I am looking for (in almost a year of searching).

I hope that Permies and the people here can steer me in the right direction.  I hope that someone reading this is actually the person that I am looking for.  I look forward to any input, suggestions, recommendations, etc..


Have An Excellent Day,

~C.

I would start with stating what country you are in first; knowledge from one place does not always translate to another. Next I would want to know what you want to accomplish with your system. Basic lights and communication, whole home or something else.