CHEAP No Battery Inverter System For Camp, Shed, Or Emergency Use

[efficientPV]

I just saw a video purporting to be a simple and cheap emergency system for emergency use. They used a buck converter and small
inverter. My garage has a small shop above it and needed to power things once and a while. Big fan of no battery systems and this
one is simple and cheap. Almost unknown in the US are 60V inverters that for some reason are popular in Europe. Usually you have
to order these from China, but a vendor is selling these in the US. Heavily discounted because they aren't selling. For $23 shipped
got this 500W inverter with four USB outlets. Listed as 1,000W and elsewhere in listing as 2,000W, internally it has one transformer
with 500W printed on it. Unlike charge controllers that power these from the battery, this one powers from the inverter transformer.
There are also two digital meters on the front for input and output voltage. The input voltage is nice to see when operating from only
panels. The real question is..... 60V is five batteries. No matter how you slice it, that is a lot of power. So, why would someone
want a 500W inverter?

The downside is this is 220V. Now my scope, power supply, laptop phone and many other things are universal 100-240V input. An outlet
strip provides multiple places to plug in. This has three universal outlets which are crap. It feels like they will snap because it
tahes so much pressure to press the plug in and there isn't even a connection for ground. I had to cut out the protective MOV in this
strip because they weren't rated for 220V.

I still have some 120V equipment, so I did a stupid engineer trick. Notice the capacitors on top of the outlet box. 220V output is from
a full H bridge. I use only half of that for each outlet. The two 1200uF 200V capacitors are in series. The top and bottom are connected
to the inverters plus and minus of the inverters 250V supply. The center of the two capacitors is at half voltage and tied to the neutral
of each outlet. That gives you AC of half the voltage. One of the outlets on the front supplies 250V to the outlet box capacitors. Having
250VDC is also nice for some testing I might do.

An inverter connected to only panels will go into fault when a cloud passes. Then it must be reset by turning the power off, a real inconvenience.
I know, I suffered with it for a couple days with that hideous alarm. The solution was pretty simple. I took a couple of zeners in series for
about 49V in series with a small 400 ohm 12V relay. The 56 ohm resistor bumped up he voltage a little bit. A relay has a nice hysteresis
of turning on about 80% voltage and turning off at 30%. This can vary a bit even with the same part number. I have this set to turn on about
61V. The inverter can drop to about 45V before the alarm goes on. The capacitor across the coil gives a little time delay. The added
capacitors for the half bridge create a longer turn on surge. Considering everything from China is focused on cost it is odd that this has two
power switches, one connected to nothing. I use that to turn on automatic operation. Though I can't see any need to turn it on when the voltage
is too low.

A 60V battery means that this should work to at least 75V. Tis is perfect for two 30V grid tie panels. These are cheap used because they are
usually cheap in the 220W range which aren't attractive to many. Now I can plug my laptop in in the evening and it will start charging in the
morning. Nice for power in the shed to recharge tools without fussing with charge controller and battery. Could be a great pond aerator pump
system. Typically, these are in the 50 to 80W range. The added panel power would give longer run time. East west array would be even better. Many
pumps are 220V optional or just use a reansformer.

My house array is 60V and this ties into that. The normal closed relay contact could be used to supply a resistive load similar to what you
are running. This would keep the relay from cycling when applied load brings down panel voltage. There are ways to use this 30V contact at higher voltage without damage.

For $23 and some old panels this makes a nice starter system.

 

[12VoltInstalls]

Interesting idea and the cost is nearly laughable.

Big fan of no battery systems

I like the buffer a battery provides. Plus you can use sun power under the moon

 

[efficientPV]

Few see the beauty of this. Our world has become USB with phones, computers, flashlights and even battery packs. We have become attached to things that are mostly self powered and are valued more than food. I've watched a few prepper videos and my first though is these people are all going to die. It is hard to adjust ones life. A 60V inverter is the only thing I know which can match an array voltage with no modification. I do run a washing machine off four gid tie panels and no battery. That does take more technical skill. Our town recycling is filled with battery packs that were supposed to save us in an emergency. They died from neglect and were likely never used once. This is a cheap no maintenance system that will provide the basics in an emergency. It can charge a tractor in a remote shed and keep power tools charged. You could also heat water with 60V and have the system pay for itself. The beauty of this design is there is no excess. It provides just what is needed in an emergency with no maintenance at very low cost. This would be a great asset on a remote hiking trail.