Monday, February 27, 2023

Solar options for outages

 Recently I finalized my DIY solar install on my home.  I purchased a kit around 2021 and jumping through all of the needed hoops, and the added complication of having a generator bypass on my electric panel meant I had to blindly bump my way through the install.  My system is a typical grid tied setup.  However since I purchased the equipment newer setups that enable whole home backup have come about.  Some are off grid systems that won't spin your meter backwards, but will enable you to have more control over your power.  Others are fully hybrid systems that can spin your meter backwards even at night and keep your house powered in an emergency.  

We recently had a power outage here thanks to ice storms.  Many people have been asking if they should purchase a generator.  My response is while you can purchase a generator they are much like snow throwers.  You have to buy them when you don't need them, you have to maintain them through the year to make sure they start when you do need them, and finally even if you do they abide by "Murphy's law" and typically won't run when you do need them.  Portable generators and Whole home generators need maintenance to make sure they work when you need them to.  Whole home generators typically come with maintenance contracts where someone does this for you through the year that usually cost $300 plus the cost of parts needed.  Portable units are yours to deal with or take into a small engine shop.

There is another option however.  Solar backup is now something that you can have installed relatively at parity with the cost of a generator.  Also, these systems can be used in ways that a generator simply cannot.  

For each of the below categories I'm going to design a system that can be used for backup power.  Each of these can be carried forward and grown with time.    The idea being you can purchase some parts as you start out and grow with time.  These are off grid systems so they will not sell your power back to the utility company, but they can lower your bills as they can charge overnight when power is cheaper and use that power during the day when it's more expensive.  Or even better they can also use solar power further reducing your energy usage.

There is one exception I'm saving for the end for people who own a home and want a fully installed solar system.


Something rarely considered when it comes to backup power is what someone who lives in an apartment is supposed to do.  Generators must be used outdoors and minimally 30 feet away from any doors or windows.  In an apartment this can be difficult or even impossible to do.  Generators cannot be used indoors as the carbon monoxide they produce is lethal.  This has lead to many deaths every year in emergency situations.  It's also the reason why all new generators sold have carbon monoxide emergency shut-offs to kill the generator if levels rise.

Battery based backup solutions, sometimes marketed as "Gasless Generators", do not have this problem and can be safely used indoors.  They produce no noise other than a fan, and can either charge over night or via solar panel inputs.  Unfortunately as most apartments have no "transfer switch" built into the unit you'll have to unplug things like a refrigerator and plug them into the battery pack, but anything that can be plugged in can be used.  Computers, Refrigerators, even portable heaters.  Hopefully with code changes battery integration will become mandatory for all apartments so that renters can bring their own units and ensure their power costs remain low or $0, and provide them with backup power in emergencies.

Here's the setup I'd recommend for an apartment:

An Ecoflow Delta Pro

This unit acts as the central hub for power.  It can be paired with other ecoflow equipment in the future.  Both additional batteries expanding it to a whopping 25kw.  Each battery is fully portable so you can just extend the handle and carry it with you.  In an emergency if you cannot generate solar (say it's too dark or you just can't get panels outside) you can wheel this out to any Level 2 EV charge station and top this up from empty quickly.  Even a friends garage with a 6.6kw charger could get this fully charged in less than an hour and you are back in business.  With solar panels however you may not even need to take this out to charge.  For an apartment I'd recommend either portable panels that fold up such as these:

Or for a more permeant install that you set up in a ground / patio mount and secure down I'd recommend 1 pack of these:

The trick with this being the Ecoflow Delta Pro can accept 150V solar input at 15Amp.  This means one string in series.  You can buy any solar panels, even used ones.  Just check the specs to what they can output at most voltage, and figure out how many panels will fit in that 150V limit.  If you have a panel rated for 35v max, you can easily use 4 in series.

As mentioned before you can pack up the unit, cabling, and even your solar panels and take them with you when you move.  Portable panels can be used constantly if you want to make a mount, and taken with you easily for camping or to use at a friend's place if they need backup power.

Small Homes\Town Homes

Growing the solar install from before lets look at a small home or town home.  With these types of houses you typically have the ability to make changes such as adding a sub panel for backup power.  Keeping to the Ecoflow Ecosystem Here's what I'd recommend depending on if your house is gas or electric.  Meaning are the major appliances such as the stove, oven, drier, and hot water tank gas powered or electric?

