Best Practices: multi-day surf camping

[satbty1]

Hello to the members of the forum from a new member. I've appreciated the activity here and hope to learn some best practices for keeping safe while having fun with a small system.


Here's what I am working with today:
1. Wind Turbine, https://bit.ly/2DOSBvj
2. Charge Controller, http://ebay.to/2pDp43J
3. Battery Panel, http://ebay.to/2GforXA (one panel now, planning to purchase more to place on the ground on location)
4. Telecom AGM 92AH, https://bit.ly/2Gkrf5P (planning for how best to replace this)
5. Wild AC Rectifier, http://ebay.to/2uagGxb
6. Shunt+Meter, http://ebay.to/2ILd1Jf
7. Air Heater (x4), http://ebay.to/2ILi2Sr (hopefully to be used as a load for the turbine for space heating)
8. 10AWG wire

So the goal here is to provide stable power during multi-day surf trips, in locations where the wind can be assumed to be blowing quite a lot. If "quite a lot" doesn't cut it for providing advice, lets say 20kts for 8 hours a day.

The set-up is carried around in a Volvo wagon, where I currently have the PV panel fixed to the roof-box, and some framing set up for the turbine. The controller is housed in the roof-box, along with my single 92AH telecom AGM battery. I just recently learned- from reading on these forums- that I have a battery which is probably going to fail me quite soon. I've been using it to run an electric blanket each night for a month only, and paid $70 for it. Battery advice would be most welcome. If I can spare $1K should I consider LiFeP04?

I am primarily interested in anything that veterans of these technologies are able to point out to me as points for re/consideration. I am new to the practical application of DC systems, but as a junior in a mining engineering degree, I have some basic electrical engineering under my belt.

I would to like to field one question in particular: can anyone educate me about the charge controller I purchased? I tried to read the fine print and ensure that I would get an actual MPPT unit, and I'm interested if anyone can shine some light on this model.

Many thanks.
-Ty

[Mike90250]

The charge controller looks like a sales pitch. Wonderful stuff, and will re-grow hair on a bald head

But everybody on ebay makes wild claims. Let us know if it works.

[satbty1]

Well, it's been quite a journey of new discovery working from my original plan to my thinking today. The eBay charge controller does not appropriately match (buck) the PV VDC output to ideal charging voltage per the nominal VDC on the battery bank. In other words it does not do MPPT.

I'm concerned with the potential damage this controller may do to my battery bank and so have chosen a new path. This is to embark on building MPPT controllers for myself... according to DIY information on the web. Anyway, I would like to field a question to the forum:

Working with:
500ah 12V battery bank (AGM)
4x 100W PV panels-- Voc 24.6-- Vmpp 20.5-- Isc 5.36-- Impp 4.88


I am interested in the possibility of building an MPPT controller for each panel... given that I will be building the MPPT charge controllers from scratch. The benefit that occurs to me is that this allows each individual charge controller to be handling a lower current-- i.e. instead of a single charge controller handling all 4 panels-- and therefore component selection is made easier. This simple sketch shows my idea in general terms (please note the listed power outputs were only to allow very rough calculations of amperages in given wires).

Any caution or advice is most appreciated.

[bcroe]

I would expect that the current would not be at all balanced, perhaps does not matter. But
putting panels in series would cut current and reduce the number of parts. Bruce Roe

[Mike90250]

......

I am interested in the possibility of building an MPPT controller for each panel... given that I will be building the MPPT charge controllers from scratch. The benefit that occurs to me is that this allows each individual charge controller to be handling a lower current-- i.e. instead of a single charge controller handling all 4 panels-- and therefore component selection is made easier. This simple sketch shows my idea in general terms (please note the listed power outputs were only to allow very rough calculations of amperages in given wires).

Any caution or advice is most appreciated.

You will need to have some good electronic engineering to accomplish this. There are no "building blocks" that I know of to piece this together.

[satbty1]

I would expect that the current would not be at all balanced, perhaps does not matter. But
putting panels in series would cut current and reduce the number of parts. Bruce Roe

Right. If I understand, your point is that each panel would be putting out different power (i.e. varying voltages, unlike in my diagram), and therefore each MPPT controller would be outputting different currents, although identical voltages as determined by the ideal charging voltage. It would seem to me this wouldn't be an issue as the currents would simply sum into a large current delivered to the battery, at the ideal charging voltage?

[satbty1]

You will need to have some good electronic engineering to accomplish this. There are no "building blocks" that I know of to piece this together.

This website is hosting the arduino code which implements MPPT by applying the "hill-climbing algorithm" to essentially reach the knee of the IV curve that your PV panel is actually working in. It accomplishes finding the MPP by iterative comparisons of power measurements.

https://microcontrolere.wordpress.co...solar-charger/

This is what I am interested in building.

[bcroe]

With multiple MPPTs you may find hunting back and forth between them
when reaching charge limit. Building a solid buck converter of substantial
power is not as trivial a project as it may first appear. It ought to be a great
learning experience. Some MPPTs use an algorithm more complex than the
simple hill climb. I hope you have a good storage scope and know how to
use it. Bruce Roe

[satbty1]

Building a solid buck converter of substantial
power is not as trivial a project as it may first appear.

I appreciate this comment. In fact, I have to admit that I hadn't looked at the actual prices for pro MPPT controllers under 30A on the market... I think that with a price of around $200 USD it may pay dividends (especially in time commitment) to buy one. Also, this is my first foray into building/installing a PV system, and I can't say I understand completely how to think about what bcroe mentioned about issues at charge limit.

Looking at the Blue Sky 2512 iX -HV (https://www.solar-electric.com/lib/w...2HV-manual.pdf) it seems very solid. Would anyone have recommendations for MPPT controllers for 12V systems under 30A?

Thanks also.

[jflorey2]

Looking at the Blue Sky 2512 iX -HV (https://www.solar-electric.com/lib/w...2HV-manual.pdf) it seems very solid. Would anyone have recommendations for MPPT controllers for 12V systems under 30A?

I do not recommend Blue Sky based on my experiences with their products. I'd go with Victron instead.

[Mike90250]

...I appreciate this comment. In fact, I have to admit that I hadn't looked at the actual prices for pro MPPT controllers under 30A on the market........

I would recomend the Morningstar series of MPPT I've had really good results with their algorithm, it beats the 4 algorithms in my Midnight Classic every time, every condition. You can use it to compare your MPPT implementions. They have a bit of a trick with their model numbers/names, be sure you are getting the MPPT version, not the $200 less expensive PWM in the same shape case. Their MPPT 60 has a nice web server, if you want lots of data.

[sdold]

I admire your can-do spirit, but although I am very comfortable doing something like this (I build a lot of Arduino-based custom boards), there is no way I would bother with this when there are so many good, cheap MPPT controllers on the market. Just buy a good controller and cross off one more thing that could ruin your trip.

[littleharbor]

Blue sky controllers have terribly low input voltage limits for an MPPT controller. The model you've indicated is their "High Voltage" model. Boasting a Max Voc. of 50 volts, with a recommended max of 40 volts. That's nuts, especially for their HV model. PLUS note that their cheaper 2512 model has a max Voc. of a whopping 57 volts. 7 volts higher. It makes no sense.