Which to buy first - Generator or Batteries or Tracker

dexter12353 · November 2017

For reference, see my last thread for my setup.
http://forum.solar-electric.com/discussion/352776/off-the-grid-video#latest

Setup:

16 group 8D deep cycle batteries - 255AH@12v - Bank is wired for 1020AH@48v
Inverter: Sigineer power 12KW Pure Sine Wave Inverter
CC's: Dual outback FM80's

Solar:
- 16/ea 210 watt solar panels, Flat, laid on top of a shipping container, connected to one of the outbacks
- 6/ea 210 watt panels, on tracking rack, plus 3 250 watt panels on second tracking rack, and 3 in a fixed orientation pointing south. all on one outback (I hear the screaming already!) NOTE: These are currently strapped in a flat orientation as a strong wind can destroy the actuator motors (Only rated for 330 lb - CheapO Amazon actuators)

Generators: 2/ea Honda EU2000I and 1/ea EU3000I, all paralelled together. This feeds a 120x240v step up transformer going to the battery charger. Note: All generators are pushed to their limits for power in order to run just the battery charger. Turning on any other appliances will send the generators to overload and transfer the draw to the inverter causing huge stress on the inverter. (I've blown up one inverter this way already).

Question:
In summer time we are pretty much set for power, both generation and storage.

Here is now winter time and we are not doing so well on our generation side of the setup. The sun is just not present.

Given a budget that grows with how long I wait to actually do something

A. Upgrade the batteries so I don't have to come home and put gas in the honda's so that in four hours when the bank is full I have to wake up and go shut the generator off - I can then let the system run until the morning and have someone else start a generator every-other day? Would be 16 batteries at $165/ea - About $2750 when all is said and done and installed. Would take about four weeks to have in-place.

B. Put the 16 solar panels that are currently sitting flat on a tracking rack with strong enough motors to be strong enough to hold up to the wind caused by winter months to better increase power production. Note, this wont have too much of a gain on the cloudiest of days. This would cost about $1400 and would be approx 5 weeks to have in place.

C. Buy a generator that has 2 wire start, if the solar does not do good enough then the Outback CC's go and fire up that generator and shut it down when the power situation is back where it should be. Cost: Approx $6500 (Note: 14KW minimum, must be diesel, would prefer new vs used) Would take about 12-14 weeks to have in place.

I need to pick one, that way I can set it as my goal financially...but keep in mind that buying one thing takes the cash from the next....

In my situation, what would you do?

Thanks in advance for all of your feedback. It's a tough call.

mcgivor · November 2017

Being that the battery is sufficient in summer, adding to the capacity would mean the PV would be at a greater deficit during winter, which in turn would require more generator run time, or a larger generator. Flat panels would under produce unless they are at the equator, adding tracking would require spacing to prevent shadows being cast from neighboring panels, not to mention added complexity, susceptibility to wind and maintenance. So of the 3 choices the generator looks the best, although in summer months it may be superfluous unless used for other loads.

What would I do? If the panels are indeed flat mounted and at a high latitude, I would tilt them using a frame built with unistrut, perhaps adjustable for seasonal changes to get maximum performance, without complexity, then consider a larger generator,if needed. Unless of course you are at the equator.

mike95490 · November 2017

Do the generators ONLY charge batteries, or do they power any loads directly ?

What is your 240V battery charger ?
What is the power factor (PF) rating of it, poor power factor can cause lots of overload power issues.

Look into the extended run fuel caps for the honda inverter gens. Cheap improvement. Can you charge batteries, and as they fill and charger load reduces, take one genest off line ? Can you charge from genset/charger and run loads off the inverter, while you charge ?

clockmanfran · November 2017

I have 14kW of PV, 5kW is on three trackers, 3off 3.7m (12footers), HP design wind turbines, but for my power use I use the worst case scenario ie, 10% to 20% output of my PV in ambient light conditions, e.g. its a murky winters day.

So that's a constant 1.3kw every murky day. But still not enough.

30kW of PV will get me what I want.

