Interested. Can you point me in the direction of the type of battery/BMS you’re referring to? Maybe a tutorial? Something like CALB cells, I assume?
Viability of Solar for emergency backup?
- Thread starter Rusty123
- Start date
Maast
Compulsive Tinkerer
The thing is, running a generator at near idle for small loads is horribly inefficient, and with a diesel genset will actually cause failure in the long run (they coke up). With a large enough battery bank you can run the genset at 3/4 load, charge the batt bank in 4-6 hours and quietly coast on stored power for a day or 3.
Fuel storage however is a problem, don't bother storing gasoline, its almost impossible to keep it viable for more than 3 years no matter what you do. Diesel does store well though, but it can't touch metal, and has to be pretreated and kept in a airtight container that's had its oxygen purged prior to sealing. Dropping a block of dry ice in the diesel and waiting until the hissing from the cap stops and then screwing it down tight does this well. Propane easily stores forever but it has a very low energy density and you need a HUGE expensive tank to store enough for 6 months of use.
Solar around here just isnt viable in the winter unless you have a very large array, and then you horribly overproduce in the summer. Selling it back to the grid does a bit to offset the cost, but it's pennies on the dollar spent.
Fuel storage however is a problem, don't bother storing gasoline, its almost impossible to keep it viable for more than 3 years no matter what you do. Diesel does store well though, but it can't touch metal, and has to be pretreated and kept in a airtight container that's had its oxygen purged prior to sealing. Dropping a block of dry ice in the diesel and waiting until the hissing from the cap stops and then screwing it down tight does this well. Propane easily stores forever but it has a very low energy density and you need a HUGE expensive tank to store enough for 6 months of use.
Solar around here just isnt viable in the winter unless you have a very large array, and then you horribly overproduce in the summer. Selling it back to the grid does a bit to offset the cost, but it's pennies on the dollar spent.
400Ah at 12.8V is around 5KWh storage. There are many cells in the price range, and many threads and videos on building and setting up the BMS.
Charging via solar is going to be tough in your area, but using a generator works, natural gas, diesel, propane, etc...
To effectively recharge in your area, is going to take a 5KW array minimum... and that is a LOT of amps... if you can get 2 to 4 hours of effective sun, it can be recharged with 1 to 3 KW, BUT realistically, 5KW is needed... at 12V...
Building for 24V or 48V lowers the amps needed, but increases the complexity of the build.
If you seriously manage the electricity usage, only run loads during sunny hours, trickle the loads a 400Ah pack can be minimally drained, and recharged via sun... but we are talking extreme minimum usage... except on sunny days... the generator recharging the bank would be better than solar in the portability SHTF scenario
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