I'm looking for a small solar kit or bits needed to keep a chest freezer running 24/7 completely off grid. What should I be looking for?
Solar Kit to Run a Chest Freezer 24/7?
figarow on 21/10/2016 - 14:11
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ground state
These videos may give you a fair idea:
https://www.youtube.com/watch?v=rk7R3NDsFiU
https://www.youtube.com/watch?v=SPoeoORhq_YYou may also want to check out his blog and eBook.
Watch this video to understand some of the most basic concepts.
You'll need a system that will meet the wattage requirement of your freezer - so check what that will be.
How does your freezer run? 240V? 12V? For a 240V output you'll need a pure sine wave inverter so you don't destroy the freezer. Cheaper inverters produce crappy signals that can fry your appliances.
Don't forget that the inverter is not 100% efficient and hence you'll need to account for that in the wattage of your system.
But just watch some YouTube videos explaining how it all works. If you like learning, you can get all the parts yourself and put it together. If you like spending money, there are plug and play style systems out there that mean no hard work for you to do.
How big? Might be cheaper to buy a camping fridge that will naturally run on 12V
How much power does it use?
If you start with one of those $20 plug in power meters, you need to record the peak power usage (expressed in watts or amps) and the cumulative power consumed over a few weeks at least, to get an idea of the average.
Some example figures might be peak 250w, avg 1.2kWh per day usage (this is approx right for my upright home freezer, a caravan/camping freezer will use half or a third of this).
Then you need to work out what size battery accommodates that. That is about 100amp/hours of a 12v battery. Add 20% for inverter/charger losses, and you would run a fully charged 120Ha battery to zero in 24 hours.
But you can't run a battery to zero without doing it damage over the long term, so you need some capacity in reserve, but you also will generate some power everyday from solar panels.
To fill a 120A/h battery on a sunny day would require approximately 360watts of panels, and add a little for conversion, so 400watts.
So if the location you are using is sunny all year, that is the answer, 400watts of panels, a 120Ah 12v battery and a charger/inverter that can comfortably accommodate 400w input and 250w output (I would add plenty of head room here, as the peak capacity on inverters/chargers is often misleading).But most places are cloudy at least some of the time, and you get less sun in winter (but a freezer will use less power, so I won't make an allowance).
People with off-grid solar powered houses typically install 3x as much battery power as they use in a day, this gives them a buffer for a cloudy week.
I don't recommend this, as the cost of panels has dropped a lot, and even on a very overcast day, you still get some power via the clouds (probably more than 25% of capacity).
So I suggest you get around 800w of panels and around 250Ah of batteries.
Ball park costs?
800w of panels, around $800. Add a battery, around $500, although I would run two 120Ah for redundancy, so you could limp along at half power until a replacement arrive should one fail. Plus a suitable charger/inverter, maybe $500? These prices are what I grabbed off ebay, so you won't do dramatically better, and could pay double if you call aspecialist to come and do it for you instead of DIY.I would be confident to store a freezer full of food with that setup. The only other thing I would suggest is a temperature monitor. They use these to monitor refrigerated trucks etc. and they record the maximum temp since it was turned on. This is just for safety in case you were away from the freezer during a long cloudy spell and the power ran out and the freezer thawed, but then refroze later. The monitor would let you know that had happened.
Wow, nice reply :)
TL;DR
It'll cost hundreds in parts and take 10 years to break even.
Yep. If you have the grid on. If you haven't, it's cheaper than getting on.
Zero point energy