Solar power is such a hot topic these days. Here in Florida, where most homes have some sort of backup power device, usually in the form of a gas generator, I wanted to examine the Portable solar generator and see whether it is a viable option for emergency or off-grid power. This may be a viable option for you as long as you have light to moderate backup power requirements.
How Much Power Does a Solar Generator Deliver?
Solar power generation can be a tricky and complicated subject simply due to all the variables on the power input side, storage, conversion and consumption or load on the system. A portable, suitcase sized solar setup contains the necessary core components which are:
- solar panel
- charge controller (some include 5V USB output direct from the controller)
- inverter for powering AC electronics
This system can be highly portable, perhaps using a lithium ion battery for power storage and therefore minimum weight and bulk, and deliver from about 100 to 2000 watts of power. Such a system may in fact be the best possible use of solar today as this system would be likely called upon to power a couple of lights, charge a phone or laptop, and other light-use appliances. The Acopower 120W solar panel with charge controller is a good choice here.
The toughest part, in my opinion, about solar power generation on a larger scale, say for home or cabin power, really comes down to how much power can you store and how fast can you replace the power you’re pulling from that storage. Simple concepts but if you choose certain components poorly, the final product could turn out to be an expensive pile of semi-useless junk.
Deep cycle batteries are at the heart of the system and are as good a place to start when considering solar power. A basic concept is to consider what happens when your 100 amp hour battery is depleted to half capacity – which is the maximum depletion you should allow. If your solar panel and controller output 1 amp per hour of power in full sun, you would need 50 hours to recharge. Real world conditions mean that your charge time is probably close to 100 hours.
Battery ratings are misleading as well. A 100 amp hour battery at 12 volts should provide 1200 watt hours of power, right? Ah…no it won’t. First off, you never want to discharge it past 50 percent, so it’s basically a 50 amp/hr battery. With system inefficiencies, DC to AC conversion and other factors, you end up with something more like 500 watt hours of power from a single, fully charged, 12-volt deep cycle battery.
So, a really crappy portable 500-watt hair dryer would cease working after about an hour with a single deep cycle battery powering it!
Now, you’ve got to recharge that battery, (presumably to further dry your still damp hair), and you need to replace 50 amp/hrs of power. You will at least want a system that provides 10 or so amps…. which would still take 5-8 hours to fully recharge.
There are many other factors in play here such as the fact that the battery will provide more resistance as it nears full charge, solar panels are never 100% efficient, partial blockage of the sun on the panel will affect it’s output, controller overhead, and on and on.
Here again, the devil is in the details as your panel ‘array’ needs will vary with such things as your physical latitude, climate, foliage etc. But regardless, we are talking about several panels wired together, whether in series or parallel, providing 3 to 4,000 watts minimum, to a controller and bank of deep cycle batteries. Pretty serious stuff.
Renogy also sells a 100 Watt portable solar generator in a suitcase setup. This one using a monocrystalline panel set and comes with their charge controller. This is a also a great portable power setup.
These are just some of the basics and they suggest that to scale up the power sufficient for home or cabin use, you’re going to need lots of panels and batteries.
How Reliable is Solar Power?
The reliability you experience with your system will likely depend on both the quality of the individual components used, and whether you are using the system in the capacity for which it was designed. Other words, if you continuously push the system to it’s failure point, by totally depleting the batteries and/or never achieving a full recharge, your system will have a much shorter life.
Other factors are things you can’t much control such as weather, (windstorms and falling tree limbs are my biggest concern), cloud cover etc. You can control power draw to some degree. You certainly control such things as battery maintenance, wiring and connector checks and the like.
All things considered, solar is a very reliable power source and potentially much easier to live with than you may be thinking at the moment.
What is the Cost of Solar Power Equipment?
The cost of solar panels have fallen dramatically in the last 10 years, largely due to China’s participation in the market. This is controversial as the cheap Chinese panels often came with problems, however I have seen more recent examples of Chinese panels, even flexible ones that were surprisingly good…. much improved over the stuff in the past. I would always prefer a domestic panel, but I also believe that choice is good and it keeps the big players in check.
Large solar systems are sold largely based on the concept of ‘return on investment’, which I’m sure you’ve read about and are even perhaps considering. I know people who have spent from about $7,000 to high $20,000 on their system. When you compare that to the cost of a new Kia, it isn’t bad, but it is a substantial commitment, none-the-less.
Personally, my belief here is that a whole house, back-fed system that powers everything from well to central air conditioner is a bit more advanced and expensive than it’s worth – to my tastes – at this point in history.
This may upset some of you, I know….. but I think the cost of the equipment needs to evolve downward another 30 to 50 percent and the biggie – batteries have got to evolve more for home use. We have ROV’s driving around Mars but we’re using battery technology from the late 1800’s? Makes no sense to me.
My idea of the perfect home solar setup is a ‘Grid-tied’ inverter setup, something I plan to devote time and space to in an upcoming article.
Is Solar Power a DIY Job or Do I Need a Pro?
For me, it’s DIY all the way. I would suggest that if you need a pro, be very careful and perhaps you just want someone to mount the panels or run the wire. My best advice would be to learn as much about the hardware, it’s function, interaction, capability, etc, and the best possible way to do this is to build yourself a small system and in so doing, acquire the skills you’ll need to select and implement a larger system down the road. With a solar power system, you are taking the job of providing your home’s power onto your shoulders. No more flipping the light switch and just assuming that the electrons are just waiting to burst forth, it’s up to you and only you to make those pixies dance, and to keep them coming.
My opinion here is that you take things slowly and unless you have a background where you understand the basic concepts of solar equipment, that learning about it is way better than trusting a salesman who is trying to fill a sales quota by selling systems. Even if you ignore that advice and buy a solar system you don’t fully understand, when something breaks, which will happen, you will want to have arranged a friend or family member who does understand it all to be readily available.
For portable power needs whether at the campsite, for the RV or even as a temporary system at home to use during storm season, a portable solar generator is pretty awesome. The biggest adjustment is dealing with power draw, but this is a system that is being utilized outside the normal routine, so it is much different mentally than shifting your life to a permanent solar power system.
Yes, for modest emergency or portable power, the time has definitely come to invest in a portable solar generator. For whole home needs I would move on and look at the concept of the grid-tied inverter system.