This design gives you 10 circuits of power.  It doesn't matter if it's a 120v or 240v appliance.  So you can run your furnace, hot water tank, fridge, stove, lights or internet and tv.  I'd avoid the microwave as those put a huge stress on backup power.

In all cases I'm going to recommend a Smart Home integration panel from Ecoflow.  This makes the hookup of your batteries simple and gives you control over how you use your power.  If your batteries don't charge fully in the day you can recharge overnight with lower energy rates from your provider.

Here's what I'd recommend.

  • One Smart Home integration Panel:  Put all your essential loads, up to 10, on this panel.  You'll need an electrican to install this.
  • Minimally 1, but more preferably two of the Ecoflow Delta Pro units.
  • Each Ecoflow delta pro can support 150v Solar each.  So for each Delta Pro you buy also get one set of solar panels.
  • Finally if you want more power for each Delta Pro you have you can add expansion batteries.  Keep the system balanced.  For each Delta pro buy one of these.

Mid size to Large Homes

Now for a large home you have options.  You can very easily use the Ecoflow design from the small home section if you're fine with 10 circuits of power.  However if you're looking at a whole home generator and are already fine with a $20k price tag let me recommend the following:

Call signature solar to get your full setup designed.  Treat this kit as a starting point not a fully realized system.  This price is not all inclusive.  When you add in panel racking, nec2017 compliance devices, copper wire, and electrical install to your panel (assuming you DIY the panel install, otherwise add more for the panel install) you can easily be looking at $24k before the tax rebate.  HOWEVER this system can be adjusted to run your entire house.  If your load is too big for one inverter more can be added in parallel.

The benefit here over the Ecoflow system is this is a hybrid system.  Not only will it provide backup power it will also sell your excess power back to the utility company.  So this system can pay for itself faster than off grid systems even with it's higher up front cost.  With the average monthly power bill being $122 that's 16 years to pay off the system.  However large homes frequently have higher power bills especially if the house is mostly electric appliances and if Air Conditioning is used.  In my case my summer bill can top $350 and winter bills are closer to $140.  My yearly energy expense was $2,940.  Once calculated my payback on this system should be 8 years.  However there are further ways to lower the payback period faster.  If you have a heat pump instead of an Air conditioner you can reduce your natural gas usage in the winter.  Imagine $0 heat bills.  As my heat bill this winter has been $400 per month over the last 4 months that's $1600 per year.  Or if you get a electric car to replace your vehicle you can eliminate your fuel costs.  In my case that was another $2,500 per year.

As my system was a grid tied model, once I finished my upgrades my payback period was 4 years.  Raising natural gas, energy, and gasoline prices have further reduced this.  I'm staring at a 3 year payback period.  My electric, gas, and natural gas usage is reduced to near $0 per month.

As these monthly bill prices continue to rise and as solar and battery prices drop this payback period will only get shorter.  At this point a solar system of any type should be considered a retirement investment instead of a green project.  At the rate these costs go up, it's a better investment than most you can achieve.


As I stated the solar industry is moving incredibly quickly.  Multiple products have come out that changed or modified my suggestions.  Many new portable solar + storage solutions for apartments and homes have come out including a new ecoflow solution specifically for apartments.  On the other end Signature Solar has introduced a new larger hybrid inverter for home backup power.  This is just one possible kit.

There are now kits for most budgets.  My suggestion, skip a generator.  If you find you're in the market for backup power right now start looking at Solar instead.  A solution that provides backup power via solar is not only at price parity with a stand by generator right now it's much cheaper after the 30% tax rebate going on.  In addition a generator will never pay you back.  It's a constant expense every year for oil changes, starter batteries, and air filters.  A solar system has none of that and will start paying you back from the minute you turn it on.  Even if you don't get a $0 power bill you'll wind up paying much less than you were.  Also start with an inverter with room to grow or additional inputs.  Mine was sized to my house and array, and now that I'm thinking of adding more panels I'm stuck buying a new inverter and selling the other.  Again it was the best solution just 3 years ago.  Now with the EG4 inverters coming out much better options are out there where you start small and grow over time.

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