Very annoying administrator - I was in the middle of editing my last post to add more info and hit the 120min edit limit - I was looking something up - seems like it would be better to allow a longer window or allow unlimited time if the post being edited is the last one in the thread -
Wanting a battery backup for the cpap lead me into a deep dive into solar power and batteries and all those things - I answer questions over there a lot under the same username as here.
https://diysolarforum.com/threads/robbob...ead.84402/
ANYWAYS - Here is the design with solar and MPPT
The MPPT - choose the 100/20 - i.e. 20amps and 100v from the dropdown for for $89 - Victron is top notch stuff and won't fail you when you need it most. This model is fanless - so NOTHING to fail as there are no moving parts.
I direct you to this website verse amazon because they are an authorized reseller and they provide factory support if something is wrong. AND you can get a human on the phone in minutes to help if you need something. From amazon sellers you are lucky to get a response. The shipping costs - so plan wisely and order what you want all at once. There are a LOT of cheaper MPPT, but none more bullet proof and reliable at this price point. NOTE the wire to the MPPT from the panels MUST be fine stranded
https://www.currentconnected.com/product...-250v-ved/
For the solar panels - 100w will recharge you in 4 hours of sun, or 2 hours of sun with 200w. Any size/type solar panel will do the job, but if you go much bigger there are other design considerations. These will run you $85 each. Amazon is great to get them from because they will reship if it arrives broken. Otherwise - you can get them in person at any RV supply store.
https://www.amazon.com/Newpowa-Monocryst...B09D7SMKMQ
Other changes -
breaker to disconnect the solar panels - not strictly required but nice to have - make sure to get a DC rated one
https://www.amazon.com/Pjerjzn-Disconnec...B0CQZKRDQR
2 post battery fuse - it is bad to stack lugs and this avoids it nicely.
https://www.amazon.com/BOJACK-Terminal-3...0CFWS9GZD/
You will need cables from the panels to the disconnect - 12awg will work fine for what we are doing
You can choose the lengths that match most closely and just whack the ends off of one set or buy without ends
One from the panels to the disconnect - one from disconnect to MPPT.
If you go more than 50ft use the 10awg wire. Up to 100 use the two panels in series verse parallel.
https://www.amazon.com/BougeRV-Extension...B08DC9LS1Q
If you live in Florida and want to keep your fridge running after a hurricane - This little guy will do the job along with the cpap setup. NOW you might want a bigger MPPT and a 200ah battery and more panels to do the job and keep things topped up. That is a whole different conversation - you can DM me on the solar forum or DM here and we can post a thread in another sub-forum that covers that without derailing someone else.
https://www.currentconnected.com/product...v-phoenix/
AND I know what you are thinking - "Can't I just buy one of those solar generator thingies? The answer is yes, sure you can - but they cost more than twice as much for the same battery size and if something goes wrong they are junk instead of being able to replace whatever failed yourself. Not to mention the propriatary solar panel connectors are just stupid.
And - disclaimer - mounting panels to a structure or in a permenant fashion requires all sorts of care. If you are camping or power is out because of a storm - throwing a pair out where they can't blow away but will charge your battery is a wonderful thing.
Thank you! I would not have known that!