We do a book here, How to make a 2kW solar PV Tracker, but that's taken 4 years of testing and modifications to keep it simple, robust, and importantly cost effective. And yes they have survived a real hurricane wind conditions.

Strange really, as Now I tell folk to do static arrays, ground mount or roof mount, as PV is getting cheap.

PV is far more cost effective than domestic wind turbines, and PV tracker machines. A added bonus with static mounted PV is it requires very little working maintenance.

However, if you can not do masses of good PV, then Sorry looks like you need to get a good Generator.

dexter12353 · November 2017

> @mike95490 said:
> Do the generators ONLY charge batteries, or do they power any loads directly ?
>
> What is your 240V battery charger ?
> What is the power factor (PF) rating of it, poor power factor can cause lots of overload power issues.
>
> Look into the extended run fuel caps for the honda inverter gens. Cheap improvement. Can you charge batteries, and as they fill and charger load reduces, take one genest off line ? Can you charge from genset/charger and run loads off the inverter, while you charge ?

Generators take over the loads and take care of battery charging. The 240 volt battery charger output 120 amps at 48 volts. The watt draw is right at the capacity of the generators, but I don't know the exact power factor. I have tried shutting down generators as the draw of the battery charger reduces however it leaves less margin for loads. The inverter has a built-in transfer switch so it can either be only inverting or only charging it won't do both unfortunately.

I'm not at the equator. I'm in the middle of California.

Estragon · November 2017

I would definitely go the diesel generator route. The hondas are great for occasional use, but aren't meant to constantly run at their limit.

As Mcgivor said, adding more battery to your (already not ideal) bank is just adding to the deficit charging problem. Tilt would help a bit, as would more pv, but if the sun just isn't there, probably not enough to solve the problem.

Properly used and maintained, a good 1800rpm diesel should last decades, and is almost certainly the best and cheapest long term solution.

Dave Angelini · November 2017

I think the first item on your list is your biggest problem. I have been using some form of tracking for over 25 years now. I would like to tell you that it will help you. Until you have a battery system that meets your energy usage capacity, you are just going to have problems.

You probably need a a battery made of (24) 2V 1,100 AH cells and that is around $8K. Your other problem is the inverter does not seem to be giving you the data that an Outback or Schneider offgrid unit would.

Wait until you can do this right and just do the best you can. Good Luck!

softdown · November 2017

My vote is the diesel genset. Though I wish people would tell their location first. Diesels do not like weather much below 0F. If that is common, propane looks attractive.

With ethanol in our gasoline, small engines become disasters waiting to happen. Wait, change that....With ethanol in our gasoline, gas engines become disasters waiting to happen

Estragon · November 2017

Even propane (actually LPG- liquid petroleum gas) can be a problem in really cold temps too. Pressure can get too low for some uses, and if the blend has a relatively high amount of butane in the blend, may not vapourize much at all.

I put anti-gelling additive in the diesel for winter, which seems to work in the ~ -25-35°C weather we get. At those temps, I do like to warm the genny (but not the fuel) up a bit with a space heater, mainly so lube oil can get where it needs to be for the first couple of minutes.

Ethanol in gas... bah. Corn should be for flakes, not gas!

softdown · November 2017

I have not heard of these problems with propane before. It got down to -25F in the Black Hills and the propane never faltered once. Everyone used propane around here and I have yet to hear of a problem in a region that can see -30F.

My suspicion is that it may be unusual for propane to malfunction due to cold weather. Unless, of course, it gets down below -40F or so. I don't think we have any active Alaskan posters. Used to....

Humans were not meant to live comfortably when temperatures commonly fall below ~ -25F....or so. Even the ancient Vikings gave up on Greenland after awhile.

Estragon · November 2017

IIRC, (pure) propane stops vaporizing around -45. At -25, it just has lower pressure. It works okay on my stove, but not sure about on-demand water heater yet.

Last summer I took a tank in to be filled that ran out last winter. Turns out it was still ~1/3 full.

Which to buy first - Generator or Batteries or Tracker

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