Alloy
Well-known member
To counter shading our panels are in parallel into two large controllers.
My poor man's Earth Roamer design.
- Thread starter CappyJax
- Start date
To counter shading our panels are in parallel into two large controllers.
A solar panel flat mounted should produce 50% of its max power output when the sun is something like 27 degrees above the horizon. If you aren't getting anything when your panels are flat, then you have something wrong.
rruff
Explorer
Me too... but different strokes and all...
Alloy
Well-known member
We don't see 27 degrees from Nov to Feb.
My buddy who has tilted roof top panels on his house runs 30% in Dec- Jan.
I see you are in Vancouver. That means you experience a lower elevation of the sun which will reduce the effectiveness of your solar panels. I am not sure what your point is. This is a well known phenomena. I am not in Vancouver Canada, so my results will be significantly different.
This forum is pretty good. https://secondlifestorage.com/index.php
The SIMP BMS is a good choice because it is cheap and reliable. However, the manual is not well written and guy who designed it is pissy when you ask him questions. There are some other BMS systems that work with the Tesla modules, but they are much more expensive. Although I haven't look at them in about 6 months, so there may be better ones now.
Tesla modules are around $1,000 per 5kWh. They also have coolant lines built into them. You probably won't need to cool them if you don't exceed 1C of discharge, but you will need to heat them if they are exposed to the cold. You can discharge a lithium ion below freezing, but you can't charge them.
The Tesla modules have a nominal voltage of 22.5V, so unless you want to have a dual voltage system, they might not be the best option.
Get used to using Wh instead of Ah. I can assume you are using a 12V system, but a lot of solar users are using 48V. So, you want a 12kWh system, which is easier to convey. You could do that with 3 Tesla modules, but you are stuck with a 24V system then. I am doing 8 cells with 4 in series and 4 in parallel. So, it will be a 48V system. For the few things I will need 12V for, I will use a 48V to 12V converter.
What will you be running off your system?
awheeler
Member
Thanks for the info! I have considered using a 48v system and have looked at the Safiery system https://www.safiery.com/DIY-4WD. I would want a way to charge from engine and I do have a spot for a second alternator.
This is a full-time rig for us, induction cooktop, gas heater, electric hot water heater, and a little bit of AC use from battery. I've actually looked into some mini split AC units that run on 48v.
Does the BMS you mentioned protect the cells from charge/discharge in too cold of temps? That's one feature I like about my current Battle Borne setup.
rruff
Explorer
I've always been good with 25W... but I'm going to have up to 400W on the next one, and 2000 W-hrs of storage. The luxury!
That is pretty much the system I am building with Victron components. Mind will just be larger.
I have looked at the 48V mini splits as well. Problem is they all seem to be off brands which make finding parts and service more difficult. Also, they are more than twice as expensive. If you are going to have an inverter, cheaper to just go with a 120V mini split.
To charge off the alternator, just get the largest 12V alternator that will work with your rig, and then get an inverter that is about half that. But still make sure you aren't exceeding the continuous amperage rating of the alternator. So, if it is 300A, then an 1800W 12V inverter is a good size, and run the AC lines to your inverter charger. Yes, it will be less efficient than a 48V dedicated alternator, but a hell of a lot cheaper. A good sized 48V alternator is over $1,500. Plus, you will need to have an additional regulator which will be close to another $1,000. But a good 1,800W 12V inverter is only like $300, and you don't need an additional charge regulator as you already have that in the charger/inverter.
This SIMP BMS does have outputs to open relays and prevent charging when below freezing. It also have over/under voltage protection, and overtemp protection.
Right!? I have some people telling me 4800W is not enough, and other saying it is way too much! LOL
I am just going with the most I can fit on the roof with slide outs. My goal is to be able to put my camper on an electric pickup chassis and charge the main battery. Overlanding for free!
I do fine with a 150 watt panel and 110 amp AGM. Only thing I need electricity for is to run some lights, fans, radio, and charge a couple things. Going all-electric just seems dumb when there are so many better ways to heat and cook. I'd rather not freeze and starve if the power goes out!
Let's keep this friendly please. That is the spirit of Expedition Portal.